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Hamilton C shell(tm) User Guide and Reference Manual Release 2.1 April, 1993 Hamilton Laboratories, 13 Old Farm Road, Wayland, MA 01778-3117 Phone 508-358-5715 + FAX 508-358-1113 MCI Mail 389-0321 + Internet 3890321@mcimail.com BIX hamilton + CompuServe 70034,2025 + Telex 6503890321 Copyright (c) 1988 - 1993 by Hamilton Laboratories. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission from Hamilton Laboratories. Printed in the United States of America. AT, PS/2 and OS/2 are registered trademarks of International Business Machines Corporation. Windows NT is a trademark of Microsoft Corporation. UNIX is a registered trademark of UNIX System Laboratories. Hamilton C shell is a trademark of Hamilton Laboratories. Table of Contents Preface .................................. v License Agreement....................... vii Introduction ............................. 1 Installation Guide ....................... 3 Installation on OS/2 3 Installation on Windows NT 15 Common Problems ......................... 18 Product Support ......................... 29 User Guide .............................. 32 The Utilities 38 I/O Redirection and Piping 55 The History Mechanism 66 Variables 70 Wildcarding 79 Editing 88 Quoting 93 Expressions 97 Aliases 106 Programming Constructs 109 Scheduling 131 Order of Evaluation 138 Customizing the Shell 141 Summary 153 Examples ............................... 155 Factor.csh 155 Whereis.csh 156 Samples Directory 157 Compatibility Guide .................... 162 Language Reference ..................... 172 Basic Statements 172 Condition Testing 172 Iteration 175 Procedures 175 Aliases 176 Variable and Expression Manipulation 176 Local Variables 178 Function Keys 179 iii Miscellaneous Statements 181 Statement Relationships 183 I/O Redirection 183 Expression Operators 185 File System Tests 187 Special Devices 188 Wildcarding and Pattern Matching 190 Filename Completion 192 Command Line Editing 193 History Recall 196 Command Completion 196 Quoting 198 Escape Sequences 198 Variable Substitution 200 Substitution Modifiers 201 Pathname Editing 203 Predefined Variables .................... 205 Environmental Variables 205 Process-Wide Variables 210 Per-Thread Variables 212 Variables, Sorted by Name 218 Built-in Procedures ..................... 230 Utilities ............................... 235 Popular Aliases ......................... 242 Help Information ........................ 248 Help for the shell 248 Help for the utilities 250 iv Preface Thank you for purchasing and using Hamilton C shell. Our goal and guarantee is your satisfaction. Hamilton C shell is an advanced command processing language for OS/2 and Windows NT. It's a professionally- oriented language for manipulating files, processes and threads and connections between these objects. As a language, it offers what we think of as the human characteristics of language: a useful vocabulary and grammar, a limitless freedom of expression and the ability to describe and relate events in time. Most important, it projects your influence into the future by allowing you to easily describe you want done even if what you want is quite complex and dependent on future events. Hamilton C shell is a full implementation of the C shell language popular on engineering workstations. It was created specifically for OS/2 protected mode and meticulously ported to Windows NT. Not one of the more than 95,000 lines of code in the current release was created on or ported from anything but OS/2 or NT. This product complies with accepted standards for the language and with the conventions of OS/2 and NT. Users with previous experience with the standard OS/2, NT or DOS command processors or the original Unix C shell should find enough reasonably familiar language constructs and features to make the product immediately productive. Douglas A. Hamilton Wayland, Massachusetts December 9, 1988 (Last revised April 22, 1993) v vi IMPORTANT -- READ CAREFULLY BEFORE OPENING. By opening this sealed package, you indicate your acceptance of the following Hamilton Laboratories License Agreement. Hamilton Laboratories License Agreement This is a legal agreement between you, the end user, and Hamilton Laboratories. By opening this sealed package, you are agreeing to be bound by the terms of this agreement. If you do not agree to the terms of this agreement, promptly return the unopened package and any accompanying items for a full refund. HAMILTON LABORATORIES SOFTWARE LICENSE 1. GRANT OF LICENSE. Hamilton Laboratories grants to you the right to use one copy of the enclosed Hamilton Laboratories software program (the ``SOFTWARE'') on a single terminal connected to a single computer (i.e., with a single CPU). You may not network the SOFTWARE or otherwise use it on more than one computer or computer terminal at the same time. 2. COPYRIGHT. The SOFTWARE is owned by Hamilton Laboratories or its suppliers and is protected by United States copyright laws and international treaty provisions. Therefore, you must treat the SOFTWARE like any other copyrighted material (e.g., a book or musical recording) except that you may either (a) make a reasonable number of copies of the SOFTWARE solely for backup purposes or (b) transfer the SOFTWARE to a single hard disk provided the original and any other copies are kept solely for backup or archival purposes. You may not copy the written materials accompanying the software. 3. OTHER RESTRICTIONS. You may not rent or lease the SOFTWARE, but you may transfer the SOFTWARE and accompanying written materials on a permanent basis provided you retain no copies and the recipient agrees to the terms of this Agreement. You may not reverse engineer, decompile or disassemble the SOFTWARE. If SOFTWARE is an update, any transfer must include the update and all prior versions. 4. DUAL MEDIA SOFTWARE. If this SOFTWARE package contains both 3 1/2'' and 5 1/4'' disks, you may use only the disks appropriate for your single-user computer. You may not use the other disks on another computer or loan, rent, lease, or transfer them to another user except as part of the permanent transfer (as provided above) of all SOFTWARE and written materials. LIMITED WARRANTY LIMITED WARRANTY. Hamilton Laboratories warrants that the SOFTWARE will perform substantially in accordance with the accompanying written materials for a period of 90 days from the date of purchase. Some states do not allow limitations on the duration of an implied warranty, so the above may not apply to you. CUSTOMER REMEDIES. Hamilton Laboratories' entire liability and your exclusive remedy shall be, at Hamilton Laboratories' option, either (a) return of the price paid or (b) repair or replacement of the SOFTWARE that does not meet this Limited Warranty and which is returned to Hamilton Laboratories with a copy of your receipt. During the first 90 days from the date of purchase, if you determine that the SOFTWARE is unsatisfactory in any way, you may return it with proof of purchase and a written description of why the SOFTWARE was unsatisfactory for a full refund. NO OTHER WARRANTIES. Hamilton Laboratories disclaims all other warranties, either express or implied, including, but not limited to implied warranties of merchantability and fitness for a particular purpose, with respect to the SOFTWARE and accompanying written materials. This limited warranty gives you specific legal rights. You may have others, which vary from state to state. NO LIABILITY FOR CONSEQUENTIAL DAMAGES. In no event shall Hamilton Laboratories or its suppliers be liable for any damages whatsoever (including, without limitation, damages for loss of business profits, business interruption, loss of business information, or other pecuniary loss) arising out of the use of or inability to use this Hamilton Laboratories product, even if Hamilton Laboratories has been advised of the possibility of such damages. Because some states do not allow the exclusion or limitation of liability for consequential or incidental damages, the above limitation may not apply to you. This Agreement is governed by the laws of the State of Massachusetts. Should you have any questions concerning this Agreement, or if you wish to contact Hamilton Laboratories for any reason, please write: Hamilton Laboratories Customer Service, 13 Old Farm Road, Wayland, MA 01778-3117. Introduction Hamilton C shell(tm) Introduction Hamilton C shell is a language for interactively using OS/2 and Windows NT. Compared to the standard OS/2 and NT command processors, it provides a vocabulary and grammar that allows much more complex activities to be described. Some of its major innovations include + Command line editing of enormous statements with arrow keys and filename and command completion. + User-definable function keys. + Fully recursive grammar. Statements can be arbitrarily nested or piped without concern for statement length or other arbitrary restrictions. + Procedures and aliases. The vocabulary of the language is meant to be extensible by the user. + Variables, arrays and expressions. Integer and floating point arithmetic, pattern matching facilities and various file system tests and editing operators provide an expressive grammar. + Threads and processes. Child threads and processes can be spawned to run commands asynchronously or in the background. + Command substitution. The output of one command can be stuffed back on the command line as arguments to another. + History. Past commands can be recalled and edited. + Advanced filename wildcarding. This product complies fully with industry-accepted definitions for the C shell language. The user is not asked to learn yet another new proprietary language not available anywhere else. Instead, a tested, proven framework has been adapted with modern compiler technology for OS/2 and NT: Page 1 Introduction 1. A modern top-down parser is used for better language recognition and performance. 2. It's easier to use. The syntax and grammar has been made flexible and more consistent with other modern high level language conventions. 3. It knows about OS/2 AND NT: HPFS, long filenames, environmental variables, networks, international character sets, how to start PM applications and (under OS/2 2.0) about 32-bit and Virtual DOS machine (VDM) applications. 4. Threads are used extensively to achieve performance and functionality not possible in UNIX. 5. Feedback to the user, especially when reporting errors has been improved. Who is it Designed For? Most users of Hamilton C shell are relatively technically oriented computer users. Often, they're software developers. They have a business need for an OS/2 or an NT system. Peering over their shoulders, they typically have lots of windows open on the screen. Many of the windows are running copies of this shell. Some copies are transient, created to display with little snippets of information needed on the spur of the moment. Other copies of the shell would be used for more long-running projects: for example, getting a make working for a major application. A shell window is like any other application window but with a different paradigm. Instead of data, rows and columns of numbers or lines of text, the object being manipulated is the machine itself. A good shell tackles a different problem than icons and windows. Instead of the point-and-shoot immediacy of ``do this single thing now,'' a shell offers language and the ability to describe more customized or repetitive actions, e.g., identify a suitable set of files, perform some action against them and filter the results in some interesting way. Page 2 Installation Installation Guide This section outlines how to install the Hamilton C shell on your system. If you are installing the OS/2 version, follow the instructions beginning on this page. To install the Windows NT version of Hamilton C shell, please turn to page 15. If you encounter problems, consult the ``Common Problems'' section on page 18 or call us for technical support as described on page 21. Installation on OS/2 The first few steps, copying files from diskette to your hard disk and modifying your config.sys, are the same on all releases of OS/2. The remaining steps -- those associated with actually installing Hamilton C shell on your OS/2 desktop -- depend on which release of OS/2 you're running. We suggest a ``vanilla'' installation initially, but later you may want to customize it to your own tastes. For help with that, read the chapter on ``Customizing the Shell,'' beginnning on page 141. Once you've gained familiarity with both OS/2 and with the C shell, you may want to set up the C shell as the default command processor for OS/2, completely replacing cmd.exe as described on page 10. The advantage to be gained (except under the 6.167 Beta and LA builds of 2.0) is that the C shell will then be able to change its own title bar and icon when you run an external command. System Requirements Installation requires a 286-, 386- or 486-based AT(R) or PS/2(R) or compatible, running OS/2(R) 1.1 (Presentation Manager) or Microsoft SDK 1.06 or later. To run the 32- bit version (expected to be available in January, 1993), you'll need to be running OS/2 2.0 or later. Roughly 1 MB of disk space is used. Hamilton C shell and the utilities supplied with it fully support HPFS and long filenames when running under OS/2 1.2 or later. They will work properly in a Presentation Manager text window or full-screen and with networks such Page 3 Installation as LAN Manager or IBM LAN Server. If you're using OS/2 2.0, it knows how to run 32-bit applications and start up Multiple Virtual Dos machines. The product is not copy protected. Basic Installation, Part I (All releases of OS/2) 1. Copy the executables in the bin directory into any desired directory on your search PATH, so long as it appears ahead of the directory containing the standard IBM/Microsoft more.com. (We supply a dramatically improved more.exe, which should take precedence.) If you're creating a new directory, remember to add it to your search PATH in config.sys and in the login.csh file you create next. 2. Edit config.sys, adding statements to define whatever directory you choose to designate as your HOME directory and to ensure you're configured for a sufficient number of threads. The significance of a home directory is principally that it will be convenient to specify pathnames relative to that directory. The default number of threads is too small if you expect to have lots of windows open. Also, be sure your PATH explicitly lists ``.'', the current directory. You may also want to include definitions for TABS and COLORS. more.exe and some of the other utilities look for TABS to see if you want them to display text with tabs expanded out to something other than the default of every 8 characters. By default, the C shell displays white characters on a black background. The COLORS variable lets you choose something different from this set: black, red, green, yellow, blue, magenta (or blue red), cyan (or blue green) and white. Foreground colors may also be bright, dim, blink or reverse. The keyword ``on'' introduces background colors. (Blink only causes true blinking full-screen; in a text window, it just makes the background brighter. Also, yellow is a true yellow only if it's bright. These are OS/2 limitations not related to the C shell.) For more information on setting screen colors, please refer to the customization chapter or to the colors.csh file in the samples directory. Here's an example of what you might add to config.sys: Page 4 Installation THREADS=255 SET HOME=D:\DOUG SET TABS=3 SET COLORS=WHITE ON BLUE (Please be sure your config.sys file contains only upper-case alphabetics, no lower-case, if you're using OS/2 1.1. Lower-case alphabetics were known to cause random OS/2 system failures in that release of OS/2. This was a known bug in the OS/2 kernel and was not application dependent.) 3. Copy the login.csh and startup.csh files into ``home'' directory. Unless you're convinced that you've set all your environmental variables in your config.sys (and that your PATH explicitly lists ``.'', the current directory), use the dumpenv utility to paste a series of setenv statements into the login.csh file to recreate the environment you've been using with cmd.exe: dumpenv >>login.csh (To see what dumpenv does, look at the source code in the samples directory or simply run dumpenv without redirecting the output.) The login.csh and startup.csh files can be edited with any ascii editor to customize the shell to your needs. The login.csh file has a lot of comments in it which can take the shell a second or more to read; you'll almost certainly want to delete some of them once you've read them so the shell will start up faster. Also, any setenv statements that just duplicate what's in your config.sys can be discarded. The remaining steps depend on which release of OS/2 you're running. Basic Installation, Part II (OS/2 1.1) 4. Add csh.exe with the title ``Hamilton C shell'' to the ``Start Programs'' menu. To do this, pull-down ``Program'' and select ``Add...'' from the menu bar. Fill in: Program title.... Hamilton C shell Path and file name ....as Page 5 Installation appropriate....\csh.exe Parameters.... -L The ``-L'' part tells csh.exe when it starts up that it's a ``login'' shell, which means it should look for a login.csh file. (Refer to page 248 for additional information on other options.) 5. You will likely want to create a second entry for running full-screen. It's more convenient if you're mostly working with applications that only run full- screen or if you want faster text display, especially scrolling. To do that, from the ``Start Programs'' menu, pull-down ``Program'' and select ``Copy...'' from the menu bar. In the Copy Programs popup, fill in the following and push the ``Copy'' button: Change Title to: Hamilton C shell -- Full Screen Back in the ``Start Programs'' window, select the new full screen title, pull-down ``Program'' and select ``Change...''. In the Change Program Information popup, push the ``Change'' button. This brings up the How to Run the Program popup; select ``Run the program full-screen'' and ``Enter''. 6. All the material in the samples directory is provided for its tutorial value; you may or may not wish to copy it onto your hard disk. 7. Reboot your system before starting Hamilton C shell for the first time. This causes the new statements in config.sys to take effect. Page 6 Installation Basic Installation, Part II (OS/2 1.2 or 1.3) 4. Add csh.exe with the title ``Hamilton C shell'' to the ``Group - Main'' menu. To do this, pull-down ``Program'' and select ``New...'' from the menu bar. Fill in: Program title: Hamilton C shell Path and file name: ....as appropriate....\csh.exe Parameters: -L The ``-L'' part tells csh.exe when it starts up that it's a ``login'' shell, which means it should look for a login.csh file. (Refer to page 248 for additional information on other options.) 5. You will likely want to create a second entry for running full-screen. It's more convenient if you're mostly working with applications that only run full- screen or if you want faster text display, especially scrolling. To do that, from the ``Group - Main'' menu, pull-down ``Program'' and select ``Copy...'' from the menu bar. In the Copy Programs popup, fill in the following and push the ``Copy'' button: Change Title to: Hamilton C shell -- Full Screen Back in the ``Group - Main'' window, select the new full screen title, pull-down ``Program'' and select ``Properties...'' . In the Properties popup, push the down arrow next to the ``Program Type:'' box and select ``OS/2 Full Screen'' on the list that will appear and then push the ``Change'' button. 6. All the material in the samples directory is provided for its tutorial value; you may or may not wish to copy it onto your hard disk. 7. Reboot your system before starting Hamilton C shell for the first time. This causes the new statements in config.sys to take effect. Page 7 Installation Basic Installation, Part II (OS/2 2.0) 4. Open the Templates folder and drag a program object to the desktop (or another folder) by pressing and holding the right mouse button as you drag. On the Program page of the ``Program - Settings'' window that will appear, fill in: Path and file name: ....as appropriate....\csh.exe Parameters: -L The ``-L'' part tells csh.exe when it starts up that it's a ``login'' shell, which means it should look for a login.csh file. (Refer to page 248 for additional information on other options.) 5. On the Window page of the Settings, you will probably want to set Minimized button behavior: Minimize window to desktop Object open behavior: Create new window Doing this will let you conveniently open up lots of copies of the C shell as needed. 6. On the General page of the Settings, set Title: Hamilton C shell Close the Settings by pressing Alt-F4. 7. You will likely want to create a second entry for running full-screen. It's more convenient if you're mostly working with applications that only run full- screen or if you want faster text display, especially scrolling. To do that, copy the C shell icon you just created by right-clicking on it and selecting ``Copy...'' and then choosing an appropriate destination folder (probably the desktop) for the copy. You can also copy the icon by pressing and holding the Ctrl key while dragging with the right mouse button. 8. Once you've made the copy, right-click on it and select ``Open'' and then ``Settings''. On the ``Session'' page, select ``OS/2 full screen''. Then go to the ``General'' page and type a new title: Title: Hamilton C shell Full Screen Page 8 Installation Close the Settings window for the copy by pressing Alt-F4. 9. All the material in the samples directory is provided for its tutorial value; you may or may not wish to copy it onto your hard disk. 10. Reboot your system before starting Hamilton C shell for the first time. This causes the new statements in config.sys to take effect. Page 9 Installation Installation as the Default Command Processor The C shell can also be installed as the default command processor OS/2 protected mode, meaning you specify it, not cmd.exe in your config.sys. The principal advantage is that when the when the C shell is run as the default command processor, PM allows the C shell to change its own title bar and, under OS/2 1.3 or 2.0 (but not the 6.167 Beta or LA builds), its own icon to show what it's running. This can be quite helpful if you have lots of copies of the shell running minimized and would like to know what each one is doing. The disadvantage is that the installation is slightly messy and it does disable cmd.exe's ability to change its title bar and icon. For these reasons, most users will want to wait until they've gained some familiarity with the C shell and with OS/2 before installing it this way. To install the C shell as the default command processor, follow the instructions for the basic installation but then make these changes, as appropriate for your system: Default Command Processor Installation Procedure (OS/2 1.2 or 1.3) 1. Edit the PROTSHELL line in your config.sys, replacing the pathname and any parameters for cmd.exe (remembering what they were) with the pathname for the C shell and a -L (login) parameter. The resulting line should look something like this: PROTSHELL=C:\OS2\PMSHELL.EXE C:\OS2\OS2.INI C:\OS2\OS2SYS.INI C:\OS2\BIN\CSH.EXE -L 2. Change the pathname you specify for the C shell in Start Programs or Group-Main to * (an asterisk). Also, change the parameters line to be either blank (1.1 or 1.2) or (1.3): /K "%*" 3. Change the entries (probably named ``OS/2 Window'' or ``OS/2 Full Screen'') in Group-Main or Start Programs for cmd.exe to fill in the complete pathname for cmd.exe instead of an asterisk. Set the parameters to whatever you had specified following the pathname for cmd.exe (if anything) in your config.sys before changing it in step 1. 4. Change any entries in any of your program groups which invoke .cmd scripts to run them via cmd.exe Page 10 Installation explicitly. For example, if you had an entry that specified the program ``c:\myapp\foo.cmd'', change that to: Path and file name: c:\os2\cmd.exe Parameters: /C c:\myapp\foo.cmd ...any additional parameters... 5. Reboot. Page 11 Installation Default Command Processor Installation Procedure (OS/2 2.0) 1. Edit your config.sys to set OS2_SHELL to point to the C shell, specifying the -L (login) option, e.g., set OS2_SHELL=c:\hamilton\bin\csh.exe -L 2. Modify the Settings for the OS/2 Window and OS/2 Full Screen icons to show the full path for cmd.exe (e.g., ``c:\os2\cmd.exe'') rather than an asterisk on the Program page. 3. Modify the Settings for the Hamilton C shell icons to specify an asterisk pathname (meaning the default shell), deleting any mention of any startup parameters and explicitly specifying the C shell icon rather than the default icon: a. Right-click on the icon and open the Settings. b. On the Program page, set Path and file name: * Parameters: c. Select ``Find...'' next to the icon display. d. Select ``Locate'' on the Find screen. e. Select the ``Path'' page on the Locate Folder screen. f. Type the pathname of the directory containing the C shell's csh.ico icon file. (E.g., ``c:\hamilton\bin''.) g. Press the ``OK'' button on the Locate Folder screen. h. Type ``csh.ico'' in the Name field on the Find screen. i. Press the ``Find'' button. j. The Find Results screen should appear with the C shell icon highlighted. Press the ``OK'' button. k. Back in the General Settings screen, you should now see the C shell's icon. Press Alt-F4 to close the screen. Page 12 Installation 4. When you reboot, the C shell will be the default shell and it will appear with its correct icon both for starting and when you minimize it. Page 13 Installation Page 14 Installation Installation on Windows NT This section describes how to install the Windows NT version of Hamilton C shell. System Requirements: Installation requires a 386-, 486- or Pentium-based machine for the Intel x86 version, a MIPS R4000- or R4400-based machine for the MIPS version or a DEC Alpha AXP-based machine for the Alpha version of Hamilton C shell. The machine must be running Windows NT build 404 (March 1993 Beta) or later. Roughly 2 MB of disk space is used on an Intel machine, 2.9MB on a MIPS or 3.5MB on an Alpha. Basic Installation: 1. Copy the contents of the bin and samples directories onto your hard disk, putting them anywhere you like. (Notice that the bin directory is too big to fit on one diskette; you'll have to merge the two or three diskettes, depending on which system you have.) 2. Copy the login.csh and startup.csh files into any directory you care to designate as your ``home'' directory. The significance of a home directory is principally that it will be convenient to specify pathnames relative to this directory. 3. Edit the login.csh and startup.csh files, customizing them to meet your needs. The login.csh file has a lot of comments in it which can take the shell a second or more to read each time it starts up; you'll almost certainly want to delete some of these comments once you've read them so the shell will start up faster. 4. Edit the environment variables by opening the Control Panel and then, within that, opening the system icon. To define a variable through the Control Panel, type the variable name in the ``Variable:'' fill-in box, the value in the ``Value:'' box and click on the ``Set'' button. Page 15 Installation a. Create or edit your entry for the PATH variable, adding the full pathnames for the C shell's bin and samples directories to the list. b. Create an entry for the HOME environment variable, setting its value as the full pathname of the directory where you placed login.csh and startup.csh. c. You may also want to include definitions for TABS and COLORS. The shell and all the utilities look for TABS to see if you want them to display text with tabs expanded out to something other than the default of every 8 characters. By default, the C shell displays white characters on a black background. The COLORS variable lets you choose a combination from this set: black, red, green, yellow, blue, magenta (or blue red), cyan (or blue green) and white. Foreground collows may also be bright, dim, blink or reverse. The keyword ``on'' introduces background colors. (Blink only causes true blinking full-screen; in a text window, it just makes the background brighter. Also, yellow is a true yellow only if it's bright. These are system limitations not related to the C shell.) Other color settings you might want to specify now or at some later time through the Control Panel are MOREPROMPT, MOREFILLIN and MOREERROR (for customizing the more utility's command line) and DELETIONS and ADDITIONS (for customizing the diff utility). For more information on setting screen colors, please refer to the the colors.csh file in the samples directory or to the Customization chapter. Here's an example of the settings you might specify: HOME=d:\doug PATH=d:\hamilton\bin;d:\hamilton;samples COLORS=white on blue TABS=3 ADDITIONS=bright white on green DELETIONS=bright white on red MOREPROMPT=red on white MOREFILLIN=black MOREERROR=bright white on red Page 16 Installation 5. Add csh.exe with the title ``Hamilton C shell'' to the Program Manager. To do this, pull-down ``File'' and select ``New''. A pop-up will appear asking that you confirm this will be a new Program Item. On the next pop-up, fill in: Description: Hamilton C shell Command Line: ....as appropriate....\csh.exe -L The ``-L'' part tells csh.exe when it starts up that it's a ``login'' shell, which means it should look for a login.csh file. 7. Logout of your Windows session and then log back in to cause all the new settings to take effect. Page 17 Common Problems Common Problems When I try to start the C shell in a new window, it dies and goes away before I can read its messages. You've probably made an error on the ``Parameters'' line under OS/2 or in the ``Command Line'' under NT. Under NT, select the icon for Hamilton C shell and press Alt- Enter to examine the properties. Under OS/2, you can force the window will to stay up after the shell exits so you can read the message by following the instructions appropriate for your system: OS/2 1.1: Go to the ``How to Run the Program'' screen by clicking on the C shell entry in ``Start Programs'' and pulling down ``Program'' then selecting ``Change...''. Click on the check box beside ``Close the window...'' and press Enter. OS/2 1.2 or 1.3: Click on the C shell entry in ``Group - Main'', pulling down ``Program'' and selecting ``Properties''. Push the ``Options...'' button and click on the check box next to ``Close window on exit'', removing the X. OS/2 2.0: Right-click on the icon and select ``Open'' followed by ``Settings.'' On the Session page, click on the check box next to ``Close window on exit'', removing the check. The shell doesn't know how to run an external command. One of the environmental variables, particularly HOME, PATH or COMSPEC is probably set incorrectly. Typical symptoms are that the shell doesn't seem to know how to find an external command or that it doesn't know how to run a .cmd file, etc. Another variation might be that it runs the old IBM more.com rather than the new more.exe. If you experience symptoms like these, first check that these variables are set sensibly. The other common possibility under OS/2 1.x is that you're using a network and have execute, but not read access to the application you're trying to run. Due to a bug in the OS/2 1.x kernel, the C shell cannot use the Page 18 Common Problems kernel's DosQAppType function to determine whether the application should be started full-screen, in a text window or as a PM graphics application. Instead, the C shell is forced to read the application's .exe header itself; if it can't read it, it can't run it. The solution is to be sure you have read access. Page 19 Common Problems The shell won't run my new program. Path hashing can sometimes produce surprising results if you create a newer version in your current directory of a command that already exists in another of your path directories. The shell won't know you've done this; its hash will still only list the older version. To overcome this problem, use either the rehash or unhash commands. The shell won't execute commands in the current directory. Your should add the current directory to the list of directories in the PATH variable. cmd.exe always checks the current directory before looking in any of the PATH directories. Hamilton C shell does not make this assumption; if you want the current directory to be first one checked, you should specify it explicitly as ``.'' at the beginning of the list. For example: setenv PATH = '.;c:\os2;c:\os2\bin' The shell keeps running the old version my shell procedure. If you define a shell procedure with proc in a .csh script file and then execute the script, the procedure is compiled into an internal form that's much faster to run and it's kept around in memory to make it run the next time even faster. If you change the text in the script file but don't explicitly throw away the old definition using unproc, the C shell won't know it's supposed to recompile. The shell won't run any cmd.exe internal commands. Most probably, the shell is unable to find your startup.csh file when it starts up. This is the file that should hold the aliases the shell uses to intercept cmd.exe's built-in commands. Check to see that your HOME variable is set to the directory where you've placed startup.csh and that your startup.csh file isn't garbled. When I start an application from the C shell, it dies immediately. Page 20 Common Problems Under OS/2, if you find that an application dies immediately after starting, check that the .exe file is properly marked with its type, i.e., full-screen, PM text windowable or PM graphics. The shell tries to start up an application in accordance with the way it's marked; if it's marked wrong, the application just won't run. Even very recently, a number of PM applications including even e.exe, the System Editor, were being shipped unmarked, which by convention is supposed to mean full-screen. To look at or change how an application is marked, use the markexe.exe utility. (Type ``markexe -h'' for help.) Another possibility is that the application has a bug that makes it fail if the maximum file handle count it inherits from its parent process is greater than 20. This problem has been seen in some past releases of the Microsoft linker (discussed below) and of WordPerfect, for example. You can force the C shell not to bump the file limit when it starts up using the -Z option but this option only works from the Start Programs (1.1) or Group (1.2) menus, not from the command line. (A process always inherits its initial maximum file handle count from its parent; from there, a process can only raise its own limit, never lower it.) The Microsoft OS/2 linker fails under the C shell even though it works fine under cmd.exe. Microsoft has determined there was a bug in the version of the C library used to build the link.exe distributed with MS C 5.1. The linker can fail if it's run as a child of a process that has a maximum file handle count greater than 20; this is a problem because the C shell sets its maximum to 255. If you're encountering this problem, try patching your link.exe file with the patchlnk.exe utility. (Type ``patchlnk - h'' for help.) When I try to run Microsoft's make.exe in the background it hangs. This is a known problem under OS/2 with make and certain other applications that need to spawn child processes of their own. The OS/2 process initialization and completion logic requests a semaphore in KBDCALLS.DLL that's already owned by whatever process in that window is already sleeping in a KbdCharIn call. Until another keystroke is pressed, that semaphore is never released and the background processes are never allowed to cleanly exit. This problem has been fixed in OS/2 2.0 and Page 21 Common Problems through CSD 5050 for OS/2 1.3 with a new KBDCALLS.DLL. That DLL for 1.3 is available on request from Hamilton Laboratories and can be downloaded from the listings area in the ``hamilton'' conference on BIX. copy or rename *.* doesn't work right. copy, xcopy, rename and del like to do their own wildcard expansion. To make them work sensibly, be sure your startup.csh file includes and that you use the aliases and procedure definitions we supply to intercept these commands to turn off shell wildcarding just long enough to run them. These definitions can also serve as a model if you discover other applications that must do their own wildcarding. For more information, refer to the discussion on page 85. The -! option doesn't work. The exclamation point is a special character for the shell. The shell lets you pick up text out of previous commands using history references that begin with ``!'' followed by a string that tells what text you're retrieving. To avoid having an exclamation confused as a history reference, be sure the exclamation is at the end of a word, so the next character is a space or a tab. grep '^foo' doesn't work. The circumflex has special meaning as the escape character to the C shell, even inside quotes. If you want to pass a literal ``^'' to grep (or anything else) from the command line, you must type ``^^'' unless the immediately preceding character was ``[''. When I list a directory over the network, not everything shows up. This is a known bug in the OS/2 networking code, not the C shell. The problem occurs if (1) the directory is read over a network, (2) directory entries are being read in blocks (for higher performance) rather than one-at-a- time and (3) the total number of characters in all the filenames in that directory happens to be just right. In all cases observed, adding or deleting any arbitrary entry in the directory makes the problem go away. The Page 22 Common Problems bug affects the C shell and its utilities because they use blocked reads; simpler programs like cmd.exe's DIR are unaffected because they read one entry at a time. The bug appears to have been introduced in IBM OS/2 EE CSD WR04098 and Microsoft Lan Manager 2.0, both issued around year-end, 1990. IBM has verified the problem and has developed a fix, which is now shipping as part of OS/2 EE 1.3. If you encounter the problem and you're an IBM customer, you should call 1-800-237-5511 or contact your local IBM representative and ask for a copy of the new netwksta.sys file being distributed as APAR IC02287. You can also download this file from the listings area of the ``hamilton'' vendor support conference on Bix or contact us directly and we'll mail you a copy. In the meantime, this release contains a work-around for disabling the block read feature. If you create an environmental variable, NETWORKBUG, and set it equal to 1, directory reads will be done only one-at-a-time, ensuring correct results at all times, albeit with some degradation in performance. You can do this either from the C shell: setenv NETWORKBUG = 1 or in your config.sys: SET NETWORKBUG=1 du, pwd and vol waste time sitting and spinning when they hit a removable drive that's empty. If you have a removable media device other than A: or B:, these utilities will normally try to report them. That's probably not you want, at least not usually; you can specify just the set of drives you do want reported using the DRIVEMASK environmental variable. Page 23 Common Problems cd /foo doesn't work. Hamilton C shell tries to serve users coming both UNIX and MS-Dos backgrounds. To do this, the C shell and all the utilities accept command line options to start with either ``-'' (UNIX-style) or ``/'' (Dos-style). It also recognizes filenames typed with either forward or backward slashes. But when you type ``cd /foo'', it guesses wrong and thinks you're trying to give it a command line option that it can't recognize. If this is really not what you intend, set the SWITCHCHARS environmental variable to just the specific characters you want recognized. E.g., you might include this in your config.sys to have only ``-'' recognized: set SWITCHCHARS=- I've just installed OS/2 1.2 and suddenly my environment variables don't work. The auto install program distributed with the fall, 1989 releases of OS/2 1.2 from Microsoft and IBM has a bug. It tries to automatically convert entries on the 1.1 Start Programs menu into corresponding entries on the new 1.2 Group Main menu. If the parameters line for starting a program has text on it (as the C shell's does), the entry is garbled even though it looks correct and causes a garbled environment to be passed to the shell. Editing the entry does not fix the problem. The only solution is to delete the entry and rekey it from scratch. I can't set my own screen colors. Yes, you can (finally, in this latest release.) But you cannot do it just by embedding ANSI escape sequences into your prompt since the C shell will immediately reset the colors back to what it thinks they should be. To set your own preferences for screen colors, you must use the COLORS environmental variable. See the chapter on customizing the shell or the colors.csh script in the samples directory for more information. The C shell's icon won't display in Group-Main. If you install the C shell as the default command processor by specifying it on the PROTSHELL line in Page 24 Common Problems config.sys and entering its path as ``*'' in Group-Main, you will see only the default OS/2 icon in Group-Main if you select View Icon. If you start, then minimize the C shell, it will have the correct icon, however. This has been reported to IBM. Their response is that, by design, when the path is an ``*,'' the Group code does not attempt to resolve the actual pathname (and whether there's any icon associated with it) until you actually click on the entry to start it. They agree this means you will not see the correct icon in the Group menu but claim this is what they intended and that it's not a bug. more crashes on the OS/2 2.0 Beta and LA Releases. The dynamic link library supporting 8514 displays in the beta and LA releases from IBM has a bug which causes some VIO applications, including more, to crash with a protection violation if they're run in a text window. They work fine full-screen. This problem has been fixed in the GA build. more hangs or exits prematurely on the OS/2 2.0 6.167 and LA releases. Under the 6.167 and LA releases, the 8514 display driver is completely unusable. It even has problems repainting the screen after a menu has been closed or displaying icons in the templates folder. It even causes more to hang the whole system if you have an 8514. But even using the VGA driver, random problems will be observed due, apparently, to bugs in the keyboard driver. Depending on what's fed to it through a pipe, more will occasionally prematurely exit after the first screenful. All these problems have been fixed in the GA release. The C shell can't change its title bar or icon under the OS/2 2.0 6.167 Beta and LA releases. This functionality was disabled in the 6.167 Beta and LA releases as part of the work to add the Workplace Shell. This problem has been fixed in the GA release. Alt-Enter doesn't work to grab commands from the history list under the OS/2 2.0 6.167 Beta Release. Page 25 Common Problems Under 6.167, Alt-Enter is gobbled up by the Workplace Shell as a keystroke combination used to signal that a VDM application should be toggled back and forth between the desktop and a full-screen session. If you type it anywhere else, it does nothing; it's not passed to the application. This has been fixed in the LA and GA releases. Under the 6.167 build, you'll have to type Ctrl-Shift-Enter instead. The C shell (and lots of other applications) only have default icons under the OS/2 2.0 6.167 Beta and LA Releases. The Workplace Shell does not support .ico files. All icons for text applications must be stored in the extended attributes. The latest builds of the C shell have the icon both in the EA and in an .ico file but if you copied the C shell onto your disk with a utility (e.g.., something other than cp) that does not support EA's, that information probably got lost. To put an icon into the extended attributes, use the OS/2 1.3 File Manager, selecting the file, pulling down ``Properties'' and selecting ``Icon...''. I just installed the C shell as the PROTSHELL and now when I start Commmunications Manager, it dies immediately. Communications Manager is invoked via a .cmd script file. Follow the instructions in step 4 on page 10 to rewrite that entry to start that script explicitly via cmd.exe. I can't wildcard filenames with $, quoted or escaped characters in them. Yes, you can (finally, in this latest release.) To do so, just quote or escape the special characters. E.g., to get all the files that begin with $, you might type ^$* or '$'* . I can't run the C shell inside an Epsilon editor window. The Epsilon editor tries to run whatever command processor you use by creating a full-screen session and Page 26 Common Problems doing a KbdRegister to intercept the KbdStringIn API entry so that Epsilon can feed it whatever you type in the editor window. Output (stdout and stderr) from the child session is redirected over a pipe back to the editor. There are a couple problems in their approach: (1) They neglected to consider that not all applications use KbdStringIn; if stdin is attached to a keyboard, the C shell reads a keystroke at a time using KbdCharIn and those calls still end up tied to that full-screen session rather than being redirected. (If stdin is attached to anything else, it uses DosRead calls.) The authors of Epsilon really should have intercepted the whole set of Kbd calls, not just one of them. (2) Not all applications write their output to stdout or stderr; applications like more, that use Vio output, won't run properly. Their output appears in that full-screen session, not back in the editor window. Epsilon really should be doing a VioRegister to grab the Vio output also. We are working with Lugaru Software (the authors of Epsilon) on a solution that should be available shortly. A partial workaround is to tell Epsilon to use a separate program, which just reads input and pipes it to the C shell. Marty Klos at IBM has written a small C program to do that and placed it in the public domain. A copy is available on request from us or may be downloaded from the listings area of the ``hamilton'' vendor support conference on BIX. rm doesn't remove anything, it just puts everything in a hidden directory. You're using the notorious Microsoft rm command instead of the Hamilton rm. The Microsoft rm doesn't remove anything; it just puts things in a hidden system directory. Hamilton rm is actually in hrm.exe under Windows NT and should be aliased to rm in your startup.csh file. Fix that and then, to get rid of all those ``deleted'' directories: cd \; rm -x `ls -1ra +H | dim | grep 'deleted$'` Page 27 Common Problems Page 28 Product Support If you encounter problems or would like to make suggestions for a future revision, please contact us by any of the following or by regular mail; we promise a prompt response. Phone: 508-358-5715 FAX: 508-358-1113 MCI Mail: 389-0321 Telex: 6503890321 BIX: hamilton CompuServe: 70034,2025 Internet: 3890321@mcimail.com Also, on Bix, we have a vendor support conference. Do a ``join hamilton'' once you get on or follow the menus into the conference system. Bug Reports If you encounter what you believe to be a bug, please try to experiment to see what specific command or command sequence seems to be failing before calling. A problem that's easily reproducible is obviously easier to fix. Built in to Hamilton C shell are a number of consistency checks to trap bugs before they cause damage and to snapshot enough information to help us diagnose and repair the problem. If the shell is actually crashing, look to see if a new entry has been added to the error log, crash.csh, in your home directory; that information will be useful. When you call, we'll try to provide an immediate workaround if there is one. If the problem is serious but straight-forwardly correctable, we can generally offer an interim release at no charge to fix that specific problem. At the very least, we try to schedule it for an upcoming general release. Future Enhancements Work continues on additional features and enhancements. As they become available, we want you to have them. Page 29 Support Please return the registration form by mail or FAX. Without that, we often have no way of knowing who you are to send updates to. This is particularly true if your copy was purchased through your company's purchasing department or through a retail distributor. Also, we look forward to your feedback as we strive to improve the product. Page 30 Page 31 User Guide User Guide Getting Started Starting Hamilton C shell is simple: select it from the Start Programs window or the Program Selector or type ``csh'' as a command to cmd.exe. After the initial greeting, you'll see the first prompt: (The underscore is meant to be the cursor.) Hamilton C shell(tm) Release 2.1 Copyright (c) 1988-1993 by Hamilton Laboratories. All rights reserved. 1 D% _ This tells you that it will remember what you type as command number 1 and that your current drive is D. The ``%'' is traditional; rather like the ``>'' for DOS. Naturally, you can change your prompt if you want, to be anything you like. For example, to get a prompt that looks like one you might get from cmd.exe+: 1 D% set prompt1 = '[$upper(cwd)] ' [D:\DOUG] _ This works by taking the value of the cwd (current working directory) variable, turning it to upper case using one of the built-in procedures and pasting left and right brackets around it. The value is recalculated each time a prompt is given, so it always displays an up-to- date value. (Lists of all the built-in variables and procedures are given in later sections.) To set it back: [D:\DOUG] set prompt1 = '$@ $CDISK% ' 3 D% _ ____________________ + We introduce this is as the first example with some trepidation: the prompt seems to be the first thing people want to change. But it can also be one of the more daunting projects if you're getting started. This example is offered more in the spirit of assurance that, with a little experience, the prompt can be set to anything you like. Page 32 User Guide Basic Statements Generally speaking, whatever commands you might have typed into cmd.exe will still work here. Even an ``internal'' cmd.exe function like dir works: 3 D% dir The volume label in drive D is USER. Directory of D:\DOUG\SH\DOCS\SCRIPT\HELLO . <DIR> 2-23-89 2:13p .. <DIR> 2-23-89 2:13p HELLO C 72 2-23-89 12:56p HELLO EXE 7731 2-23-89 12:57p MEMOS <DIR> 2-23-89 1:46p 5 File(s) 1581056 bytes free 4 D% _ If the command you type refers to a .cmd batch file or a cmd.exe internal function, Hamilton C shell passes it to a child process running cmd.exe for evaluation. (cmd.exe's built-in functions are intercepted with aliases defined in your startup.csh file.) Everything else is evaluated directly by Hamilton C shell. For example, if you type the name of an .exe file, the appropriate DosExecPgm( ) or DosStartSession( ) call to the OS/2 kernel or CreateProcess( ) call to the NT kernel to start that program will be done directly by Hamilton C shell. A bit-mapped hash mechanism is used so that when you type the name of a command, the shell zeroes right in on file you mean. It doesn't have to check every path directory for every possible extension. Naturally, if you type a command that doesn't exist, the shell complains: 4 D% zork csh: Couldn't find an executable file named 'zork'. By being more than merely a ``wrapper'' around an existing command processor, several advantages are created: (1) performance is understandably (and visibly!) much higher and (2) limitations on command line lengths, etc., become the relatively generous limits of OS/2 and NT, rather than the restrictive limits of cmd.exe. Customizing the Screen Colors Page 33 User Guide The C shell's default screen colors are white characters on a black background. Highlighting and color are used to make some things (special files, etc.) stand out. All the use of color or highlighting is completely customizable. You can choose anything you like. The chapter on customization will go into this in detail, but for now, let's suppose we'd simply like to pick something a little easier on the eyes, like white characters on a blue background: 5 D% setenv COLORS = white on blue Command Line Editing With command line editing, you'll notice immediately how much easier it is do things quickly without a lot of retyping. As you try the examples, notice how the arrow, insert, delete, home, end and other keys can be used to recall previous commands or make changes anywhere on the line. Command line editing is like having a full-screen editor pasted onto the front end of the shell. Key bindings are intuitive and follow accepted conventions. You can create enormous commands that stretch over screen after screen and move around with the arrow keys, inserting or deleting anywhere. Watch changes ripple almost instantly down even an entire screenful of text. We think you'll find our command line editing superior to anything you've seen or used elsewhere. The basic key assignments are: <Insert> Toggle between insert and overstrike modes. (The cursor is thicker when you're inserting.) <Home> <End> Beginning/end of command line. <Left> <Right> One character left/right. <Up> <Down> Up/down one command in the history list. Pressing Ctrl with the arrow keys lets you move by words or lines. Pressing Alt instead does word or line deletion. (The convention we follow is that the Alt key is a little ``more powerful'' than the Ctrl key.) What you last deleted is kept in a scrap buffer and can be pasted back elsewhere. To paste something from Page 34 User Guide the scrap buffer back into the command line, move the cursor to where you want it done and press: Ctrl-<Insert> Paste one word at a time. Alt-<Insert> Paste the whole thing. Command Completion In addition to backing up through your previous commands one at a time with <Up> and <Down>, you can also ask the shell to search back through any previous commands you've typed for the last command that either started with or contained the characters in the previous word. Ctrl-<Enter> means ``look for a command that started with ...,'' and Alt-<Enter> (again, a little ``stronger'') means ``look for a command that contained the string anywhere.'' (On NT, it's necessary to type Ctrl-Shift-<Enter> because Alt-<Enter> is grabbed by the system to mean switch to full-screen.) Repeatedly pressing these keys cycles up through all the matching commands you've previously typed. Command completion uses something called the history mechanism to recall commands you've previously typed. Later, we'll devote a whole chapter to some of the more advanced uses of history. Page 35 User Guide Filename Completion Filename completion is another ``creature comfort:'' you type just a fragment of a filename and let the shell fill in the rest. The two variations are using the F key for basic filename completion or the D key if you want all the duplicates listed. Alt-F or Ctrl-F Filename completion. Look for a filename that starts with preceding characters. If it matches a single file, fill in the rest of the name. If more than one file matched, show the part that was the same for all, highlighted in green. (Bright red means there were no matches at all.) Alt-D or Ctrl-D Duplicate completions. Show any/all matching filenames, one after the other with spaces between. Filename completion is actually done with wildcarding. Unlike cmd.exe, Hamilton C shell does any wildcarding before excuting the command you type. It uses a powerful recursive pattern match algorithm that guarantees sensible matches even if you type a very complex pattern. Wildcarding is the subject of a whole chapter up ahead. The Tour Begins Here The following chapters introduce the various facilities Hamilton C shell provides, starting with some of its basic vocabulary: the simple utilities that come with it. Following discussion shifts to the intrinsic, internal functions provided by the shell itself: i/o redirection, pipes and command substitution; the history mechanism and wildcarding. Intermediate level discussion follows, describing expressions, variables and aliases and the editing and quoting facilities. The process and thread scheduling mechanism is described, outlining how an activity can be placed in the background. The tour will then cross the threshold from discussion of individual statements to discussion of structures of Page 36 User Guide statements. Structures for iteration and condition- testing and procedural abstraction will be introduced. Finally, we'll wrap up with discussion of how to customize the shell together with a section detailing specific compatibility issues between the Hamilton and original Berkeley C shells. Page 37 User Guide The Utilities Hamilton C shell comes with a lot of utilities that form some of its vocabulary. They do small, but oft- needed functions, often in a novel, faster or more convenient way than you'd find in ``plain vanilla'' OS/2 or NT. This section provides a quick tour, outlining some of the capabilities and conventions. ls: List files ls is a somewhat nicer way to list a directory: 6 D% ls memos hello.c hello.exe sysstuff Subdirectories are highlighted (shown here in bold.) If a file or directory has the system bit set, it's still listed, displayed in green (shown here in italic.)+ Normally, ls lists everything in lower case for better readability. In long format: 7 D% ls -l D---- Feb 23 13:46 - memos ---A- Feb 23 12:56 72 hello.c ---A- Feb 23 12:57 7731 hello.exe -S-A- Feb 23 13:22 15 sysstuff Conventionally, ls lists things alphabetically, with directories ahead of files. There might be hidden files or directories, but to see them you have to ask: 8 D% ls +H memos hello.c hello.exe hiding sysstuff Conventions To find out how any of the utilities work, just use the -h option. For example, 9 D% ls -h ____________________ + All our examples will be given in terms of the default screen colors. But these are easily changed to your own preferences. See the chapter on customization or the colors.csh script file in the samples directory. Page 38 User Guide tells about options for more detailed listings, sorting the list by date or by size, selecting only certain types of files, etc. ls is a read-only activity; it never makes any changes to the file system. Lists are always sorted in memory; its speed and flexibility completely obsolete the old (and dangerous) ``directory sort'' utilities popular on DOS. The names of the utilities were chosen to be consistent with the names of similar functions on UNIX, where they provided much of the vocabularly of the original UNIX C shell. But changing the name of a utility is a simple matter: just rename the corresponding .exe file or, better still, create an alias (discussed later.) By convention, the utilities expect options to come ahead of any files you specify. Options are case- sensitive. We've tried to use mneumonic letters for options (e.g., h for help) and to use the same letter to mean the same thing across related utilities; achieving that is simply more feasible with 52, not just 26 characters to choose from. Our examples generally show options introduced with ``-'', but you could equally well follow the DOS-style convention of using ``/'' if you prefer. If indeed you want only ``-'' or only ``/'' interpreted as an option character, this can be set with the SWITCHCHARS environmental variable, which can be set either from the C shell or from your config.sys file on OS/2 or from the Control Panel on NT. Sadly, it won't have any effect on the standard OS/2 or NT commands like dir or xcopy or on applications you purchase elsewhere, but it will work on all the commands supplied with the C shell. For example, to have only ``-'' recognized as an option character, you might type this into the C shell: 10 D% setenv SWITCHCHARS = - or put this into config.sys (rebooting to make it take effect): set SWITCHCHARS=- You can type options in any order (except where one overrides another, in which case the last setting is used) and you group them together or type them separately as you choose. For example, ``ls -L -d -w'' is exactly the same as ``ls -dwL'' and produces a very long format (very detailed) list of the current directory, sorted by date (newest ones last), with sizes of any directories filled in by walking down through the directory tree, adding up all the sizes of all the files found there. Page 39 User Guide You can always unambiguously end the options with ``--'' in case you have a filename or an argument string that begins with one of option-introducing characters. Also, since the shell does the wildcard expansion, it's a bit more convenient and faster for the utilities to look for any options right at the beginning of what could be a very long list (up to 64 kilobytes) of filenames or other command-line text. We'll always follow the OS/2 and NT convention of using ``\'' in filenames in this book and we generally advise that you do too, not so much because the C shell cares but because so much other OS/2 and NT software does. To some fair degree, it's a case of ``when in Rome, doing as the Romans do.'' But if you really do prefer, you can generally use ``/'' with the C shell and all the utilities. Do remember, however, that if you type a filename starting with ``/'' to mean the root, you have to be careful that it can't be confused as the start of an option. (This is a good use for the ``--'' option or the SWITCHCHARS variable.) Page 40 User Guide echo echo is a little different than the vanilla OS/2 or NT echo. It does only one thing: it prints whatever arguments words you give it; there's no echo on or echo off-style status reporting function. But it does offer much finer control over what gets printed: you can write binary values, choose not to append a new line and write to stderr instead stdout. Here's an example where the ANSI escape sequences turning brightness on and off are embedded into a string being echoed. The ANSI escape character is octal 033; binary values or special characters like ``['' are introduced by the ``^'' shell escape. 11 D% echo Have a ^033^[1mnice^033^[0m day. Have a nice day. (Processing of the ^ escape sequences is done by the shell before any command ever sees it. As a result, you can use escape sequences to construct command line arguments for any command; this feature is introduced here only because it tends to be most often used with echo.) mv, cp and rm: Move, copy and remove The mv (move), cp (copy) and rm (remove) trio allows files and directories to be treated as simple objects. mv will move either files or directories treating them simply as objects, even across disk partitions. In this example, the two hello files are moved into a new directory, illustrating how mv understands that if there's a many-to-one relationship, the destination has to be a directory. 12 D% mv hello* hello 13 D% ls hello memos sysstuff 14 D% ls hello hello.c hello.exe Similarly, cp will copy a file or even an entire directory. The copies cp produces are always exact Page 41 User Guide logical copies, with correct timestamps+ and attribute bits and including any hidden or system files. 15 D% cp hello newhello 16 D% ls hello memos newhello sysstuff 17 D% ls -l hello ---A- Feb 23 12:56 72 hello.c ---A- Feb 23 12:57 7731 hello.exe 18 D% ls -l newhello ---A- Feb 23 12:56 72 hello.c ---A- Feb 23 12:57 7731 hello.exe cp does not consider it an error to copy over an existing file unless the file about to be overwritten has its read-only bit set. Finally, rm can be used to remove a file or even an entire directory. But it does insist that you tell it you really mean it if you ask to remove a directory that's not empty or anything that's marked with the system bit. 19 D% rm sysstuff rm: Can't remove system file 'systuff' without -S option. 20 D% rm -S sysstuff 21 D% ls hello memos newhello 22 D% rm newhello rm: Can't remove non-empty directory 'newhello' without -r option. 23 D% rm -r newhello 24 D% ls hello memos As you can see from these examples, the general style of the utilities is fairly terse. Like the proverbial Vermonter, they don't say anything unless they've got something to say. Even copying or removing a directory happens without fanfare as long as the appropriate ``yes, I really mean it'' options are supplied. more more is an especially fast browsing filter. There are two ways to use more. The first is in a pipeline, the ____________________ + Files only under OS/2 1.1. New directories always get the current timestamp unless you're running OS/2 1.2 or later. Page 42 User Guide way ``vanilla'' more might be used when you suspect the data may be longer than a screenful: 25 D% ls -l c:\os2\bin | more : : If the output turns out to be less than a screenful, it's as though you'd just typed the ls command by itself. In fact, there's not even a noticeable performance penalty. But if it's more than a screenful, more switches to an interactive mode where you can use the arrow keys, etc., to browse up and down through the listing. more can also be used for browsing a list of the files you give it on the command line: 26 D% more *.c more incorporates the Berkeley notion referred to, tongue-in-cheek, as ``more is less+'': it's a good paging filter that lets you go forwards and backwards. It also offers a number of different ways of looking at or searching the data including binary, as control characters, line-numbered, etc. Perhaps most important, it's fast. Part of more's speed comes from an internal cache of about 11K characters of text coupled to an indexing structure that it builds on the fly as it reads the input. When you move forward or backward within the cache, screen redraw rates are the limiting factor in performance. Outside of range of the cache, if the input is from a disk file, the indexing structure, technically an ISAM, tells more how to seek to the new location. There is also a ``huge'' version of more, called moreh, that was compiled in large model and while slightly slower, has the advantage of caching up to about 4M characters. moreh can be useful when speed is less important than being able to scroll all the way back through a large amount of text coming through a pipe. touch ____________________ + The story is now a part of computer folk history: at first, more only went forward. Then someone created a filter that went backwards, which he aptly named less. When later versions of Berkeley's more incorporated this feature, they were heralded by announcements that, finally, ``more was less.'' Page 43 User Guide touch lets you change the timestamps of individual files or directories+ or, using the -r (recursive) option, of everything in a whole directory tree. If the desired timestamp isn't given, touch uses the current time. If the filename doesn't exist, it's created as a zero-length file. 27 D% ls hello memos 28 D% touch zork 29 D% ls hello memos zork chmod chmod lets you set a file's attributes but leaves the timestamp alone. Here is an example, first setting the system bit (making it show up in green), then making it hidden: 30 D% chmod +S zork 31 D% ls hello memos zork 32 D% chmod +H zork 33 D% ls hello memos Of course, the file is still there and you can continue to manipulate its attributes: 34 D% ls -l zork -SHA- Feb 23 13:16 0 zork 35 D% ls +a . hello zork .. memos 36 D% chmod +R zork 37 D% ls -l zork -SHAR Feb 23 13:16 0 zork Many users will find that a file's system bit is more useful than they'd thought before. With chmod, it's easy to set or clear the bit and setting it doesn't make the file hidden. Quite the contrary, ls makes it stands out in green. Also, a file marked ``system'' is a little safer from accidental deletion or overwriting. These are ____________________ + On an OS/2 1.1 or Windows NT system, the kernel allows you to change the timestamps only on files, not directories. touch'ing a directory does nothing unless you use the -r option to recursively touch the directory's contents. Page 44 User Guide often convenient characteristics to attach a few specific files within a large directory. For example, the author tends to routinely mark make files within a C source code directory as ``system'' just so they'll stand out. du, vol and pwd du, vol and pwd provide quick snapshots of your disk partitions: du tells how much of the partition is used; vol displays the label; and pwd shows the current directory on each partition. 38 D% du c: 31.904 M Total = 29.465 M Used + 2.439 M ( 7.65%) Free root d: 23.920 M Total = 22.438 M Used + 1.482 M ( 6.20%) Free user e: 13.957 M Total = 8.520 M Used + 5.438 M (38.96%) Free misc 39 D% pwd c:\os2\include d:\doug\sh\docs e:\tmp 40 D% vol c: Jan 24 22:32:10 1988 root d: Nov 27 20:34:58 1988 user e: Jan 17 17:12:20 1988 misc A common convention observed by the utilities is that if one entry on a list is more current or special than the others, it's highlighted. du, vol and pwd each highlight the entry describing the current disk. For the benefit of those who have lots of partitions, some of which they don't want to bother listing all the time, du, vol and pwd look for a DRIVEMASK environmental variable which can be used to mask off just the drive you want. This is especially useful for excluding drives that take removable media; if they're empty, they can waste a lot of time trying to read a diskette that's not there. dirs, pushd, popd and rotd The shell provides a built-in mechanism for keeping several directories ``handy.'' This mechanism is the directory stack, which always contains a list of fully- qualified directory pathnames with the current directory at the top. You can display the list with the dirs command: Page 45 User Guide 41 D% dirs d:\doug\sh\docs Initially the list contains only your current directory. When you push a new directory on the stack with pushd, that becomes your new current disk and current directory. pushd also reports the resulting stack contents. 42 D% pushd c: c:\os2\include d:\doug\sh\docs 43 C% pushd e: e:\tmp c:\os2\include d:\doug\sh\docs Calling pushd without any arguments just swaps the top two directories: 44 E% pushd c:\os2\include e:\tmp d:\doug\sh\docs Popping elements off the stack is done with popd, which also reports the resulting stack. 45 C% popd e:\tmp d:\doug\sh\docs The stack can also be rotated with rotd. (We'll push another directory first so we can see that rotation is upward, with the top item going to the bottom of the stack.) 46 E% pushd \ e:\ e:\tmp d:\doug\sh\docs 47 E% rotd e:\tmp d:\doug\sh\docs e:\ You can pop multiple directory entries at once, but if you ask to pop more than exist, you'll get a message: 48 E% popd 5 csh: The built-in popd command can only accept a integer argument n, where n > 0 && n < number of elements on the directory stack. The default for n is 1. Page 46 User Guide 49 E% popd d:\doug\sh\docs e:\ fgrep and grep fgrep and grep are fast string search utilities. Their names and the regular expression syntax are traditional; it's an accepted standard and we've followed it. fgrep and grep are used to scan through long lists of files or filter data coming through a pipe for strings or patterns you specify. They'll quickly report all the matching lines. If you like, you can get more or less detail in the output, e.g., have line numbers shown or just get a total count of all the matches. fgrep and grep both have the ability to look for a large number of patterns in parallel (using the -s or -f options) with almost no discernable performance degredation. They're very fast. Both precompile and optimize their search patterns, use direct kernel api calls for all i/o and use a very high performance buffering structure to allow extremely fast scanning of large amounts of data. fgrep fgrep is the simpler and slightly faster of the two search utilities. It does a simple string compare between the string you're looking for and the characters on each line. If the search string is found anywhere on the line, it's a match. There are some options for ignoring differences in upper-/lower-case or in the amount of white space (spaces and tabs) between words but but mostly it's quite simple comparison. Here's an example of using fgrep to search a very simple personal phone directory where each record is just a line of text and we'll search it . (Later we'll learn how to package things like this up into aliases or shell procedures so you can call them with just a few keystrokes.) 50 D% fgrep -i doctor \phone Doctor James Gardner 508-999-0000 12 Canton St Doctor Karen Strickland 508-721-1223 N.E. Medical Offices Page 47 User Guide grep grep looks for special patterns called regular expressions, which are similar to (but slightly different from) filename wildcarding. The grammar is recursive, meaning a regular expression to be matched can be written, in turn, as a nested series of regular expressions: c Any ordinary character matches itself. \c Match the literal character c. ^ Beginning of line. $ End of line. . Match any single character. [...] Match any single character in the list. [^...] Match any single character not in the list. \n Match whatever literal text the n'th tagged $...$ expression matched. r* Match zero or more occurrences of r. r1r2 Match expression r1 followed by r2. $r$ Tagged regular expression. Match the pattern inside the $...$, and remember the literal text that matched. At the lowest layer, you give a character or set of characters to be matched anchored, if you want, to match just the beginning or just the end of a line. At the next layer, the ``*'' character lets you match a variable number of repetitions of a pattern. When you type a regular expression on the command line, keep in mind: (1) Many of the characters have special meaning to the C shell and have to be inside quotes. (2) You have to type two ``^'s'' to get just one because ``^'' is the shell's literal escape character. (3) ``*'' is a postfix operator. It operates on the preceding regular expression; by itself, it is not a ``match zero or more characters'' wildcard character as you may be used to with filenames. Here's an example of searching through all the source code for a large application, looking for all occurrences of lines that begin with ``statement'' followed by a ``y'' somewhere on the line and showing the line numbers of any matches. (The -s option tells pushd and popd to work silently.) 51 D% pushd -s ~\sh 52 D% grep -n '^^statement.*y' *.c allocate.c:418:statement_obj *allocate_statement(size, type) 53 D% popd -s Page 48 User Guide sed sed is a stream editor. Just as you might think of using a regular editor to edit a file, deleting or inserting lines, doing search/replace operations, etc., sed lets you edit a stream of data: individual lines are read from stdin, edited according to the script you give and written to stdout. A very simple sort of script might be given right on the command line. Here's a simple search/replace: 54 D% echo hello world | sed s/world/everybody/ hello everybody sed uses the same regular expressions used by grep. It's possible to pick up pieces of the input as tagged expressions and move them around. In this example, the two strings on either side of the space are tagged, then swapped around. Quotes are used around the search/replace command so the C shell will treat it as one long literal string to be passed to sed. (Parentheses, spaces and asterisks otherwise have special meaning.) Notice how the ``*'' construct, meaning match zero or more occurrences actually matches as many repetitions as possible. 55 D% echo hello world | sed 's/$.*$ $.*$/\2 \1/' world hello For more complex operations, sed offers a wide array of operators including even conditional branches and a hold buffer where a string can be saved temporarily from one line to the next. If your script is very long, the -f option lets you specify it in a file. diff diff is an extremely fast and flexible utility for quickly comparing ascii files, looking for differences. In the simplest form, you simply give it two filenames corresponding to the old and new versions and let it go to work, reporting sections that have been deleted or added in a traditional format. For example, as a software developer, I might use it to compare old and new versions of a C program: 56 D% diff archive\parse.c parse.c 1493 c 1493 < d->inline_cnt = src->inline_cnt++; --- > d->inline_cnt = ++src->inline_cnt; Page 49 User Guide Each change is reported in terms of the line number or range in the old version, whether it's an addition, change or deletion, the line numbers in the new version and then the affected lines from each file, separated by a line of ``---''. diff supports the traditional options for ignoring differences in upper-/lower-case or in the amount of white space on the line, for recursively comparing entire directory trees of files, etc. One of diff's most novel features is its ability with the -! option to generate a merged listing where text that's deleted is shown in red, new text is shown in green and the rest is displayed normally. This makes it extremely easy to view your changes in context. (To use this option, remember that ``!'' is a special character to the shell; type it at the end of the option list so there'll be a space following.) head and tail head and tail are used to display just the first or last few lines or characters of a file. Normally, they expand any tabs into spaces so you don't need to filter them through more. tail is particularly interesting. If all you want is the end of a very large file, tail doesn't waste time reading the whole file from start to finish. Instead, it jumps right to the end and reads it backwards! If the file is truly large (on the order of several megabytes) and all you want is a little bit off the end, this is the difference between chugging along for several seconds versus getting an almost instantaneous response. tail also has a -f follow option. What that means is that when it gets to the end of file, it enters an endless loop, sleeping for a second, then waking up to see if more has been added. This is particularly useful if, e.g., you have an operation, say a large make, active in one window with its output redirected to a file. From another window you can periodically check in on the progress by typing: 57 D% tail -f e:\tmp\make.log : ^C tail lets you watch lines get added without consuming much processor resource (since it sleeps in the kernel most of the time) so you can watch a background activity Page 50 User Guide progress without affecting its performance. After you've watched for a while, just type ^C to interrupt and get out. The interrupt only goes to the tail program; the application off in the background or in another window creating the file is not affected and will go on about its business until you come back once again to check on it. cut cut is a simple filter for selecting out just certain fields or character positions of each line of input. You choose what characters should be interpreted as the field delimiters and which fields should be copied to the output. For example, if you kept your phone book in \phone, you might strip off just the first word from each line to get everyone's first names: 58 D% cut -f1 -d' ' \phone Ed Helen Jack Vickie : The -f option means you want to count by fields, selecting the first field and that the delimiter is a space character. (Notice the quotes around the space.) Page 51 User Guide split split lets you break up a large file into smaller, fixed-size pieces counting either by lines or by characters. Each of the smaller files it creates are numbered, e.g., chunk.001, chunk.002, chunk.003, etc. One example of where you might use split might be if you had a very large file you wanted to transmit over a modem. If the line dropped suddenly, you wouldn't want to have to start all over on a 2M file. If you split it first into 200K chunks, you'd stand to lose a lot less. Another example might be if you had a truly enormous text file that was just too big to easily edit with your favorite editor. Splitting it up into chunks of only 10K lines each might be a solution. tabs tabs lets you expand or unexpand tab characters based on a set of tab settings you give it. Tab settings are religious. I like them every 3 spaces but you probably like something else. If you're composing something to be sent as email or posted on a bulletin board, it's probably nice to expand it out before you send it so everyone sees what you see. tr tr is a another simple filter for translating characters from input to output. For example, you could translate everything from lower to upper case by typing: 59 D% tr a-z A-Z hello world HELLO WORLD ^Z We typed the first hello world and tr has just echoed it in upper case. ^Z is the end-of-file character defined by OS/2 and NT. tr also has a number of options for squeezing out repeated sequences of the same character or editing out just certain characters and even for normalizing the text in a file, ensuring that every line ends with a carriage return/line feed combination. That's handy if you're importing a file from another operating system. Page 52 User Guide strings strings lets you simply list out all the ASCII strings in an otherwise binary file. Sometimes this can be useful for spelunking around through a file when you're really not sure at all just what's inside it. Various options are available to trimming the output so only strings of a minimum length, etc., will be shown. For example, 60 D% strings hello.exe !This program cannot be run in DOS mode. : Hello, world : Another example might be if you suspected an application was carrying a virus. Naturally, strings can't guarantee something's free of any virus, but on the other hand, if you scan it with strings and find something like this, obviously you should be careful: 61 D% strings a:suspect.exe : Aha! Gotcha! I just blew away your hard disk! dskread and dskwrite+ This pair of utilities can be used to quickly copy, format or mass duplicate diskettes in a single pass. Here's an example using dskread to read a whole diskette image onto your hard disk and then write it back out onto a new floppy with dskwrite. The dskwrite -a option means autoformat, i.e., if the new disk isn't already formatted, format each track as it's written. The -v option means read back and verify each write to be sure a good copy was made. 62 D% dskread a: >disk.image # Read the whole diskette 63 D% dskwrite -av a: <disk.image # Make a new copy To make more copies, you simply keep putting new diskettes in and rerunning the dskwrite. Since the entire diskette image, including the boot sector is captured onto the hard disk by dskread, it's possible to email a bootable diskette image, even compressing it first with one of the popular compression utilities such as arc or pkzip. ____________________ + Dskread and dskwrite are not available as of this writing for Windows NT but will be soon. Page 53 User Guide dskread and dskwrite can also be used to copy a very large file onto a whole series of diskettes and restore it later as a single file. E.g., to back up your hard disk, you might compress whole directories using one of the popular compression utilities and write the resulting archive file out as 1.2MB (or, as appropriate, 1.4MB) chunks onto separate diskettes. To restore the file, just cat or dskread the pieces together again. (But if you do try this, be sure the compression utility you use can handle any long filenames or system or hidden files you have lurking in your directories.) Here's an example of writing a very large .zip file to a series of diskettes. The -c option means it should continue with as many diskettes as it takes to hold all the data, prompting you for each new diskette when it needs it. The -d option causes it to write a dummy file system around the data (so it still looks like a regular OS/2 or NT diskette). The -n option takes an argument specifying the name given the file being created on the diskette. In this example, the first diskette will have a file named ``big.001'', the second will have ``big.002'', etc. Once again, the -av options mean autoformat and verify each write. 64 D% dskwrite -avcd -n big a: < g:big.zip To get it all back, you could simply copy all the pieces individually onto your hard disk and then cat them together or use dskread to do it for you: 65 D% dskread -dc -n big a: > g:big.zip Other Utilities Other utilities provide means for sleeping for a timed period, counting the number of words in a file and so on. Part of the appeal of Hamilton C shell is that it's relatively easy to continue expanding the vocabularly with simple utilities that may each be only a few hundred lines long. This has been a fast introduction. Fortunately, you don't have to learn the utilities just from the book. All have on-line information available with -h. We encourage you to experiment. As this is being written, we're still giving thought to additional utilities. If you have favorites you'd like to see included or maybe offered as new products, please contact us. Page 54 User Guide I/O Redirection and Piping I/O Redirection You can redirect or pipe i/o in much the way you might under cmd.exe. Here's a simple example redirecting stdout from the word count of the famous ``Hello, world'' program. cat just copies from any files you tell it or, by default, from stdin to stdout. 66 E% cd hello 67 D% ls hello.c hello.exe 68 D% cat hello.c #include <stdio.h> main () { printf("Hello, world.\n"); } 69 D% wc hello.c >hello.wc 70 D% cat <hello.wc 5 8 72 hello.c (wc tells us that hello.c has 5 lines, containing 8 words, totalling 72 characters.) If the file you write to with ``>'' exists, it's first truncated to zero length (discarding the old contents); if the file doesn't exist, it's created. With ``<'', it's an error if the file doesn't exist. Data can be appended to a file with the ``>>'' operator: 71 D% echo that^'s all folks >>hello.wc 72 D% cat hello.wc 5 8 72 hello.c that's all folks 73 D% _ When you append with ``>>'', if the file exists, data is written onto the end; if it doesn't exist, it's created. (The single quote character has special meaning to the shell on the command line; the special meaning is turned off by the shell's escape character,``^''.) Page 55 User Guide noclobber Not everyone is comfortable with letting the shell glibly toss away an existing file if you type ``>'' when you meant ``>>'' or lose it somewhere if you mistype an existing filename with ``>>''. The noclobber variable lets you tell the shell you want this to be caught, so you can decide if this was really what you meant. If you set noclobber, you have to type ``>!'' to redirect to an existing file: 73 D% set noclobber = 1 74 D% echo trash this file > hello.c csh: Couldn't open 'hello.c' as a redirected standard output. Come to think of it, let's not overwrite that file. Similarly if you want to append to something that doesn't already exist: 75 D% echo appended data >> newdata csh: Couldn't open 'newdata' as a redirected standard output. 76 D% echo appended data >>! newdata 77 D% cat newdata appended data 78 D% rm newdata Protection Attributes If a file has any of the special protection attributes, hidden, read-only or system, set, you cannot overwrite it by redirecting i/o to it. Even when you type ``!'', you still can't. Before you can redirect to it, you must clear all these attribute bits. 79 D% ls -l zork -SHAR Feb 23 13:16 0 zork 80 D% echo new zork data >! zork csh: Couldn't open 'zork' as a redirected standard output. 81 D% chmod -R zork 82 D% echo new zork data >! zork csh: Couldn't open 'zork' as a redirected standard output. 83 D% chmod -SH zork 84 D% ls -l zork ---A- Feb 23 13:16 0 zork 85 D% echo new zork data > zork 86 D% _ Page 56 User Guide Stdout and Stderr Redirecting both stdout and stderr together is done by adding an ampersand. For example, using echo's ``-2'' option to deliberately write to stderr and parentheses for a simple grouping: 86 D% (echo -2 error; echo standard) > zork error 87 D% cat zork standard 88 D% (echo -2 error; echo standard) >& zork 89 D% cat zork error standard 90 D% _ Separately redirecting stderr and stdout to different files is a little tricky: first you redirect them both, then redirect stdout by itself. Here's an example running the C compiler with stdout to log and stderr going to errors. 90 D% cl hello.c >& errors > log You can type as many i/o redirections in a row as you like. The shell evaluates them one after another. If you redirect to a new file, then redirect to something else, the effect is just like touch'ing the file. Pipes Pipes are a way of connecting a series of activities together so that the output of one is read as input to the next. Each of the activities runs asynchronously and concurrently with the others. Data is passed completely in memory and is very fast. The syntax is similar to i/o redirection in its use of the ``&'' character. To pipe just stdout, use ``|'' by itself: 91 D% ls -L | more To pipe both stdout and stderr together, use ``|&'': 92 D% cl hello\hello.c |& more The leftmost part of the pipeline is evaluated directly by the shell's current thread. The successive right parts are evaluated by child threads. (This is so that piping a command that lists status information on Page 57 User Guide the current thread through a filter like more operates sensibly.) Each part of the pipeline can be an arbitrarily complex statement, perhaps even run as a separate OS/2 screen group or in a separate NT window. Pipes are much faster and more responsive than with vanilla OS/2 or NT due to improved buffering and scheduling technology. A long pipeline finishes much faster. Also, when you type ^C to interrupt, it comes back immediately without a lot of nuisance messages. Page 58 User Guide Command Substitution A particularly novel way of piping statements together is to use the output of one as command line arguments of another. This is called command substitution and you indicate it by typing backquotes, `...`, around a command. 93 D% ls +a . hello zork .. memos 94 D% echo `ls +a` . hello zork .. memos 95 D% _ When command substitution is done, all the extra ``white space'' (space characters, tabs and newlines) is squeezed out. Also, any ANSI escape sequences that might have turned on highlighting or color, etc., are deleted. You just get the list of words the backquoted command wrote to stdout. In this example, the order of the files is a bit scrambled when the line ends are removed; the -1 (numeric one) single column option can fix this. (Try it again using ls +a1 inside the backquotes.) Command substitution is especially useful anywhere you need to give a list of filenames as arguments to a command. Here's an example using ls to give a detailed listing of the two more filters, the old and the new: 95 D% whereis more c:\hamilton\more.exe c:\os2\more.com 96 D% ls -l `whereis more` ---A- Mar 20 8:00 20123 c:\hamilton\more.exe ---A- Oct 26 12:00 31658 c:\os2\more.com (Our more is ``less filling and tastes better.'') The string inside the backquotes is passed directly to a child thread for interpretation. If there are any variable substitutions inside the backquotes, they're done by the child, not the parent. This lets you easily embed for loops and other programming constructs into the command substitution. Inside backquotes, only the backquote character needs to be escaped to avoid having it processed by the parent thread. Inline Data Page 59 User Guide A novel variation on i/o redirection is inline data, also called ``here'' documents: literal text you want the shell to feed a command as stdin. Here's an example: Page 60 User Guide 97 D% cat <<eof 98 D? (this is the inline data) 99 D? eof (this is the inline data) 100 D% _ The ``<<'' operator is followed by a string the shell is asked to look for to mark the end of the inline data. The end-of-data string can be virtually anything you like, including wildcard characters, dollar signs, etc.; their normal meaning is turned off and they're treated as ordinary literal characters. Only quote or escape characters have any special meaning, which is to turn off substitutions in the inline text (as we'll discuss in a moment). Continuation lines as the shell collects the inline data get a different prompt, controlled by the prompt2 variable. Once the data has been collected in memory, it's written through a pipe to the command. One very convenient use of inline data is when you want to quickly search for any one of a number of important words in a large library. E.g., to scan for some specific strings in a set of C files: 100 D% fgrep -ns <<xxx ~\sh\*.c 101 D? DosOpen 102 D? DosClose 103 D? DosRead 104 D? DosWrite 105 D? xxx : search results In situations where the inline data is being created inside a larger structure, the data is assumed to start on the first line following a break between statements. For example, inside a for loop: 106 D% for i = 1 to 3 do 107 D? cat <<eof; echo i = $i 108 D? (this is the inline data) 109 D? eof 110 D? end (this is the inline data) i = 1 (this is the inline data) i = 2 (this is the inline data) i = 3 If you want to put several inline i/o redirections on the same line, type the associated inline data sections, each with its own terminating string, in the same left- to-right order in which they appeared. Page 61 User Guide So far, we've just shown examples involving static text. But it's also possible to ask the shell to do command and variable substitutions on the inline text: 111 D% cat << *** 112 D? The ^$home directory is $home. 113 D? Today's date is `date`. 114 D? *** The $home directory is d:\doug Today's date is Wed Mar 17 1993 14:40:51.12. 115 D% _ Notice that although substitutions and escape characters inside the here document are processed, quotes (both single and double) are not. [The C shell implements here documents by spawning a child thread to do any substitutions and write the results into a pipe feeding the current thread as it continues to evaluate the statement. If the here document contains references to shared variables, they'll be evaluated by that other thread. And unless they're local variables, the values will not be snapshotted when the here document thread is created. If the current thread (or any other thread) continues to make changes to a variable after the here document thread is spawned but before it evaluates the variable, the here document will contain the new, not the old value.] Command and variable substitution and escape processing inside a here document is turned off if any part of the end-of-data string following the << is quoted (with single, double or backquotes) or escaped: 115 D% cat <<^*** 116 D? The ^$home directory is $home. 117 D? Today's date is `date`. 118 D? *** The ^$home directory is $home Today's date is `date`. 119 D% _ Inline Data in Scripts Inline data can be especially useful if you're writing a script file or passing commands to the shell through a pipe. In either of these cases, the low-level DosReads to the OS/2 kernel (or WriteFiles to the NT kernel) cannot be depended on to stop at the end of a line because pipes and files are considered block-oriented rather than line-oriented like the keyboard. If too many characters are read, there's no simple way to back up. Page 62 User Guide For this reason, it's not realistic to write a script where a child process is supposed to inherit stdin pointed into the script file. In a script file, this is not reliable: Page 63 User Guide : : csh echo hello exit : : The file descriptor the child process inherits will likely not be pointing at the ``echo hello''; when it exits, the parent will likely not find it pointed just past the ``exit''. This type of script should be written as: : : csh <<eof echo hello exit eof : : Page 64 User Guide Page 65 User Guide The History Mechanism History The history mechanism lets you recall and rerun earlier commands. To see what it's remembered, use the history command or its usual alias h, which might show you something like the following: 119 D% history 12 108 (this is the inline data) 109 eof 110 end 111 cat << *** 112 The ^$home directory is $home. 113 Today's date is `date`. 114 *** 115 cat << ^*** 116 The ^$home directory is $home. 117 Today's date is `date`. 118 *** 119 history 12 120 D% _ The history list won't be quite what you typed: it'll be broken into separate words wherever one of the special tokens, &, |, ;, >, <, (, ), &&, ||, >> or <<, occurs. Only inline data escapes being broken up into words this way. Each command may be thought of as an array of words, indexed from 0.+ To reuse the text or maybe just a few words from a previous command, you type an exclamation point, ``!'', followed by a few characters to identify what you want to reuse. You can do this anywhere and whatever you select is just stuffed back on the command line to be interpreted as whatever the context suggests. For convenience, the exclamation point is not treated as a history reference if it's followed by white space (a space, tab or newline) or by ``='', ``~'' or ``(''. Retrieving a Whole Command Line ____________________ + Array indices always start with zero. Page 66 User Guide There several ways of picking up a whole command line. You already know how to do it interactively with arrow keys and command completion. You can also use a shorthand notation that can be more convenient if you want to do something a bit more complex. The simplest shorthand is ``!!'', which picks up the text of the immediately preceding command: 120 D% echo !! echo history 12 history 12 121 D% !! echo history 12 history 12 122 D% _ The shell first echoes your command showing the effects of the substitutions and then runs it. The other quick ways of referring to a whole command line from history are by the command number, 122 D% !96 ls -l whereis more` ---A- Nov 28 16:57 24743 c:\os2\bin\more.exe ---A- Oct 21 1987 48354 c:\os2\cmds\more.com relative to the immediately preceding command+, 123 D% echo one one 124 D% echo two two 125 D% echo three three 126 D% !-1 echo two two 127 D% _ or by mentioning some of the text to look for. A question mark after the exclamation point means you'll accept the match anywhere on the line; otherwise it has to be at the start. 128 D% !h history 12 116 The ^$home directory is $home. ____________________ + In this context, the history list can be thought of as an array starting with the zeroth element being the immediately preceding command line. The negative index captures the notion of counting backwards in time and differentiates the syntax from references by command number. See also the bsdhistory variable. Page 67 User Guide 117 Today's date is `date`. 118 *** 119 history 12 120 echo history 12 121 echo history 12 122 ls -l `whereis more` 123 echo one 124 echo two 125 echo three 126 echo two 127 history 12 A search string ends at the first word boundary. This is so it's convenient to type additional text following without having it be confused as part of the search string. For example: 128 D% !?one;!?two;!?thr echo one ; echo two ; echo three one two three 129 D% _ Retrieving Individual Words To pick off individual words of the immediately preceding command, there's some convenient shorthand. ``!*'' gets all the argument words: 129 D% echo now is the time now is the time 130 D% echo Finally, !* to begin echo Finally, now is the time to begin Finally, now is the time to begin 131 D% _ ``!$'' gets just the last word: 131 D% echo the last word was !$. echo the last word was begin. the last word was begin. 132 D% _ and ``!^'' gets just the first argument word: 132 D% echo ===!^=== time is here echo ===the=== time is here ===the=== time is here 133 D% _ Page 68 User Guide Notice that a history substitution can be smashed right up against other literal text. In the chapter on editing, additional facilities for selecting individual words or doing a search/replace will be introduced. History Short-Form Recognizing how frequently one would like to make a simple change to the immediately preceding command to correct a typo, the history mechanism provides a short form for just that purpose. ``%'' typed as the first character on the command line indicates that a search/replace pair follows: 133 D% echo hello world hello world 134 D% %world%friends% echo hello friends hello friends Typing ``%%'' matches the beginning of the line: 135 D% %%echo % echo echo hello friends echo hello friends It's also possible to refer to the search string in the replacement string by using an ampersand. (This example also illustrates that the trailing ``%'' isn't required unless you want to explicitly mark the end of the replacement.) 136 D% %friends%family, & and neighbors echo echo hello family, friends and neighbors echo hello family, friends and neighbors 137 D% _ Obviously, that raises the question: how do you put a literal ampersand in the replacement? Simple. Just quote it with ``^'', the shell escape character. 137 D% %and%^& echo hello family, friends & neighbors hello family, friends & neighbors 138 D% _ Page 69 User Guide Variables As with any conventional programming language, the shell provides a facility for storing values in variables. Environmental Variables Some of the variables are part of the environment, passed along to any child process or screen group. Many of the environment variables will have been created just this way, e.g., set to a value passed along when you start the C shell from Group Main (on OS/2) or the Program Manager (on NT). To list those currently defined, use the setenv command. (If you're using Windows NT, mentally edit this example to imagine it says nt everywhere you see os2.) 138 D% setenv COMSPEC c:\os2\cmd.exe COLORS white on blue DPATH c:\os2;c:\os2\system;c:\os2\install;c:\; HOME d:\doug INCLUDE c:\os2\include LIB c:\os2\lib PATH .;c:\os2\bin;c:\os2\cmds;c:\os2 PROMPT $iOS/2 $n$g PROMPT1 $@ $CDISK% PROMPT2 $@ $CDISK? SHELL c:\os2\bin\csh.exe TABS 3 TMP e:\tmp Variable names are case-sensitive on OS/2 but case- insensitive on NT. They can be of arbitrary length. A name must start with an upper- or lower-case alphabetic character or underscore (``_'') or at-sign (``@''); remaining characters may any of these or decimal digits. Many of the environmental variables have specific meanings. For example, the PATH variable tells where to look for executable files, etc. Details describing the meaning of each variable are given in the language reference section. The setenv command can also be used to create a new environmental variable or alter or display the value of an existing one: Page 70 User Guide 139 D% setenv zork = this is the zork variable 140 D% setenv zork zork this is the zork variable 141 D% _ If the list of words being assigned to the variable includes any special tokens, it's often useful to use the parenthesized variant of setenv. In this example, the ``>'' would have been confused as an i/o redirection if it weren't inside parenthesis. Notice that the parenthesis are stripped off before the assignment is made. 141 D% setenv greatest = (At Berkeley, they say 4.3 > V) 142 D% setenv greatest greatest At Berkeley, they say 4.3 > V Even though the special meaning is lost, text inside the parenthesis is still broken down into words, as shown in this example: 143 D% setenv pdirs = (.;c:\os2\bin;c:\os2\cmds;c:\os2;) 144 D% setenv pdirs pdirs . ; c:\os2\bin ; c:\os2\cmds ; c:\os2 (To avoid having the text broken up into words, use single or double quotes around the string instead.) Set Variables Set variables do not get passed to a child process but are shared among all threads. To get a list of those currently defined, use the set command: 145 D% set CDISK D argv cdhome 0 cdisk d : : path . c:\os2\bin c:\os2\cmds c:\os2 precision 6 : : Some of the set variables are linked to the environmental variables: you change one, and the other changes too. For example, path contains the same Page 71 User Guide information as PATH but, because it's been parsed into individual words, it's often a bit more useful. On NT, this linkage can pose a bit of a problem. Since the convention on NT is that environmental variables are supposed to be case-insensitive, there clearly is a conflict between, for example, the PATH environmental and path set variables. The C shell resolves this by making the set, unset and @ statements case-sensitive (so you can still create set variables that differ from environmental variables only by case) but the setenv and unsetenv and $var and other variable references first try case-sensitive, then case insensitive variable lookups. Many of the set variables are pre-defined by the shell to control various aspects of how errors are handled, etc. In some cases, each thread maintains its own copy. For example, it wouldn't do to insist that all threads must use the same value for the cwd (current working directory) variable! The rest of the variables, including any defined by the user, are shared among all threads: if one thread changes a value, all the other threads see the change immediately. As we'll see later, this has some implications when spawning background activities. In other respects, set works just like setenv: 146 D% set privatezork = this is the private zork variable 147 D% set privatezork privatezork this is the private zork variable 148 D% _ Once a variable has been created as either a set or an environmental variable, it stays that way: to change it from set to environmental, you must first unset (unsetenv) it, then redefine it. Local Variables We just mentioned that not all the pre-defined set variables are shared. Individual threads get their own private copies of some because to do otherwise wouldn't be sensible. Sometimes you need the same sort of control over the variables you create. You don't want to share a variable with other threads or even with commands outside a very narrow context. You accomplish this making the variable local, which means it's hidden from outer control blocks or other Page 72 User Guide threads. Local variables are really important, as we'll see later, for recursive procedures or for procedures you want to use from multiple threads. To define a variable as local, use the local statement, which accepts a list, separated with commas, of all the variable names you want to be local. When a new local variable is created, its initial value is always null (zero words), even if there was a previous definition. Here you can see how the variable i is redefined inside the nested statements but once you exit from the nest, the old value of i is again visible: 148 D% set i = hello world 149 D% echo $i hello world 150 D% (local i; echo $i; set i = how are you; echo $i) how are you 151 D% echo $i hello world When you spawn a child thread, e.g., as a background activity or as the second or following stage of a pipeline, it gets copies of all your local variables, snapshotted at the time it's spawned. If either the parent or the child later changes to the value of any those local variables, they affect only it's own copy. Page 73 User Guide Variable Substitutions The simplest way to use a variable is in a simple substitution, where a dollar sign is used to indicate that a variable name follows. (Similar to using a ``%'' in cmd.exe.) The value is substituted in and the statement is evaluated. 152 D% echo $HOME d:\doug Text surrounding the variable reference is generally just pasted around the value that's substituted in: 153 D% echo My home directory is ---$HOME--- My home directory is ---d:\doug--- If the surrounding text would be confused as part of the variable name, it's necessary to insulate the variable reference with braces. For example: 154 D% echo ${HOME}XXX d:\dougXXX nonovar If you try to reference a variable, procedure or an alias and it doesn't exist, it's considered an error unless you set the nonovar variable to indicate how you want the situation treated. 155 D% echo $nonesuch csh: The variable 'nonesuch' is not defined. To suppress this error, set nonovar = 1 (pass through) or 2 (discard). 156 D% set nonovar = 1 157 D% !e echo $nonesuch $nonesuch 158 D% set nonovar = 2 159 D% !e echo $nonesuch 160 D% set nonovar = 0 How Variables are Stored Each variable is kept internally as a list (an array) of objects. An individual object can be a (possibly null) character string, a 32-bit integer or a 64-bit Page 74 User Guide floating point value. Generally speaking, it's not necessary to worry too much about how a specific object is represented, though, since the shell automatically does any necessary conversions to allow a value to be used sensibly in any given context. Notice, however, that even though the value of an environmental variable may be a list, it is always rendered as a simple character string when it's passed to a child process. Here's an example using the ``$#'' notation to ask how many words are in a variable's value: 161 D% echo $zork this is the zork variable 162 D% echo $#zork 5 163 D% csh Hamilton C shell(tm) Release 2.1 Copyright (c) 1988-1993 by Hamilton Laboratories. All rights reserved. 1 D% echo $zork this is the zork variable 2 D% echo $#zork 1 3 D% exit 164 D% _ In this example, zork holds five words: ``this,'' ``is,'' ``the,'' ``zork,'' and ``variable.'' But when we start up a new child process running the shell, the child process sees zork as holding only a single word: ``this is the zork variable''. Here's another example where we assign a floating point value to an environmental variable. In the current process, the exact binary floating representation is used. When it's passed to a child process, the value is first converted to a character string, losing some of the precision. This example also introduces the calc statement which evaluates an expression and prints the value. In an expression, a variable name is recognized even without a ``$'' to introduce it; in fact, that's the preferable way to do it. If you use a ``$''-style variable substitution, the shell pastes in a character- string representation, again losing precision. Also, the full range of C language expression operators is available. 164 D% setenv envVar = 0 165 D% calc ++envVar 1 166 D% calc envVar /= 7 0.142857 167 D% calc envVar*7 Page 75 User Guide 1.000000 168 D% csh <<eof 169 D? calc envVar*7 170 D? exit 171 D? eof Hamilton C shell(tm) Release 2.1 Copyright (c) 1988-1993 by Hamilton Laboratories. All rights reserved. 0.999999 172 D% calc $envVar*7 0.999999 Arrays Variables can hold a list of values indexed as an array. As with the C language, arrays are indexed, counting from zero, with an expression inside ``[...]'' brackets. The expression can be arbitrarily complex, but it must evaluate to an exact integer value. The next example shows how a floating point value can be used, but if it's not precisely an integer, an error results. The precision variable controls the number of digits past the decimal point used when displaying a floating point value; the maximum is 17 digits. 173 D% set x = now is the time for all good men 174 D% calc x[5.000000] all 175 D% calc 2**500 3.27339061e+150 176 D% calc y = log2(!$)/100 calc y = log2 ( 2**500 ) /100 5.000000 177 D% calc x[y] csh: Couldn't evaluate the index to the variable 'x'. 178 D% set precision = 30 179 D% calc precision 17 180 D% calc y 5.00000000000000100 181 D% calc x[round(y)] all An array cannot be ``sparse;'' i.e., before you can create an element 5, element 4 must exist and so on. But it's perfectly legal to keep adding new elements onto the end of array as long as the new element is the zeroth element or only one past whatever's currently the last element. Here's an example using a for loop. The @ statement is like calc except it doesn't print anything. Page 76 User Guide 182 D% unset x 183 D% for i = 0 to 4 do 184 D? @ x[i] = 2*i 185 D? end 186 D% echo $x 0 2 4 6 8 nullwords When you index an array, if the element you specify doesn't exist, that's normally considered an error. For example, x contains 5 words; trying to reference a sixth fails: 187 D% calc x[5] csh: Illegal subscript in variable reference 'x[5]'. (To suppress this error, set nullwords = 1.) The nullwords variable is used to tell the shell that you'd like to ignore subscripting errors when you try to evaluate a variable reference. nullwords has no effect over subscripting errors when you try to set the value of a non-existent element. Here are some examples: 188 D% set nullwords = 1 189 D% echo -- "--->$x[999]<---" ---><--- 190 D% calc x[999] = "does not work" csh: Illegal subscript in variable reference 'x[999]'. The use of the ``--'' option and of double quotes was important: ``--'' told echo that it had reached the end of any options, allowing it to print something that began with a minus sign. The quotes were used, in the first case, to turn off recognition of redirection characters ``>'' and ``<'' but still get the variable substitution. The second time, it was to make the string, ``does not work'' a single word. (If you try leaving off the quotes or not using ``--,'' you'll see that the error messages are what you'd expect.) Page 77 User Guide Page 78 User Guide Wildcarding The notion of wildcarding is pretty simple: the user gives just a few characters describing the filename he's looking for and system fills in the rest. With ``vanilla'' OS/2 or NT, wildcarding is the responsibility of each application, based on the command-line arguments it's given. Typically, the application designer fulfills this by linking in a library routine which does a simple- minded half-hearted wildcarding. Hamilton C shell does the wildcarding before invoking the application. The shell's wildcarding includes five components: home directory expansion, wildcarding characters, ranges, alternation and indefinite directories. A powerful recursive match algorithm is employed to guarantee a sensible result no matter how complex the pattern. Home Directory Expansion The tilde character, ``~'', is recognized as shorthand for the home directory. In the simplest form, we can use it just by itself: 191 D? echo $home d:\doug 192 D% cd ~ 193 D% cd d:\doug There's also shorthand for children or siblings of the home directory: 194 D% cd ~\samples 195 D% cd d:\doug\samples 196 D% cd ~carol 197 D% cd d:\carol Wildcard Characters The wildcard characters, ``*'' and ``?'', provide shorthand for ``match any string'' and ``match any single character,'' respectively. Page 79 User Guide Suppose the home directory contained the following contents: 198 D% cd ~ 199 D% ls Page 80 User Guide bcs mandel sh ex.rc release.csh bix mba testcode icon.ico ring.ico channel.one online util login.csh snapshot.csh dial postscpt word mail startup.csh excel regressn backup.csh os2init.cmd vi.ini games resume brite.csh popup.txt icon samples class.txt prime.c The following example shows the use of ``?'' to match any single character. Wildcard results are always shown alphabetically in lower case. No distinction is made between directories and files. 200 D% echo ???? dial icon mail util word 201 D% echo b?? bcs bix The ``*'' can match zero or more arbitrary characters except ``:'' or ``\''; in contrast to DOS-style wildcarding, ``*'' can match ``.''. If there are ordinary characters in the pattern, they must also be matched. 202 D% echo *mp*e* samples Because the wildcarding is done before the command is invoked (without the command even being aware), wildcarding can even be done on a cd command: 203 D% cd !$ cd *mp*e* 204 D% cd d:\doug\samples Wildcarding is most emphatically not restricted to matches only against a single directory level. Here's an example that wildcards across all the subdirectories, looking for .c files that begin with ``a''. 205 D% cd .. 206 D% echo *\a*.c samples\args.c sh\allocate.c For a real surprise (that it works), try the following example. (You'll quickly appreciate why the result is not shown here.) Page 81 User Guide 207 D% echo * *\* *\*\* Ranges Ranges describe a set of characters, any one of which will be matched. It's specified as a list of acceptable characters inside ``[...]'' brackets. The range ``[be]'' means either ``b'' or ``e''; ``[b-e]'' is shorthand for any character in the sequence ``b'' through ``e''. Within the brackets, any number of hyphenated sequences and single characters can pasted one after the other in any order. For example, ``[a-cu-zgkmp]'' is a perfectly legal range. 208 D% echo [be]* backup.csh bcs bix brite.csh ex.rc excel 209 D% echo [b-e]* backup.csh bcs bix brite.csh channel.one crash.csh dial ex.rc excel An exclusion range is written as a set of characters inside the brackets that starts with a circumflex. It'll match any single character not in the range. 210 D% echo [^a-t]* util vi.ini word Alternation Alternation, specified with ``{...}'' braces, is a shorthand way of specifying that all the combinations of frontparts and backparts should be generated. There isn't any requirement that the filenames constructed actually exist. 211 D% echo {zork,gadzooks}.csh zork.csh gadzooks.csh 212 D% echo {a,b}{c,d}{e,f} ace acf ade adf bce bcf bde bdf Alternation can be combined arbitrarily with the other wildcard constructs: 213 D% echo {[bc],*r}*i* bix brite.csh brite.csh ring.ico Indefinite Directories Page 82 User Guide The ellipsis, ``...'', is an indefinite definite directory wildcard. It'll match zero or more arbitrary directory levels -- whatever it takes to make the rest of the wildcard match. To be recognized as a wildcard, the context must indicate it's really a filename, i.e., it must be preceded by ``\'', ``/'', ``~'' or ``:'' or followed by ``\'' or ``/''. For example, to find all the .inf files anywhere on the C: drive, one might type: 214 D% ls c:\...\*.inf c:\os2\book\cmdref.inf As with all the wildcard constructs, the indefinite directory construct can be used completely arbitrarily. It can even be used several times in the same wildcard. But do notice if you do that, there is a possibility of getting the same file listed more than once: 215 D% ls f:\...\a*\...\money* f:\os2\aldus\art\moneycht.eps f:\os2\aldus\art\moneycht.eps This can happen if there's more than one possible way to match the same pathname. In this example, the ``a*'' part could matched either ``aldus'' or ``art'' with the first ``...'' matching either ``os2\aldus'' or ``os2'' and the second ``...'' matching either ``art'' or just zero levels. Match Failures When you specify a sequence of wildcard patterns and none of them match, it's normally treated as an error. In this example, the first command causes an error because there's no file or directory name with a ``z'' in it. The second command executes without error because, out of the sequence of patterns, there's at least one match. 216 D% echo *z* csh: Wildcarding failed to produce any matches. To suppress this error, set nonomatch = 1 (pass through) or 2 (discard). 217 D% echo *z* sa* samples In this context, the fact that alternation caused something to be generated is not the same as a match. In the next example, ``{zork,gadzooks,*z*}.csh'' is the same as ``zork.csh gadzooks.csh *z*.csh''; only the last element involves any matching, and it fails. Page 83 User Guide 218 D% echo {zork,gadzooks,*z*}.csh csh: Wildcarding failed to produce any matches. To suppress this error, set nonomatch = 1 (pass through) or 2 (discard). The nonomatch variable lets you control how a wildcard failure is treated. It works just the way nonovar works when you reference to a non-existent variable. 219 D% set nonomatch = 1 220 D% echo *z* *z* 221 D% !s:s/1/2/ set nonomatch = 2 222 D% !e echo *z* 223 D% !s:s/2/0/ set nonomatch = 0 224 D% !e echo *z* csh: Wildcarding failed to produce any matches. To suppress this error, set nonomatch = 1 (pass through) or 2 (discard). Page 84 User Guide Caution: The copy, xcopy, rename and del commands Hamilton C shell expands out wildcards before it invokes the application you name. This is not what the copy and xcopy commands expect! Suppose there are two files, file.a and file.b on your diskette a:, that you wanted to copy to your current drive. Under cmd.exe, it would be natural to type: [D:\DOUG] xcopy.exe a:*.* Source files are being read... A:FILE.A A:FILE.B 2 file(s) copied. The destination is implicit. xcopy understands the wildcarding to mean ``copy everything on drive a: to the current disk and directory.'' That is not what would happen under the C shell! Because the wildcard would be expanded first, it would act instead as if you had typed: [D:\DOUG] xcopy.exe a:file.a a:file.b Source files are being read... A:FILE.A 1 file(s) copied. Do you see what happens? If wildcarding is done first, the xcopy command sees just the two filenames and figures you mean to copy one right over the other. file.b is lost! For this reason, the normal startup.csh file contains some carefully constructed aliases and procedures to intercept the copy, xcopy, rename and del commands: proc safecopy(files) cmd /c copy $files; @ nowild = s; unlocal s end alias copy (local s; @ s = nowild; @ nowild = 1; safecopy) proc safexcopy(files) xcopy.exe $files; @ nowild = s; unlocal s end alias xcopy (local s; @ s = nowild; @ nowild = 1; safexcopy) proc saferename(files) cmd /c rename $files; @ nowild = s; unlocal s end alias rename (local s; @ s = nowild; @ nowild = 1; Page 85 User Guide saferename) alias ren rename Page 86 User Guide proc safedel(files) cmd /c del $files; @ nowild = s; unlocal s end alias del (local s; @ s = nowild; @ nowild = 1; safedel) alias erase del The way this works by saving the current value of nowild (which tells whether wildcarding is should be done), turning off wildcarding, invoking the copy/xcopy/rename/del command, then restoring the wildcarding state. s is a temporary variable that gets discarded after its been used. Be sure to always invoke copy, xcopy rename and del via these aliases. If you encounter other applications that really must do their own wildcarding, use this same technique with them. Page 87 User Guide Editing Often, the text returned by a history, variable or command substitution isn't quite what you want. For example, you may want to select only certain words, do a search/replace, or manipulate a filename that's been returned. The editing facilities provide these capabilities. The examples in this chapter show a sampling of various combinations of editing commands and types of substitutions. There simply isn't room to show all the possibilities nor is there really a need to: with two exceptions (``:%''and ``:p''), any editing command can be applied against any substitution type or against the result of another editing command. Word Selections Editing modifiers begin with a colon, ``:'', followed by an editing command. You can select words either by number or symbolically: first, last, all, etc. Here are examples of the ``:*'', ``:$'' and ``:^'' modifiers to select all, last, and first argument words, respectively. Notice that any number of editing modifiers may strung together. For example, ``:*:^'' means the first argument word (word 1) of the sequence formed of all the original argument words: i.e., word 2. 225 D% echo Finally, now is the time Finally, now is the time 226 D% echo !!:$ time 227 D% echo !?Fin:*:^ echo now now It is also possible to select words by indexing through the array associated with a given substitution. The words are counted from zero. 228 D% echo `echo now is the time`:2 the Ranges of words can also be specified with a hyphen between the beginning and ending word indices. In this context, the minus sign indicates a range, not subtraction. Page 88 User Guide 229 D% set x = now is the time for all good men 230 D% echo $x:1-5 is the time for all When the operand is a ``!?''-style history substitution, there's a special operator, ``:%'', for selecting the particular word that triggered the match: 231 D% echo !?Fin:% echo Finally Finally Each of the three symbolic word selectors, ``^'', ``$'' and ``%'', can be used anywhere a decimal word number would be acceptable. For example: 232 D% echo !?time:%-$ echo time for all good men time for all good men Search/Replace Operations A search/replace operation looks for and replaces a simple character string. (For those familiar with such things, it does not use regular expressions.) If the search string isn't given, the one used last time is used again. If the replace string contains an ampersand, ``&'', that isn't escaped with the circumflex, it's expanded into the search string. Here are a few examples. Notice that putting a ``g'' at the start of an operation makes it ``global.'' 233 D% echo !?now:%-$:s/o/O/ echo nOw is the time for all good men nOw is the time for all good men 234 D% !!:gs/t/T/ echo nOw is The Time for all good men nOw is The Time for all good men 235 D% !!:s/nOw is/& really/ echo nOw is The Time for all good men nOw is really The Time for all good men Pathname Editing Another set of operators allows filenames to be easily manipulated. As with the search/replace operator, pathname editing is normally applied to only the first operand word; if you want the operation performed on all the words, you must make it global. In this example, the Page 89 User Guide ``:h'' (head) operator is used, which returns the name of the directory containing the given file. 236 D% echo *\a*.c samples\args.c sh\allocate.c 237 D% set dotc = !$ set dotc = *\a*.c 238 D% echo $dotc samples\args.c sh\allocate.c 239 D% echo $dotc:h samples sh\allocate.c 240 D% echo $dotc:gh samples sh Specialized Operations Specialized operations are provided for scanning a character string and breaking it up into words and applying quotes around each word. The ``:x'' operator for breaking up a string into words is particularly useful for parsing text read with the getline pseudo-variable, which always returns the line read as a single character string: 241 D% @ data = $< (I typed -->this<-- in) 242 D% echo $#data $data 1 (I typed -->this<-- in) 243 D% set data = $data:x 244 D% echo $#data $data 10 ( I typed -- > this < -- in ) The ``:q'' operator pastes single quote marks around every word in the operand list. As we'll see in the chapter on quoting, this prevents any further wildcard, variable or command substitutions from being done. 245 D% echo sa?pl?s *\a*.c samples samples\args.c sh\allocate.c 246 D% echo !*:q echo 'sa?pl?s' '*\a*.c' sa?pl?s *\a*.c History Edits For history substitutions, the ``:p'' operator can be used to cause the result of the history substitution to be echoed and entered into the history list but for the command not to be executed. This is helpful when you're Page 90 User Guide trying a complicated edit and not sure if the result is going to be what you want. 247 D% !?Fin:p echo Finally 248 D% !! echo Finally Finally 249 D% _ Page 91 User Guide Page 92 User Guide Quoting The shell has several quoting mechanisms for marking a section of a command for special processing. One of them, command substitution, which used the `...` syntax, was already discussed in the chapter on i/o redirection; that discussion won't be repeated here. The other quoting mechanisms focus more simply on the problem of overriding the special meanings that certain characters have. Double Quotes Double quotes are of use when you want to pass a character string containing a space or other word separator to an application. Normally, if you called a C program, it would see these words as separate argv entries instead a single character string; double quotes prevents this breakup into words. We can demonstrate this using the simple myecho program in the samples directory which prints out the argv list it receives with single quotes around each entry: 249 D% cd ~\samples 250 D% myecho hello world 'myecho' 'hello' 'world' arg length = 19 characters 251 D% myecho "hello world" 'myecho' 'hello world' arg length = 19 characters Double quotes also turn off the special meaning of the various wildcard characters and the single quote: 252 D% echo "* isn't a wildcard character inside quotes" * isn't a wildcard character inside quotes 253 D% echo "~" ~ 254 D% _ Command, history and variable substitutions inside double quotes are still done: 254 D% echo "*** The home directory is $home ***" *** The home directory is d:\doug *** 255 D% echo "`echo ~`" Page 93 User Guide d:\doug 256 D% echo "myecho.c is `wc -l < myecho.c` lines long" myecho.c is 24 lines long 257 D% echo "!?samples" echo "cd ~\samples" cd ~\samples Single Quotes Single quotes are a little more brute force to turn off special meanings. Wildcards, variables and command substitutions are all treated as ordinary text. Only history references are recognized inside single quotes. 258 D% echo '*' * 259 D% echo '$cwd' $cwd 260 D% echo '`echo hello`" `echo hello` 261 D% echo '!?samples' echo 'echo "cd ~\samples"' echo "cd ~\samples" 262 D% _ It is not necessary to quote an entire word. It's possible (and often useful) to selectively quote just as much as desired. The quoting characters are processed out just before invoking the command. Example: 263 D% echo 'no'w is "t"h'e' `echo time` now is the time Shell Escape Character The shell escape character is normally the circumflex+, ``^''. It has two uses: preceding any of the special characters, it turns off that special meaning. When followed by an alphabetic character or hex or octal number, it can be used to enter binary data or characters that couldn't easily be typed. To get a ____________________ + The circumflex was chosen as the default shell escape character to be consistent with OS/2 conventions. Choosing the Unix backslash instead would have conflicted badly with OS/2 filename conventions. Nonetheless, the escapesym variable does allow the adventuresome to make a different choice. Page 94 User Guide literal escape character, type two escapes in a row. These specific escape sequences have special meaning: ^a Audible Alert (Bell) ^r Carriage Return ^b BackSpace ^t Tab ^f Form Feed ^v Vertical Tab ^n NewLine ^^ Single escapesym At the very end of a line, the escape has a special meaning: the next line is a continuation line. Inside a quoted string, the ``^''-newline combination will be replaced with a simple newline; anywhere else, the combination is just turned into a space. The other special case is when it immediately follows ``[''. Since ``[^...]'' is a wildcard exclusion range, the ``^'' in this case is treated as a literal character so you won't have to type two of them in a row. Escape characters work even inside single or double quotes. 263 D% echo now ^ is the time now is the time 264 D% echo "now ^ is the time" now is the time 265 D% _ Quoting just part of a Word It's possible to combine the quoting mechanisms or use them on just the part of a string you want quoted. For example, 265 D% echo '$cwd='$cwd $cwd=d:\doug Here's another example, searching through a series of .csh files, looking for those that are self-loading procedures. For example, we can spot that whereis.csh is self-loading because it contains a line like this: whereis $argv To look for occurrences of this sort, we might loop through a list of .csh files, grep'ing each for the filename (minus the directory and .csh extension) followed by white space followed by ``$argv'': Page 95 User Guide 266 D% foreach i (~\samples\*.csh) 267 D? grep $i:b'[ ^t]*$argv' $i 268 D? end bits $argv bumpdate $argv caldate $argv calendar $argv : Notice how the ``$i:b'' part is outside the quotes so that the filename can be substituted in and edited to strip off the directory and extension. Conversely, the ``[ ^t]*'' and ``$argv'' portions are inside the quotes to avoid having them confused as a wildcard or variable substitution, respectively. Wildcarding with Special Characters If you'd like to wildcard filenames that have literal $'s, ['s, quotes or spaces (under HPFS) or other special characters, you'll have to quote or escape the special characters to turn off their special meanings. For example, 269 D% ls g:\tmp $abc [hello this name has spaces 270 D% ls '$'* $abc 271 D% ls *^ * this name has spaces Page 96 User Guide Expressions As we've seen, sometimes a character like ``*'' means wildcard and sometimes it means multiply. The meaning of what you type is determined by the context. The shell makes a distinction between words, used as arguments to a command versus an expression context. In general, expressions are expected wherever the context would seem to suggest that it would be more natural to think of calculating a value as opposed to using wildcarding to produce a list of filenames. Expressions The shell's expression grammar is based on that of the C language and provides the full range of arithmetic, logical, bit, indexing and relation-testing and assignment operators. In addition, there are file system tests and pattern matching string compares. To use the shell as simple calculator, use the calc statement. This example shows a call to the square root routine, one of the built-in procedures. 272 D% calc sqrt(2*pi) 2.506628 which writes its result to stdout. If you want to do the calculation silently, use the ``@'' variant:+ 273 D% @ r = 12 274 D% @ area = pi * r**2 275 D% calc area 452.389345 In addition to the calc and @ statements, other examples where an expression is expected include a variable index inside ``[...]'' brackets, in a procedure argument list and, as we'll see, a number of the structured programming constructs such as the for statement. Expression Parsing ____________________ + The choice of @ is a pun: ``at-sign-ment'' statement. Page 97 User Guide All commands are first broken down into words. A word is anything separated by a space or a tab or one of the following special strings: & ,|, ;, >, <, (, ), &&, ||, >> or <<. After a command line has already been broken up into words, if the context is an expression, it's further broken up into tokens. A token is a variable or procedure name, a character or numeric literal, or one of the expression operators. Spacing between tokens is more-or-less arbitrary: for example, there's certainly no need to put spaces around an arithmetic operator to separate it from a variable name beside it. Tokens are separated by any of these characters or character pairs: &, |, ^, +, -, *, /, %, //, =, !, ~, <, >, (, ), [, ], ,, :, ;, -A, -D, -H, -S, -d, -e, -f, -o, -w, -x, -z, ++, --, **, <<, >>, ==, !=, =~, !~, +=, -=, *=, /=, %=, //=, ^= and **=. The <=, >=, <<=, >>=, &=, and |= are always broken up into separate words before expression parsing begins; for consistency, the parser will accept any of ``op='' assignment operators with a space between the ``op'' and ``='' parts.+ Since the shell knows that any names it encounters in an expression must refer to variables or procedures it's not necessary to use a dollar sign to introduce a variable name. In fact, you'll find that performance is actually a bit better if you do not use a dollar sign. The reason is because a $-style variable substitution is evaluated by converting the internal value of the variable to a string and pasting that into the expression where quite often the next step is just to convert it right back again into the integer or floating point value it started out as. Also, if floating point is involved, you may notice some loss of precision. (But don't misunderstand, it is still perfectly legal to use $-style variable and other substitutions in an expression.) Character literals must appear inside single or double quotes. Numeric literals can be entered in decimal, octal or hex. Octal numbers can contain only the digits 0 through 7 and must begin with 0. Hex numbers must start with ``0x'' and contain only 0 through f. (Either upper or lower case is acceptable.) Expression Operators ____________________ + The grammar is not perfectly lr(1): proper recognition of the file system tests and the assignment operator requires that parsing decisions in some places have to look ahead two tokens, not just one. Page 98 User Guide Expressions are evaluated according to the relative precedence of each operator in the expression. For example, multiplication is done before addition. The complete precedence hierarchy is shown in tabular form in the language reference. 276 D% calc 2 + 3*5 17 Some of the operators will be foreign, though we trust, not too difficult to use. The file system tests are unary operators. Each takes the name of a file or directory and tests it for existence, zero-length or some other interesting characteristic. Since the operand is a pathname, the parser temporarily shifts to word mode to read it because word mode is more natural for pathnames. The pathname can include wildcards and should not be enclosed in quotes. In the example that follows, ``-e'' tests for existence; ``-D'' tests whether the name is a directory. 277 D% cd ~\samples 278 D% ls args.c colors.csh factor.csh mcvisa.csh readme args.exe deltaday.csh finance.csh myecho.c ts.csh bits.csh dumpenv.c getprio.c myecho.exe viopaste.c bumpdate.csh dumpenv.exe getprio.exe newfiles.csh viopaste.exe caldate.csh duplicat.csh julian.csh rcode.c weekday.csh calendar.csh easter.csh makecpgm.csh rcode.exe 279 D% echo a*c args.c 280 D% calc -e a*c 1 281 D% calc -D !$ calc -D a*c 0 File System Tests The value returned from a file system test is always 1 or 0; there are no restrictions on how the value might be used in further calculations. 282 D% calc 1 + (!*) + (-e myecho.c) calc 1 + ( -D a*c ) + ( -e myecho.c ) 2 Page 99 User Guide Increment and Decrement Operators The unary incrementing and decrementing operators are ``++'' and ``--''. Pasting one in front of a variable name bumps the variable, then returns the value. Pasting one after the name bumps the variable but returns the prior state. 283 D% calc x = 1 1 284 D% calc ++x 2 285 D% calc x++ 2 286 D% calc x 3 287 D% calc --x 2 Bit Shifting The ``<<'' and ``>>'' bit shifting operators shift an integer value on the left by the number of bit positions given by the integer value on the right. Bits shifted off the end are lost; values shifted in are always 0. 288 D% calc x << 3 8 289 D% calc x >> 10 0 Bit Not Operation The unary ``~'' operator returns the bit-wise not of an integer operand. As this example shows, integers are 32-bit signed values. 290 D% calc ~5 -6 291 D% calc 0xfffffffa -6 292 D% calc ~!$ calc ~0xfffffffa 5 Logical Not Page 100 User Guide The unary ``!'' operator returns the logical not. If the operand is non-zero, 0 is returned, otherwise 1. In this example, the parentheses or space after the exclamation are deliberate to avoid having the expression confused as a history reference. 293 D% calc !(5.1) 0 294 D% calc ! 0 1 Exponentiation The ``**'' operator is for exponentiation. The left operand is raised to power of the right operand. 295 D% calc 2 ** 500 3.27339061e+150 Modulo and Integer Division The ``%'' operator is for modulo division and returns the remainder. 296 D% calc 22 % 7 1 A related ``//'' operator does integer division. Where the standard ``/'' operator might return a floating point result, ``//'' gives just the integer part of any division. 297 D% calc 8/3 2.666667 298 D% calc 8//3 2 Comparison Operators The ``=='' operator tests for equality; the single ``='' means assignment. The ``!='', ``<'', ``<='', ``>='', and ``>'' operators are all straight-forward tests of ``not equal,'' ``less than,'' ``less than or equal,'' etc. Comparisons of strings are as easy as of numbers. 299 D% calc x = 3 3 Page 101 User Guide 300 D% calc x == 5 0 301 D% calc "able" < "baker" 1 When the shell is asked to compare two expressions, it first tries to coerce them to numeric values. This is so that, e.g., a string containing ``16'' compares greater than ``2'' even though a simple string compare would give the opposite result. Pattern Matching Operators The ``=~''and ``!~'' are the ``pattern matches'' and ``pattern fails'' tests. These are done in pretty much the same way wildcarding is done. On the right is a pattern string possibly containing wildcard characters. It's compared against the string on the left the same way a wildcard expansion would be done except that here, comparisons are case-sensitive and where alternation appears, the match succeeds if any of the alternates matches. 302 D% calc "Now is" =~ "N*i*" 1 303 D% calc "Now is" !~ "Now is" 0 304 D% calc "Now is" =~ "n*i*" 0 305 D% calc "Now is" =~ "{n,No}*i{s,the}" 1 Page 102 User Guide Bitwise And, Xor and Or Operators The ``&'', ``^'' and ``|'' operators perform bit-wise and, xor and or operations on integer operands. 306 D% calc 5 & 4 4 307 D% calc 5 ^ 3 6 308 D% calc 5 | 3 7 Logical And and Or The ``&&'' and ``||'' operators perform logical and and or operations: 309 D% calc 5 && 4 1 310 D% calc 0 && 4 0 311 D% calc 5 || 3 1 312 D% calc 5 || 0 1 The ?: Operator The ``?:'' trinary operator selects between two alternate expressions based on the logical (i.e., true or false) value of the first operand. 313 D% calc 0 ? "hello" : "goodby" goodby 314 D% calc (5 > 3) ? "hit" : "miss" hit The {...} Operator The ``{...}'' grouping operator allows you to run a command and evaluate its result as a 1 if it succeeds or a zero if it fails. For example: Page 103 User Guide 315 D% calc {echo hello} hello 1 316 D% calc {cd \nonexistent} csh: Couldn't change the current directory to '\nonexistent'. 0 The Op= Operators Finally, the various ``op='' operators apply the op to the left and right operands, then assign the result to the left operand. 317 D% calc x = 2 2 318 D% calc x **= 500 3.27339061e+150 319 D% calc x 3.27339061e+150 Type Conversions The shell always tries to evaluate expressions ``sensibly'' by doing any type conversions that might seem necessary. If an integer calculation results in an overflow, the shell shifts automatically to floating point. 320 D% calc 2**30 1073741824 321 D% calc 2**200 1.606938e+060 If a character string was given but an integer is needed, the shell tries to do that conversion also. Because these conversions happen automatically, without any fanfare, the following literals all compare equal: 27 27.0 033 0x1B " 27 " ' 0x1b ' (Null strings and strings consisting only of white space are considered equal to zero. This is particularly convenient for local variables, which are initially set to null strings.) The shell does automatic conversions to a character string format when the result is being printed. Numeric results are always shown in decimal. In this example, a procedure, the built-in square root routine, is invoked Page 104 User Guide as a command; the value it returns is converted from floating point to character string and printed. 322 D% sqrt 2 1.414213 The shell also converts to a character string when you reference an array but use it as if it were not. 323 D% set x = Now is the time 324 D% cd ~\samples; myecho $x 'myecho' 'Now' 'is' 'the' 'time' arg length = 23 characters 325 D% @ y = x 326 D% myecho $y 'myecho' 'Now is the time' arg length = 23 characters Page 105 User Guide Aliases Aliases are a quick shorthand technique. If you type an alias at the beginning of a command, it's replaced by whatever the alias is defined as. They're intended to be used for relatively simple abbreviations: if any arguments are needed, you have to be able to type them onto the end. (More complex situations will have to wait until we cover procedures.) To list the aliases currently defined, use the alias command: 327 D% alias cdd cd +c copy local s ; @ s = nowild ; @ nowild = 1 ; safecopy date dt del local s ; @ s = nowild ; @ nowild = 1 ; safedel dir cmd /c dir erase del h history help helpmsg label cmd /c label ll ls -L md mkdir mi more -i rd rmdir ren rename rename local s ; @ s = nowild ; @ nowild = 1 ; saferename ro rotd start cmd /c start type cat vol vl xcopy local s ; @ s = nowild ; @ nowild = 1 ; safexcopy Some aliases are used to intercept references to cmd.exe's built-in commands. For example, this is how dir is run. Other aliases give simple alternate names to a command, e.g., rename for mv. Still others are used to customize a command with a useful option. For example, mi runs more but starts it immediately in interactive mode, which means the screen is cleared first; in a PM text window, this tends to run faster. Page 106 User Guide To find out how any particular alias is defined, use the alias command with only the name you're interested in as an operand. 328 D% alias mi mi more -i To create a new alias, type the alias command followed by the name of alias being created and word list it should be expanded into: 329 D% alias hello echo hello world 330 D% hello hello world If you define an alias that refers to itself, either directly or via other aliases, the shell traps the reference rather than allowing it to expand without limit: 331 D% alias hello (echo infinite; hello again) 332 D% hello csh: A loop in the alias definitions was encountered and trapped. This raises the question how you might define an alias, say, ls, that intercepts references to the ls utility without getting into a loop. The answer is that the shell considers it a special case if the first word in the expansion of the alias is the same as its name. Here's an alias that causes ls to always display all files: 333 D% alias ls ls +a Implementation Details The alias mechanism is actually part of the parsing mechanism rather than a run-time feature of the C shell. What that means is that the alias expansion is done when the statement is first read, not when it's executed. Here's an example where we attempt to change the definition of an alias inside a loop. Notice that it doesn't have any effect until we exit the loop. That's because the whole loop is being compiled as a block before any part of it is executed. 334 D% alias foo echo this is life 335 D% foreach i (hello world) 336 D? alias foo echo $i 337 D? foo 338 D? end Page 107 User Guide this is life this is life 339 D% foo world Page 108 User Guide Programming Constructs This chapter outlines the various structures provided for connecting statements together: describing serial relationships, conditional execution, iteration and how procedures are defined and used. Serial Execution As we've seen already, commands typed on successive lines are executed serially, one after the other. Writing several commands on one line with semicolons between them does the same thing. 340 D% echo hello; echo world hello world 341 D% _ Notice that in contrast to cmd.exe, the shell doesn't pass the semicolon to the application you invoke. If you really do want to pass a semicolon, e.g., to the linker to indicate the end of the arguments, you have to escape it or put it inside quotes. A non-zero return code is not normally considered an error: regardless of the return code from any particular command, serial execution continues. We can demonstrate this with the rcode utility in the samples directory which prints, then exits with the return code value you pass it on the command line. This example also shows how you can retrieve the return code of the last child process by referring to the built-in status variable. 341 D% cd ~\samples 342 D% rcode 1; rcode 2 1 2 343 D% calc status 2 It's also possible to describe a conditional serial relationship. If statements are joined by ``&&'', the second one is executed only if the return code from the first one is 0, i.e., if the first statement succeeds. If statements are joined by ``||'', the second is executed only if the first one fails, i.e., returns a non-zero return code. Page 109 User Guide 344 D% rcode 0 || rcode 1 0 345 D% rcode 1 || rcode 2 1 2 346 D% rcode 0 && rcode 1 0 1 347 D% rcode 1 && rcode 2 1 Statements and Statement Lists I/O redirectors and statement connectors are recognized according to a precedence. Just as in expressions, where ``*'' is done before ``+'', statements are parsed so that some things are done before others. I/O redirection comes before piping which comes before conditional execution which comes before serializing with semicolons. For example: 348 D% echo hello; echo world | wc hello 1 1 7 The shell makes a special distinction between individual statements, no matter how complex, and lists of statements typed on separate lines or separated by semicolons. Here's an example using the time command, which runs a statement and prints out the hours, minutes and seconds it took. time expects a single statement as a operand; if you type a semicolon, the time command (together with its operand) becomes just one statement in the list. 349 D% time echo hello world | wc 1 2 13 0:00:00.50 350 D% time echo hello; echo world hello 0:00:00.00 world Parenthesis There are two ways to group a list of statements together to make them act like a single statement. The simplest way is with parenthesis, which work the way they Page 110 User Guide would in an expression: even if the operator inside the parentheses are of lower precedence, they're done first. 351 D% (echo hello; echo world) | wc 2 2 14 352 D% time (echo hello; echo world) hello world 0:00:00.00 A parenthesized group gets its own copy of the current directory and disk. This makes it convenient to change directories inside the group and go do something without having to change back afterward. 353 D% cd d:\doug\samples 354 D% (cd ..; cd) d:\doug 355 D% cd d:\doug\samples The actual implementation uses the directory stack mechanism: at entry to the group, the current directory is pushed onto the directory stack and at exit, the top entry is popped. 356 D% dirs d:\doug\samples 357 D% ( dirs ) d:\doug\samples d:\doug\samples 358 D% dirs d:\doug\samples Control Structures The more general way of connecting statements together is with control structures, which provide ways of describing conditional or iterative execution or even (with procedures) adding new vocabulary to the language. You can use a control structure anywhere a statement is allowed. The language is completely recursive: control structures can be nested inside control structures, etc. A statement can be arbitrarily complex. Here's an example timing a statement that turns out to be a for loop piped to a wc and inside the for loop ... 359 D% time for i = 1 to 3 do 360 D? time echo hello world | wc Page 111 User Guide 361 D? end | wc 6 12 126 0:00:01.03 If Statement The if statement comes in two forms. The short form is convenient if the choice is only between executing and not executing a single statement, which appears on the same line. 362 D% if (5 == 2 + 3) echo yes yes 363 D% if (5 == 10) echo really 364 D% _ The longer form provides the more traditional if-then- else structure. Indentation is a matter of choice, it's used in these examples merely to improve readability. 364 D% if (5 == 10) then 365 D? echo 5 == 10 366 D? else 367 D? echo 5 is not 10 368 D? end 5 is not 10 369 D% _ Switch Statement The switch statement works by attempting to pattern match the switch value against a series of alternative cases. The switch and case values can all be arbitrary expressions. If any pattern match succeeds, execution begins with the next statement following and continues, skipping over any interspersed case clauses until either the end of the switch block or a break statement is reached. 369 D% switch ("hello world") 370 D? case 5: 371 D? echo hit 5 372 D? case "h*": 373 D? echo hit "h*" 374 D? case "x*": 375 D? echo hit "x*" 376 D? break 377 D? case 43.2: 378 D? echo hit 43.2 379 D? default: Page 112 User Guide 380 D? echo did not hit 381 D? end hit h* hit x* The break statement used here causes execution to ``break out of'' the innermost control structure. If you're nested several layers deep into control structures and want to break out of a higher level structure you can label the higher level structure and specify that name on the break statement. Page 113 User Guide Foreach Statement The foreach statement is designed for iterating over a series of words. In this example, i is iterated over the list of all the files in the samples directory. Each one, in turn, is tested to see if it's executable (i.e., has a .csh, .cmd, .exe or .com extension.) 382 D% cd ~\samples 383 D% ls args.c dumpenv.c finance.csh myecho.exe readme args.exe dumpenv.exe makecpgm.csh rcode.c bits.csh factor.csh myecho.c rcode.exe 384 D% foreach i (*) 385 D? if (-x $i) echo $i is executable 386 D? end args.exe is executable bits.csh is executable dumpenv.exe is executable factor.csh is executable finance.csh is executable makecpgm.csh is executable myecho.exe is executable rcode.exe is executable For Statement The for statement provides more traditional iteration over numerical values. If you specify a range (e.g., ``1 to 3'') but don't specify the increment, 1 is assumed. Although this example shows iteration over integer values, floating point values are equally acceptable. 387 D% for i = 1 to 3 do 388 D? echo $i 389 D? end 1 2 3 You can also iterate over a list of ranges or individual values. The to and by clauses may be specified in either order. 390 D% for i = 1, 4, 7, 12, -4 to 6 by 3 do 391 D? echo $i 392 D? end 1 4 7 12 Page 114 User Guide -4 -1 2 5 While Statement The while statement works in the traditional manner, iterating so long as the while condition is true. This example keeps popping up through the various levels of parent directories until it reaches the root. fullpath is one of the built-in procedures; it return the fully- qualified pathname of its argument. Notice that fullpath is invoked in three different ways: on line 384, as if it were a command, on 385 in more conventional procedure syntax and on 386, where it's substituted in as if it were a variable. 393 D% fullpath . d:\doug\samples 394 D% while (fullpath(".") !~ "[a-zA-Z]:\") 395 D? echo $fullpath(".") 396 D? cd .. 397 D? end d:\doug\samples d:\doug 398 D% cd d:\ Repeat Statement The repeat statement has two forms. In the short form, a numeric constant (not an expression) specifies the number of times to execute the statement following on the same line. 399 D% repeat 4 echo do this again do this again do this again do this again do this again In the long form, repeat provides the more conventional repeat structure, iterating until some exit condition satisfied. 400 D% calc i = 1 1 401 D% repeat 402 D? calc i++ Page 115 User Guide 403 D? until (i > 5) 1 2 3 4 5 Procedures Procedures, as in any high-level language, are a convenient way to package together a series of statements as a more convenient operation. Once you've defined a procedure, you can invoke it simply as if it were a new command. 404 D% proc hello() 405 D? echo hello world 406 D? end 407 D% hello hello world The proc statement can also be used to ask what procedures are already defined or what arguments a particular procedure takes: 408 D% proc hello hello ( ) 409 D% proc | mi abs ( x ) acos ( x ) asin ( x ) : : samepath ( a, b ) sin ( x ) sinh ( x ) --- more --- (Press H for Help) You can explicitly discard a definition with unproc; otherwise the shell remembers any procedure you tell it until you exit the shell or give it a new definition. 410 D% unproc hello 411 D% hello csh: Couldn't find an executable file named 'hello'. When you give the shell a procedure definition, the shell compiles it into an internal form so that the next time you refer to it, it'll save the reparsing time and run much faster. As an example, unproc the whereis procedure to make the shell reload the definition from Page 116 User Guide the .csh file and see what that does to the execution time: 412 D% unproc whereis 413 D% time whereis ls f:\os2\bin\ls.exe 0:00:02.15 414 D% !! time whereis ls f:\os2\bin\ls.exe 0:00:01.28 The namespace for procedures is shared among all the threads: if one thread creates a new procedure, it becomes usable immediately by all the other threads. Arguments You can write a procedure so it expects arguments, just as you would in any other high level language. Argument names are somewhat like local variables: their initial values are set at entry to a procedure, hiding any previous definition; they go away as soon you exit the procedure code. Here's a simple example which compares the timestamps on two files. 415 D% proc comparedates(a, b) 416 D? if (`newer $a $b`) then 417 D? echo $a is newer than $b 418 D? else 419 D? if (samepath(a, b)) then 420 D? echo $a and $b are the same file! 421 D? else 422 D? echo $a is older than $b 423 D? end 424 D? end 425 D? end 426 D% comparedates `whereis more` c:\os2\bin\more.exe is newer than c:\os2\cmds\more.com 427 D% _ When you pass arguments to a procedure on the command line, the individual argument words are paired up, one- by-one, with the argument names you gave. If the shell runs out of names before it runs out of words, the last named argument gets all the remaining words: 427 D% proc xx(a, b) 428 D? echo $#a $a 429 D? echo $#b $b 430 D? end Page 117 User Guide 431 D% xx now is the time 1 now 3 is the time If you pass arguments to a procedure that doesn't take any, they're evaluated but quietly ignored. If a procedure does take an argument, it always get some value, even if it's zero words long. So if you want to know if you got passed a value, just count the number of words: 432 D% proc xx(a) 433 D? echo $#a ">>$a<<" 434 D? if (a == "") echo null argument! 435 D? end 436 D% xx 0 >><< null argument! In a more serious vein, here's a simple procedure definition I use all the time (I have it in my startup.csh file) to implement a real quick and dirty (but very easy to use!) personal phone index: 437 D% proc ppi(name) 438 D? grep -i "$name" h:\phone 439 D? end 440 D% ppi hamilton Hamilton Laboratories 508-358-5715 Fax: 508-358- 1113 As you add lines to your \phone file, you merely add any interesting search phrases or other tidbits onto the same line with the person's name. Totally free format. Add anything you like and search on anything you like and it's fast. Return Values Procedures are also important in expressions, where it's generally useful to think of the procedure as returning a value, just as it might in any other language. The type and value of what you choose to return is arbitrary. Here's a purely mathematical example from finance.csh in the samples directory: 441 D% proc FV_PresentAmount(i, n) 442 D? # Calculate the multiplier to convert $1 now to a 443 D? # future value, given interest rate i 444 D? return 1/(1 + i/100)**n Page 118 User Guide 445 D? end 446 D% # Calculate the future value of $500 invested 447 D% # for 10 years at 8% interest. 448 D% calc 500*FV_PresentAmount(8, 10) 1079.462499 If you call a procedure that returns a value as if it were a command, whatever it returns is printed: 449 D% FV_PresentAmount 8 10 2.158925 Recursion A procedure can call other procedures or even itself. When a procedure calls itself, it's called recursion. Typical uses of recursion are in cases where the problem itself is recursive, or self-replicating. For example, here's a procedure to walk down two directory trees A and B that are thought to be related and list any non-hidden files in A that are not in B. (If you set nonohidden = 1, it'll compare hidden files also.) Page 119 User Guide 450 D% proc comparetrees(a, b) 451 D? local i, f 452 D? foreach i ($a\*) 453 D? @ f = $i:t 454 D? if (! -e $b\$f) then 455 D? echo $b\$f is missing 456 D? else 457 D? if (-d $i) comparetrees $i $b\$f 458 D? end 459 D? end 460 D? end 461 D% comparetrees c:\src\projectx a:\src Notice that i and f were declared as local variables. If the variables were simply set variables, one instance of them would be shared by all the levels of recursion. In this particular example, that would still have worked, but only because each level calls the next only after anything involving f or i has been evaluated; it wouldn't matter if f or i was trampled by the next call. Here's an example where obviously that would not be true: a clumsy attempt at a ``post-order'' traversal of a directory tree: 462 D% proc traverse(a) # Don't do it this way 463 D? foreach i ($a\*) 464 D? if (-d $i) traverse $i 465 D? echo $i 466 D? end 467 D? end 468 D% traverse . | more If you carefully examine the output of this traverse, you'll see that subdirectories don't get listed properly: instead of being listed by themselves, the name of their last child is listed twice. For a correct result, try it again with i defined as a local variable. (Use the <PageUp> key to help you quickly re-enter the lines that stay the same.) Calling a Procedure As you may have spotted, there are two ways to invoke a procedure. Sometimes, the arguments are inside parentheses, separated by commas, and sometimes they're not. What's the difference? The difference is whether the context is an expression or a command. As discussed when we first introduced expressions, the shell always begins to parse statements by first breaking them up into words. That's fine for normal commands, e.g., running an external utility. And Page 120 User Guide it works also when you want to use a procedure as if it were a command, just typing the name of the procedure followed by a list of arguments separated by spaces, e.g., 469 D% proc power(a, b) 470 D? return a**b 471 D? end 472 D% power 2 3 8 473 D% _ But this style of parsing wouldn't be very suitable in those instances where the point is to do some kind of calculation or expression evaluation. So when the shell encounters something that normally takes an expression, e.g., following the calc keyword, or inside the test in an if statement, it shifts to a different style of parsing, further breaking up the words into tokens, so that ``*'' isn't misunderstood as a wildcard, so we don't need to type spaces around all the operators, so we can type variable names without having to put a ``$'' in front of them and so on. All of this is so that the rules for typing an expression can bear some resemblance to those followed by other programming languages like C, Fortran, Pascal, etc. When we call a procedure from within an expression, all these same arguments still apply. We want it to act pretty much like any other high level languages. We want to be able to pass it arbitrarily complex expressions as arguments. We want to be able to take the value it returns and use that value as a term in still other expressions. So there's a real problem: to call a procedure from within an expression and pass other expressions as arguments, we need a way of separating one argument from the next (obviously, it can't be just a space as it would be when the procedure is used as if it were a command) and for separating the whole procedure call and its arguments from the rest of the expression. That's why the common high-level language convention of separating arguments by commas and putting parentheses around the whole list is used. Here's an example of what that looks like: 473 D% calc 5.5 + power(2, 3)*9 77.500000 If you try using a procedure as a command but accidentally type the argument list with parenthesis, it's an error: Page 121 User Guide 474 D% power(2, 3) csh(line 470): Couldn't evaluate expression operands as numeric as required by the expression operator. > in power( "(", "2,", "3", ")" ) defined at line 469 < called from line 474 The reason this is an error is because, since this was typed as a command, the shell took the words following the word power as literal arguments. It couldn't tell you meant this as an expression. Let's redefine that procedure, putting some echo statements in there so we can see what happened: 475 D% proc power(a, b) 476 D? echo a is $a 477 D? echo b is $b 478 D? return a**b 479 D? end 480 D% power(2, 3) a is ( b is 2, 3 ) csh(line 478): Couldn't evaluate expression operands as numeric as required by the expression operator. > in power( "(", "2,", "3", ")" ) defined at line 467 < called from line 480 As you can see, the expression ``a**b'' failed to evaluate properly because a was set to the first argument word, ``('', and b was set to a string concatenation of all the rest of the words. Neither was a number. If you want to call a procedure and substitute the value back onto the command line even when the context is not an expression, it can be done, however. One way is with command substitution: 481 D% echo `power 2 3` a is 2 b is 3 8 This is a bit expensive, though, because the shell will have to create a new thread to run the power procedure and set up a pipe to read the result. And as you see, if the procedure also writes to stdout, you'll pick up that text also, probably unintentially. Another, better way, is to use a dollar sign to introduce the substitution just as if it was a variable substitution: 482 D% echo $power(2, 3) a is 2 Page 122 User Guide b is 3 8 Notice that when use the dollar sign-style procedure reference, the rest of the syntax is as if the procedure had been called from within an expression. The arguments do need to be within parenthesis and they do need to be separated by commas. The reason is just the same one as for why a procedure call in an expression has to be done this way: without the parentheses, there'd be no way to tell where the arguments ended. A nice benefit is that in the argument list, we get to use the full expression grammar: 483 D% echo $power(2, 3*sin(1/2)) a is 2 b is 1.438277 2.709970 Shell Scripts Scripts are a final way of bundling up a series of statements to be called up and executed as a single command. To create a script, create a file with a .csh extension: 484 D% cat >trythis.csh echo hello from trythis ^Z 485 D% trythis hello from trythis When you tell the shell to run a script, it first creates a new thread to run it. This is partly a holdover from original UNIX language definition, partly a response to a provision in OS/2 and NT for threads, but not a fork mechanism and partly due to a genuine need to inexpensively separate some of the script's environment from that of its caller. (The next chapter has a longer discussion of threads.) Shell Script Arguments Arguments to a shell script are passed to it as the argv variable. argv will be a list of any words that appeared on the command line following the name of the shell script. (You can access the name of the script as the scriptname variable.) You can access argv like any other variable: Page 123 User Guide 486 D% cat >tryargv.csh echo $#argv $argv ^Z 487 D% tryargv hello how are you 4 hello how are you There are also some shorthand forms for getting individual words of argv. $0 through $9 is the same as $argv[0] through $argv[9]. (Remember that unless you have nullwords set, subscripting errors will be caught.) ignorestatus If you write a script with serially connected statements the only thing that would cause the shell to quit before it gets to the end would be an explicit failure: an application name that couldn't be found, a child process that terminated with a segment fault, or something else of an equally serious nature. Often in a script, that's not what you want: you've written the script with the expectation that everything will work (as you planned) from one step to the next. If something is wrong, you'd like the script to quit as soon as possible, before any damage is done. The way you do this is by setting ignorestatus = 0, which means you do not want to ignore the status codes coming back to this thread from its children. Here's an example in the main thread: 488 D% set ignorestatus = 0 489 D% rcode 10 10 csh: The child process running 'rcode' exited with a non-zero status = 10. In the main thread, the shell will keep on going and prompt for the next command because interactively that's most sensible. The shell knows to do this because ignoreerrors = 1. But in a script, errors cause the shell to quit: Page 124 User Guide 490 D% cat >trythis.csh calc ignoreerrors set ignorestatus = 0 rcode 10 echo does^'t print ^Z 491 D% trythis 0 10 csh(d:\doug\trythis.csh:line 3): The child process running 'rcode' exited with a non-zero status = 10. > in d:\doug\trythis.csh < called from line 491 csh: The csh script file 'd:\doug\samples\trythis.csh' exited with a non-zero status = 10. Notice that in this case we got two messages, one from the threads executing the script and one from the main thread, reporting what the script returned. Let's return to the normal mode of ignoring status: 492 D% set ignorestatus = 1 source statement The examples so far have shown how a script is normally run somewhat isolated in a separate thread. It is also possible to run a script in your current thread using the source statement. You might want to do this if you wanted to the script to change your current thread's private variables or its current directories or disk. Here's an example to showing how a sourced script runs in the same thread: 493 D% cat >trythis.csh echo argv = $argv, threadid = $threadid ^Z 494 D% echo $threadid 6 495 D% trythis hello world argv = hello world, threadid = 7 496 D% source trythis hello world argv = hello world, threadid = 6 498 D% _ Notice how the argv argument vector is set up the same in either case. Also, notice that the statement number skipped by one. When you source a script, the effect is precisely as if you typed those lines in directly to the shell. The lines read by source are even entered into the history list: Page 125 User Guide 498 D% h 5 494 echo $threadid 495 trythis hello world 496 source trythis hello world 497 echo argv = $argv, threadid = $threadid 498 h 5 Caution: Labels and Gotos We haven't mentioned labels and gotos yet but it probably isn't a surprise that the C shell allows them. Indeed: 499 D% cat >trythis.csh goto next echo this does not print next: echo this prints ^Z 500 D% trythis this prints If you want to use gotos to labels, you should be aware that forward references can be little trickier than a more conventional compiled language. The C shell allows you to redefine a label anytime you like. But if you type a goto that refers to previously defined label, the shell has no way of knowing that you intend it to redefine it up ahead. You can keep running the last example over and over this way with exactly the same result: because a new thread is started each time with no prior definition of next, the shell knows it must be a forward reference. But imagine how repeatedly sourcing this script would fail in an infinite loop: % source trythis this prints % source trythis this prints this prints this prints this prints this prints : (Beware of actually trying this: you may find it difficult to interrupt out of it.) The reason sourcing the script a second time turns into an infinite loop is that the label next is already defined after the first run. The second time, when the Page 126 User Guide goto is read from the script, the history list would look something like this: source trythis goto next echo does not print next: echo this prints source trythis goto next What particularly gets the shell into a muddle is the way this recurses indefinitely: each time through the loop, it recurses through an another level of sourcing. Ultimately, it runs out of stack space and fails. This is not a nice way to treat the shell! In general, it's hard to recommend gotos in any programming language nowadays; in a script you intend to run using source, they can be particularly nasty. The shell does automatically age labels and throw them away after a while even if they haven't been redefined. When it discards a label, it also discards any compiled statements it's been holding onto that could have been executed only by a goto to that label. The cutoff point where the shell begins to discard labels is set by the gotowindow variable. Let's now clean up after ourselves and move along: 501 D% rm trythis.csh Interrupts Normally, when you type ^C, you interrupt the foreground activity. But what if you were in the midst of a complex script and needed to do some kind of cleanup before you exited? What if you wanted to be sure you had a chance to delete any temporary files you might have littered around? The solution is the onintr statement, which allows you to define the action to be taken when an interrupt is received. It causes whatever's running to be interrupted all the way back up to the block in which the onintr routine was defined and for the interrupt routine to be run in that current thread. Within that interrupt routine, you could, for example, remove all your temporary files and goto the end of the script or return a special value from a procedure or whatever else might be appropriate. Page 127 User Guide 502 D% onintr echo hello 503 D% for i = 1 to 5 do 504 D? echo $i 505 D? sleep 1 506 D? end 1 ^C hello Here's another example, returning from a procedure. Note how the value returned (and printed) is the one produced by the onintr statement. 507 D% proc foobar() 508 D? onintr return 5 509 D? for i = 1 to 5 do 510 D? echo $i 511 D? sleep 1 512 D? end 513 D? return 2 514 D? end 515 D% foobar 1 ^C 5 When execution leaves the block in which an onintr is defined, the previous onintr (if any) again takes effect. Note that a null onintr routine does not mean that interrupts are ignored, merely that after processing bubbles back up to the level where that onintr was defined, that it will continue with the next statement. Notice how, in this example, when the ^C is received when obviously execution is stuck in the infinite loop inside bar, that the ``onintr goto xx'' causes a branch to xx in the same block in which the onintr was defined, not the xx in the block where execution was going on. Also, notice that once both procedures have been exited, we're back to the same onintr routine we defined a few statements earlier. 516 D% proc foo() 517 D? onintr goto xx 518 D? bar 519 D? xx: echo this is foo 520 D? end 521 D% proc bar() 522 D? while (1) # Deliberately infinite loop 523 D? end 524 D? xx: echo this is bar 525 D? end 526 D% foo ^C this is foo Page 128 User Guide 527 D% ^C hello 527 D% _ Masking Interrupts In cases where you'd like to simply turn off interrupts or defer processing them, use the irqmask variable. By default, it's set to 0, meaning interrupts will be accepted immediately. Setting it to 1 means interrupts will be deferred until the mask is cleared again. Setting it to 2 means interrupts will be totally ignored. irqmask is a per-thread variable, meaning each thread can independently decide how it will respond to interrupts. Each new thread always starts out with irqmask = 0 (interrupts enabled). Page 129 User Guide Page 130 User Guide Scheduling Foreground Activities Whenever you type any command, the shell's normal behavior is to start up that child activity and then go to sleep waiting for it complete. This is a foreground activity. If you start something and then decide you want to stop it, type Control-C, which wakes up the shell and causes it to stop the foreground activities. Under OS/2, Hamilton C shell can tell the difference+ between full-screen, text-windowable and full Presentation Manager applications and properly spawns new screen groups for applications that can't run in the shell's window. For example, typing the name of the Presentation Manager control panel: 527 D% pmcpl will (or at least, should) cause the control panel to appear in a new window. Similarly, under Windows NT, if you type the name of a graphical application, the C shell will recognize that based on an actual examination of the file itself. Under both OS/2 and Windows NT, when you start an application that needs a new window, the shell comes right back for the next command. Background Activities ____________________ + Actually, under OS/2, the shell depends on the .exe file being properly marked with the application type. Unfortunately, not all developers yet know about and obey this rule. For example, in some releases of OS/2, even IBM forgot to mark some applications such as the control panel. Unmarked applications are, by default, started full-screen; a PM application that's started this way dies immediately. If you spot this behavior, you should mark the offending application using the markexe utility. (Type ``markexe -h'' for more information.) Page 131 User Guide If you want to run something but don't want to wait for it complete, just type an ampersand at the end of the statement: 528 D% wc hello.c >linecnt & 1 529 D% _ This creates a child process to run word count in the background, with its output directed to a file. The ``1'' message means that a new background job (job 1) has been spawned to process the command while you continue to work. The job starts as a new thread. If, as in this case, a separate process is needed, that thread will create it with a DosExecPgm call to the OS/2 kernel (or CreateProcess call to the Windows NT kernel, as appropriate), then exit. Each new thread, process or screen group spawned by a background job will inherit its parent's job number. Every time a new background job is created, the job number is incremented. The use of i/o redirection in combination with a background activity is not accidental. If it's not redirected, it goes to your terminal, intermixing with the output of any foreground activities. Occasionally, that might be exactly what you want. For example, here's a timer to wake you up in 5 minutes (300 seconds): 529 D% (sleep 300; echo ^aWake Up, Sleepyhead.) & 2 : : Beep Wake Up, Sleepyhead. The ampersand works consistently for things that need a new window: 530 D% pmcpl & 3 531 D% _ A new job starts up and announces itself, then realizes that the control panel has to be run in a separate session. Once it's started the child session, the thread exits and its children are adopted by its parent thread and child is left running as job 3. Under both OS/2 and Windows NT, background activities are, in a sense, detached: typing Ctrl-C doesn't interrupt them (unless they explicitly ask to be notified.) You can start a large number of background activities and check on their status using the ps Page 132 User Guide (process status) command. Here's what you'd see on OS/2; the output under NT would be fairly similar. 531 D% ps Job ID Parent State Activity - t1 - running interrupt_handler - t2 t1 running thread_cleanup - t3 t1 running process_cleanup - t4 t1 running screen_cleanup - t5 t1 running keyboard_reader - t6 t1 running main_thread 3 s33 t6 running pmcpl Threads 1 through 4 always run in the background. Each spends most of the time asleep, waking up to do some housekeeping only when an interrupt or the signal that a child activity has completed is received. Thread 5 is dedicated to reading characters from the keyboard on request from other threads. Thread 6 is the foreground command processor. Other entries in the ps report come and go as you type commands. If you want to explicitly terminate a background activity, use the kill command. But do keep in mind that under NT, there are two ways to kill a process: If it's a console (text window) application, it can be done by sending it a Ctrl-C signal; that's what kill does by default. But if it's a graphical application, it can only be done using the TerminateProcess call, a very brute force way of killing something; any DLL's that were being used by that process will not any notification that the process has died and, thus, will not know to do any cleanup they might normally do. 532 D% kill 3 533 D% ps Job ID Parent State Activity - t1 - running interrupt_handler - t2 t1 running thread_cleanup - t3 t1 running process_cleanup - t4 t1 running screen_cleanup - t5 t1 running keyboard_reader Page 133 User Guide - t6 t1 running main_thread Variables and Threads User-defined variables are shared between all active threads unless they're declared as local: if one changes a variable's value, the other threads see that change immediately. Because the individual threads run asynchronously, this can cause some surprising results. In this example, the foreground thread spawns new background threads and increments the variable i faster than the children can execute. By the time any the children actually start, the loop has finished and every thread sees i as having the value 5. 534 D% for i = 1 to 3 do 535 D? echo $i & 536 D? end 4 5 6 537 D% 5 5 5 One solution is to use the eval statement. eval parses the text it's passed at run-time, after any variable substitutions have been done. Because the ampersand is inside the quotes, its special meaning isn't detected until run-time. 537 D% for i = 1 to 3 do 538 D? eval "echo $i &" 539 D? end 7 8 9 540 D% 1 2 3 A better solution is to make i a local variable, since locals are snapshotted and copied when the child is spawned: 540 D% local i; for i = 1 to 3 do 541 D% echo $i & 542 D% end 10 11 12 Page 134 User Guide 543 D% 1 2 3 Re-entrancy Threads also introduce the possibility of re-entrancy. In the next example, we define a procedure for summing all the integers 1 to n. Notice that it works fine if it's run by itself, but gives the wrong answers if two threads try to run it simultaneously: 543 D% proc sum(n) 544 D? @ s = 0 545 D? for i = 1 to n do 546 D? @ s += i 547 D? end 548 D? end 549 D% sum 100 5050 550 D% sum 100 &; sum 100 13 6780 551 D% 7177 Here also, the solution is simply to include a statement defining i and s as local inside the procedure. Threads: An advanced discussion In building Hamilton C shell, a conscious and fundamental decision was made to use threads in many situations where earlier shells might have created separate processes. The result is a dramatically more responsive tool albeit one with some subtle semantic differences from the original. The UNIX C shell language definition called for individual stages of a pipeline, command substitutions and scripts each to be run in a separate process cloned by forking the main process. Using forking, the child inherited all of its parent's state (current directory, open file handles, environmental and set variables, etc.) but any changes it made only affected itself. On a UNIX system with paging hardware and the fork mechanism built into the kernel, it's pretty fast. Page 135 User Guide But OS/2 and the NT Win32 api's do not have fork+, and trying to recreate precisely this language semantic under OS/2 or NT would have been foolishly expensive, potentially adding several seconds to the startup time each time you invoked a shell script. On the other hand, these systems do offer threads. A process can have lots of threads and each one can run along at its own pace. When a thread calls the kernel to do something that takes a long time (e.g., a disk read), it goes to sleep and doesn't wakes up until the data's ready. When one thread goes to sleep, the kernel looks around for another that's ready to run. By using threads, it's possible to ensure that if one thing's got to wait, that won't hold up everything else. Threads turn out to be even faster than a fork (regardless of the hardware), because the amount of state information associated with a thread is so little compared to that of a process. As viewed by the kernel, a thread ``owns'' only a register set, a stack and an instruction pointer. Everything else, memory, current directories, etc., is shared among all the threads in a process. This means creating a thread is very fast, as is switching between threads. On the other hand, using threads to best advantage imposed some significant design challenges in Hamilton C shell. Certainly, for example, few would consider it acceptable if a script running in the background could >Boom< change your foreground current disk! The problem was to create a way for threads to cooperatively share the process resources but without giving away all the performance advantage we'd started with by using threads. Also, some of the elegance of threads is the idea you can keep creating new ones. Each is just like the next: any given thread can run just as complex a program as the next and each can spawn new threads. It would be a shame to lose that recursive characteristic by clumsiness in the language design. Starting with a clean sheet of paper, our solution was a highly multi-threaded architecture. It expects you to start lots of threads: stages in a pipe, background activities, etc. To our knowledge, no other command processor on any system employs this technology. Certainly, all the code in Hamilton C shell is re- entrant: there is a minimum of global, statically- ____________________ + The decision not to provide a fork semantic under OS/2 was probably forced by the decision that initial releases of OS/2 would run on 286-based machines. Lacking paging hardware, a fork on a 286 would likely have been unacceptably slow, no matter how the software was designed. Page 136 User Guide allocated data; the few variables that are global tend to be pointers to the roots of various dynamically-allocated information trees for managing variables, threads, processes, file handles and other resources. When the shell creates a new thread, it creates the appropriate records and links them in. Some characteristics given the new thread are inherited from it's parent and some always get set to specific defaults. Shared variables and other resources are semaphored: before using a resource, a thread requests it; if several resources are needed simultaneously, they're always requested in the same order to avoid deadlocks. Critical resources are held only for short periods. There's no polling anywhere. ``Handle'' mechanisms are used so that, e.g., a thread can decide if its current disk and directories are set up by simply comparing an integer. Path hashing structures are shared with a ``copy on write'' mechanism in case they change directories and need slightly different hash structures. Any thread can do what any other can: compile or execute an arbitrarily complex C shell program or even spawn or pipe child threads. Given the enormous advantage offered by threads and the unique technology we've developed to exploit them, we expect Hamilton C shell should easily outperform any UNIX shell on comparable hardware. Page 137 User Guide Order of Evaluation Finally, to put everything in perspective, here's a summary of roughly the procedure by which the C shell reads, parses and evalutes your commands: 1. The command is read. If stdin appears to be a keyboard, the command line editing routines are used to read a keystroke at a time, entering them into the command buffer and doing whatever editing is indicated. Otherwise, the shell simply uses the kernel's DosRead function to read small chunks until the end of the statement has been found. 2. History substitution is done. The ``!'' and ``%''- style history references are expanded. 3. The text is broken up into separate words. Unless it's part of a quoted string, white space (tabs and spaces) separates words. Also, these special strings are interpreted as separate words even if they're run together with other text: & | ; > < ( ) && || >> << >& >! >&! 4. The command is added to the history list. The fact that this is done after the text has been broken up into separate words explains why the commands in the history list will look a bit different than the way you typed them. It's done this way on purpose so that you can refer to individual words in previous commands, e.g., with ``!$'' to get just the last word of the last command. 5. The command is compiled into an internal form using a recursive descent parser, recognizing the language constructs and whether a given portion of a command is really an expression or just a series of words. Compilation at this stage is at the level of a whole construct, e.g., a whole foreach statement or proc definition and everything inside it. That's so that every time through a loop or every time a procedure is run, the shell won't waste time recompiling statements that could have been compiled the first time. Also, aliases are expanded at this stage and some minor optimizations are down, e.g., pre- compiling static patterns appearing in pattern- matching expressions, etc. Page 138 User Guide 6. The internal form is executed. The various quoting and other substitution activities are done, in effect, in this order: a. Threads are spawned for separate stages of a pipeline or for background execution. That's to avoid serializing any blocking events as, for example, the shell hits the disk, looking through the search path for executable files, etc. By spawning separate threads, those blocking events can be overlapped. b. I/O redirection is performed. If the filename being redirected to/from is actually a wildcard or a command or some kind of substitution, that word will be expanded. c. Single and double quoted strings are processed. If the quoted string contains any wildcard characters, they're escaped so that they'll appear as literal characters when wildcarding is done but still be unescaped right after that. In the compiled internal form, double-quoted strings containing variable or command substitutions are already specially broken up to look, at this stage, like a series double- quoted strings and substitutions concatenated together. d. Variable and command substitutions are done. e. Wildcarding is done. f. Escape characters are processed. g. The series of words is passed to the command as arguments. (It's at this point, if it's an eval command, that the argument text is passed back through the parser and then to the evaluation logic) Commands are searched for in this order: (1) User-defined procedures. (2) Built-in procedures and commands. (3) External commands, searched for in the PATH directories in this order within each directory: .csh .exe .com .cmd .bat Page 139 User Guide (.bat files can be run only under OS/2 2.0 or Windows NT.) 7. The internal form of each compiled statement is discarded once it's no longer needed, i.e., if there's no way you might invoke that code from a later statement. For example, once you define a procedure, it's always accessible; you can call it at any time, so that compiled code is never discarded unless you redefine the procedure or explicitly unproc it. But an ordinary statement typed at the command line could be re-run (without re-entering it using history or by retyping it) only if it was part of a larger control structure or if there was a way to goto it, meaning there would have to have been a label preceding it. Page 140 User Guide Customizing the Shell Depending on your tastes and what you're used to (and whether you come from a DOS or a UNIX background), Hamilton C shell can be customized in a number of ways. This section will outline: 1. Various options you have when installing the shell, including setting it up as the default command processor, 2. How shell starts up, and how it uses the login.csh and startup.csh files, 3. How to set the environmental variables, screen colors and the prompt strings, 4. How to create aliases you always want available, 5. Customizing the cd command and how history references work, and 6. Telling the shell how it should respond to certain special situations. Installation Options You have a fair amount of choice about where the various files associated with Hamilton C shell go and also about how it starts up. You won't necessarily want to fool with all this when you first install the shell, but you may want to look at some of this as you get a sense of your own preferences. The C shell .exe and .csh files can go anywhere as long as they're on your search path. Most people find it most convenient to keep them in a separate directory. We do suggest it be ahead of the directory containing the standard more.com on your search path since we provide a new, vastly improved more. You choose any directory on any drive as your ``home'' directory. The significance of a home directory is that the shell will make references to it or relative to it very convenient using the ``~'' wildcard character. Also, this is where the shell will look for your login.csh and startup.csh files. If HOME isn't defined in the environment when the shell starts up, it defaults Page 141 User Guide to the current directory. It's usually most convenient to define the HOME variable in your config.sys but if you prefer, you can pass it to the shell on the command line using ``-C setenv HOME=...'' (The ``-C'' means what follows is a command.) Additional customization is usually done with the login.csh and startup.csh files. Installing as the Default OS/2 Command Processor OS/2 gives whatever default command processor you specify on the PROTSHELL line of your config.sys special privileges to change its own title bar and, under OS/2 1.3 or 2.0, its own icon. This can be quite useful if you have a lot of copies of the shell running minimized and you'd like to know what they're doing. Under OS/2 1.1 or 1.2, the C shell uses the undocumented DosSMSetTitle kernel api entry to change its own title; under 1.3 or 2.0, it uses the new WinSetTitleAndIcon api to change both the title and icon. Unfortunately, these api entries are disabled if you're not running in a window whose root process was the default command processor. To install the C shell as the default command processor, follow the instructions given in the installation section of this manual. In a nutshell, the idea is to replace the reference to cmd.exe and any parameters to cmd.exe on the PROTSHELL or OS2_SHELL (under 2.0) line with the full pathname of the C shell plus a ``-L'' option to indicate it's a login shell. Next, fixup the entries for cmd.exe and the C shell in the Group-Main or Start Programs menus. To make it a default command processor, the C shell must be listed with an ``*'' (asterisk) for a pathname (on the ``Path and file name:'' line if you pull-down ``Program'' and select ``Properties...' in Group-Main) or else the title bar and icon changes will be disabled. Also, for some reason, if you specify any startup parameters (other than ``/K "%*"''), that also disables the title and icon changes. (The ``/K "%*"'' option has special significance for the default command processor and is used when OS/2 boots up if it finds a startup.cmd file in the root directory; otherwise, it's ignored.) Conversely, you have to change the asterisk path and any arguments for the cmd.exe entries to the actual path for cmd.exe and enter whatever arguments (if any) you had Page 142 User Guide been specifying for it on the PROTSHELL or OS2_SHELL line in your config.sys. login.csh login.csh is read only by copies of csh.exe started with the ``-L'' option to make them login or root shells. Typically, this is a new window. startup.csh is read by each new copy of the shell, even if it's invoked as a child of the C shell. The main objective of the login.csh file is to let you set up those characteristics that are inheritable from parent to child process but which might not be set up if you're starting from the Start Programs menu (OS/2 1.1), a Group menu (OS/2 1.2 or 1.3),from the desktop (OS/2 2.0) or from the Program Manager (Windows NT). In addition, it lets you do a little special customization of these highest-level shells. The important inheritable characteristics are the environmental variables together with the current directories and current disk settings. Page 143 User Guide The Environmental Variables Most users prefer to create the bulk of their environmental variables with SET statements in config.sys under OS/2 or through the Control Panel under Windows NT (to be inherited by every process on the system) rather than in login.csh. It means just one copy of the definitions in one place, so it's easier to make changes. It also runs faster since it's all set up when the shell starts; the shell doesn't have read all those commands. But if you're using an initialization script to set some of your environmentals for cmd.exe, you'll want to do that for the C shell also in login.csh. But there are cases where it's more convenient to set up some environmental in your login.csh. For example, you might prefer to set your PATH statement there. Since the C shell hashes your search path, you'll find it's much faster finding things even with a very long list of path directories. (If you actually had 50 or so directories, the difference in startup time for something in that last directory would be around 6 seconds or so!) So you might find it more natural to have a much longer PATH with the C shell than with cmd.exe. Also, if you were going to use an application that needed mixed case characters in some of its environment strings and you were running on OS/2 1.1, you'd want to define them in login.csh, not config.sys. (Using lower case characters in config.sys was unreliable on OS/2 1.1; many users found it caused random system failures, e.g., OS/2 crashing while formatting a series of floppies.) In addition to PATH, the environmental variables used by Hamilton C shell include HOME, PROMPT1 and PROMPT2, TABS, CDPATH, DRIVEMASK, MIXEDCASEDRIVES, SWITCHCHARS and a number of screen color configuration variables. PROMPT1 or PROMPT2 or their aliases prompt1 and prompt2 control the prompt strings you'll see for a new command or a continuation line. TABS is used by more.exe, head.exe, tail.exe and other utilities to expand out any tab characters it sees into space characters on the screen. For example, setting TABS = 3 means tabstops every 3 character cells. CDPATH is used by cd and pushd to specify other directories in addition to the current directory in which to search for a subdirectory you're trying to change to. Its format is the same as that as PATH: a list of directories separated by colons, but there's no need to list the current directory. Page 144 User Guide DRIVEMASK lets you confine the default list of drives you want the du, pwd and vol utilities to report on. The value should be a list of upper- or lower-case alphabetic characters or ranges of characters representing the drives you're interested in. For example, setting DRIVEMASK = cf-h means you want drives C:, F:, G: and H: reported, assuming they exist. MIXEDCASEDRIVES is used by ls.exe, by the shell's wildcarding functions (including filename completion), by the current directory functions (cd, pushd, popd and dirs) and by pwd.exe to tell which drives you want reported in the actual upper or lower case characters returned by the OS/2 kernel. If you have HPFS drives, it's possible to create filenames that have mixed upper and lower characters and you may not want these all routinely shifted to lower case. You set MIXEDCASEDRIVES just like DRIVEMASK, giving it a list of drives. SWITCHCHARS is used by the shell and all the utilities supplied with it to indicate what characters you intend as introducing one of the option switches. By default, the C shell tries to satisfy users coming from both DOS, OS/2 or NT and UNIX backgrounds and will accept either ``-'' (DOS-style) or ``/'' (UNIX-style) as introducing an option. Folks coming from a straight UNIX background may find that inconvenient, particularly if they're used to typing filenames using the forward slash; ``cd /foo'' will certainly not do what they want, for example. The solution is to ``setenv SWITCHCHARS = -'', causing only those words that start ``-'' to be recognized as options. Prompt Strings Prompt strings are fairly personal matter. This really is beauty in the eye of the beholder only! There are two prompt situations: 1. The main prompt, when the shell expects a new command. Set this with PROMPT1. 2. Continuation lines, where the shell is collecting more text before running something. An example would be whatever commands you type inside a foreach loop. Set this with PROMPT2. When the shell needs to prompt you, it looks at the appropriate PROMPTx string and evaluates it as if it were looking at a double quoted string. Any backquoted strings or variable substitutions it finds there are evaluated and whatever results is printed. Wildcards are not replaced nor is the spacing affected. It's quite Page 145 User Guide literally double-quoted: the shell actually pastes double quote characters around the string before passing it to the parser. If you always wanted the same literal text string displayed, that would be easy but probably not too interesting: 543 D% set PROMPT1 = "Hello from CSH! " Hello from CSH! _ The difficult part of setting your prompt is remembering that if you want a substitution re-evaluated each time a new prompt is printed, you have to quote the string when you define it to defer the evaluation. Here's the wrong, then the right way to create a default IBM-style prompt with your current directory inside rectangular brackets. Hello from CSH! set PROMPT1 = "[$upper(cwd)] " # Wrong way [D:\DOUG] cdd c:\ # Notice that the prompt won't change [D:\DOUG] set PROMPT1 '[$upper(cwd)] ' # Right way [C:\] _ Notice how we're using the built-in upper procedure as if it were a variable substitution with the ``$'' in front. When the shell sees it's really a procedure reference, what's inside the parentheses is evaluated as an expression list. That's why the cwd variable didn't need its own ``$.'' There's really no limit to what you can put inside a prompt string. You can have command substitution and special characters. It can even stretch over multiple lines if you put in carriage return/newline character combinations: [C:\] set PROMPT1 = '`date`^r^n$cwd ' Mon Oct 23 1989 11:15:15.03 c:\ _ The tradeoff to remember in creating your prompt string is that whatever you put there is going to be run every time you need a new prompt. If you make it too complex, it'll still run, but it could be annoyingly slow. Remember that it takes longer to run external programs than to use shell variables or procedures. If you want something really unusual, try writing a procedure that calculates and returns the string you want. Page 146 User Guide User-Defined Colors All of the screen colors used by the C shell and any of the utilities are completely under your control. Here are the variables that control the color settings and default values: Name Use Default ADDITIONS Lines added found by diff. Bright Green COLORS Normal screen colors. White on Black DELETIONS Lines deleted found by diff. Bright Red DIRECTORIES Directories listed by ls. Bright DUPLICATES When filename completion matches Green more than one name. FOREIGNFILES Filetypes in a tar file that have no Br ight Red counterpart on OS/2 or NT. HIGHLIGHT Current disk or directory. Bright MATCHFAIL When filename or command completion Br ight Red doesn't match anything. MOREEOF End or Top of File in more. Green MOREERROR Unrecognizable command to more. Bright Yellow MOREFILLIN User response to more prompt. White MOREPROMPT Prompt line in more. Green MORETOPMEM Top of Memory message from more. Bright Yellow SYSTEMDIRS Directories with the System bit on. Br ight Green SYSTEMFILES Files with the System bit on. Green You can choose any color combinations you like from the following set: black, red, green, yellow, blue, magenta (or blue red), cyan (or blue green) and white. Foreground colors may also be bright, dim (meaning simply, ``not bright''), blink or reverse. The keyword ``on'' introduces background colors. Blink only causes true blinking full-screen; in a text window, it just makes the background brighter. Also, yellow is a true yellow only if it's bright. These are system limitations not related to the C shell. The names of the colors and the keywords bright, dim, blink, reverse and on are not case sensitive and may be typed in any combination of upper or lower case characters. The names of the environmental variables themselves must be all in upper case. If a foreground or background color is left unspecified, that plane is considered transparent and inherits the color underneath it. Page 147 User Guide You can set the colors either from within the C shell itself by simply typing the appropriate setenv statements or by including them in your login.csh file. Here's an example color scheme that's a little more colorful than the defaults: setenv COLORS = white on blue setenv DELETIONS = bright white on red setenv ADDITIONS = bright white on green setenv MOREPROMPT = red on white setenv MOREFILLIN = black setenv MOREERROR = bright white on red On OS/2, you might also choose to place these settings into your config.sys as the corresponding SET statements: SET COLORS=WHITE ON BLUE SET DELETIONS=BRIGHT WHITE ON RED SET ADDITIONS=BRIGHT WHITE ON GREEN SET MOREPROMPT=RED ON WHITE SET MOREFILLIN=BLACK SET MOREERROR=BRIGHT WHITE ON RED (Notice that if you choose to use SET statements in config.sys, you should be sure not to leave any space around the equal signs. Also, unless you're running OS/2 1.2 or later, type everything in upper case.) Or, on Windows NT, these settings could be made through the Control Panel. Initial Current Directories The login.csh file is also a convenient place to set up all you initial current directories. The Start Programs menu lets you specify a particular current disk and directory but not what your current directories are on the other disks when you start up; the current directories on those other disks are always ``\''. Generally, people find it convenient to be able to choose something else and they do this by putting the appropriate ``cd'' statements in login.csh. The final use for login.csh is in setting up certain local variables that you want different in the login shell. For example, a login shell normally dumps a history list when it exits; you may want to turn this off by setting savehist = 0. Also, you may not want an end- of-file (from accidentally hitting ^Z once to many times) to cause the shell to exit; you can tell to insist on an exit statement by setting ignoreeof = 1. Page 148 User Guide startup.csh The startup.csh file is read by all copies of the C shell, not just login or root level copies. If you don't want the startup file read, you have to specifically tell it with the ``-F'' (Faster startup) option. startup.csh is read after login.csh whenever both are being read. This means you can depend on the environmental variables being set up already when the startup file runs. startup.csh is a good place to define any aliases or function key definitions you use, since you'd probably always want them available but can't pass them in the environment to any child copies of csh.exe. The startup.csh file that comes with the shell defines a number of popular aliases including some for getting at some of cmd.exe's internal functions; most people add a few of their own. The other thing you may want to add to your startup.csh file are settings for some of the set variables that customize how the shell runs. These aren't passed in the environment. Look through the lists in the Language Reference section. Some you may want to set differently than the defaults are bsdhistory, cdhome, chgdisk, escapesym, histchars, ignoreerrors, ignorestatus, noclobber, nonomatch, nullwords and tailstatus. A lot of what you choose will depend on whether you're coming from a DOS or a UNIX background. Change Directory If your background is DOS, you'll probably want cd to just report the current directory if you don't give it an argument. Those with a UNIX background may want it to mean ``change to the home disk and directory.'' That's determined with the cdhome variable; the default is a DOS-style reporting only. Another customization you may to do is to intercept cd so that you can capture your last current directory whenever you change directories: proc cd(dest) @ lwd = cwd # capture the last working directory if ($dest == "") chdir else chdir $dest end end Page 149 User Guide Berkeley-style History and Escapes Also, if your fingers learned to use the ``!-n'' style of history references on a Berkeley UNIX system, you'll want to set bsdhistory = 1. True die-hard (and perhaps daring) former UNIX users may want try setting the escapesym back to a backslash; it'll work with the C shell but you're on your own with other applications or tools. Berkeley Compatibility Mode Hamilton C shell does implement a substantial number of significant improvements over the over original Berkeley C shell. By and large, we expect most users to find these changes welcome. But if you're trying to run a script developed using the Berkeley C shell or if you simply want get a more precise ``Berkeley mode'' interactively, you can do that. Following a common convention on UNIX that the first line of a script can identify the language processor to be used with it, if the C shell encounters a script that starts with #!/bin/csh it will shift to a fairly precise emulation of the original Berkeley C shell. To enter this mode for interactive work, start the C shell with the ``-B'' (Berkeley compatibility) option. For more details on differences between the Hamilton and Berkeley C shells and on Berkeley compatibility mode, please please refer to the Compatibility section beginning on page 162. Error Handling ignoreerrors, ignorestatus, noclobber, nonomatch and nullwords let you tailer how the shell responds to various exception situations. They let you determine whether you think certain things are errors. For example, should a child process that returns a non-zero return code but otherwise seems to run okay be considered an error? If you set ignorestatus = 0, it will be. Similarly, noclobber lets you intercept accidental attempts to overwrite an existing file with i/o redirection. nonomatch tells what should happen if Page 150 User Guide wildcarding doesn't match anything. nullwords tells whether you think it's an error to use a subscript that's off the end of an array. Calling the C shell from Other Applications Many applications, e.g., editors, make utilities and so on, depend on being able to call up the command processor. For example, make uses cmd.exe to actually process each command in the make file that it determines should be run. Most editors (and many other applications) provide a way of temporarily suspending themselves and invoking cmd.exe so you can run a few commands and then exit to return back to the editor. Usually, these applications look at the COMSPEC environmental variable to determine the full pathname for cmd.exe. If, like make, they're just calling it with a single command on the command line, they use cmd.exe's /C option. If you'd like to use the C shell instead of cmd.exe with these applications, set COMSPEC to point to the C shell instead and use the CSHOPTIONS environmental variable to tell the C shell to interpret the /C option flag in a way that's compatible with the meaning cmd.exe would attach to it: setenv COMSPEC = c:\hamilton\bin\csh.exe setenv CSHOPTIONS = -X Alternately, you can put these definitions right into your config.sys, rewriting them as: set COMSPEC=c:\hamilton\bin\csh.exe set CSHOPTIONS=-X When the C shell starts up, if it discovers that COMSPEC points to itself, it will look through the search path to find the real cmd.exe. This is to make sure it will still be able to run .cmd files. Since the -X option is a toggling option, you can still get at the original meaning of the -C option by typing -XC to toggle back. Page 151 User Guide Page 152 User Guide Summary The next few pages show a couple of somewhat more full-blown examples and outline the contents of the samples directory. There's also detailed discussion of the compatibility issues between the Hamilton and original Berkeley C shells. Try some experiments. We hope you'll find this product powerful, fast, reliable and easy to use. We hope it will help you get your work done faster and perhaps, more pleasantly. Page 153 User Guide Page 154 Examples Examples Factor.csh: A self-loading procedure which prints a list of the factors of a number, illustrating the use of recursion. proc factor(n) if (n > 2) then for i = 2 to floor(sqrt(n)) do if (n % i == 0) then echo $i return factor(n/i) end end end return n end factor $argv Invoked as: factor 6324489 It would print: 3 3 702721 To print the factors on one line and time how long it takes: time echo `factor 6324489` The `...` sequence means command substitution: run what's inside the backquotes and substitute the output back onto the command line. This would print: 3 3 702721 0:00:02.35 Page 155 Examples Whereis.csh: A self-loading procedure to find all the files anywhere on the search path corresponding to the command name, illustrating pattern matching and file system tests. proc whereis(name) local i, j if (name =~ "*.*") then foreach i ($path) if (i =~ "*\") then if (-e $i$name) echo $i$name else if (-e $i\$name) echo $i\$name end end else foreach i ($path) if (i =~ "*\") then foreach j (.csh .exe .com .cmd) if (-e $i$name$j) echo $i$name$j end else foreach j (.csh .exe .com .cmd) if (-e $i\$name$j) echo $i\$name$j end end end end end whereis $argv Invoked as: whereis ls It would print: c:\os2\bin\ls.exe ls.exe is the file directory lister. Invoked as: time ls -l `whereis more` It would show the two versions of more. (Our more ``is less filling and tastes better.'') ---A- Mar 20 8:00 20123 c:\os2\hamilton\more.exe ---A- Oct 26 12:00 31658 c:\os2\ibm\more.com 0:00:00.97 Page 156 Examples Samples Directory The sample C programs and C shell scripts in the samples directory are meant to help you install or experiment with Hamilton C shell. Deliberately, they're relatively trivial. All were created assuming TABS=3. args.c A simple C program that prints out the *argv[] (argument) and *envp[] (environmental variable) arrays. Notice that wildcarding, variable substitutions, quoting and command substitutions are done before the C program is started. If you do a lot of wildcarding, you can create and pass VERY long parameter lists (up 64K characters.) Try some of these commands: % args "ho"w 'no'w % args "$cwd" '$cwd' % args * "*" '*' % args `whereis more` % args '`whereis more`' % args * *\* *\*\* | more bits.csh A simple self-loading procedure that calculates the minimum bits required to represent the argument it's passed as a binary integer. bumpdate.csh Print the date n number of days forward or backward from a given date. If only the bump value is given, today's date is bumped. caldate.csh Print the date corresponding to a given Julian day. calendar.csh A C shell script for printing out the calendar for any given month, highlighting the current date. If no date is given, this month's calendar is printed. colors.csh Instructions and examples on customizing the screen colors. cl.csh On NT only, run the compiler and linker for an NT program. Avoids having to fool with a make file just to compile hello, world. Works pretty much just like the cl command on DOS would. Page 157 Examples deltaday.csh Print the number of days separating two dates. If only one date is given, the difference between it and today's date is returned. dumpenv.c This C program writes out the environment it's passed in the form of setenv commands. If you're installing Hamilton C shell for the first time, dumpenv is a convenient way to snapshot the environmental variables you've been using with cmd.exe in a form you can append to your login.csh file. duplicat.csh Look for duplicate files anywhere in a directory tree. easter.csh A C shell script that calculates when Easter will occur in any given year. If no year is given, the current year is assumed. factor.csh The simple factor C shell script shown in the User Guide. It's intended to show to show the use of recursion, expressions, and a self-loading procedure. finance.csh Another C shell script showing expression evaluation. This defines a number of routines for calculating financial conversion factors, e.g., from present to future value. getprio.c This C program (supplied with the OS/2 version) retrieves and prints its scheduling priority, demonstrating the effect of using the eval command to run a command at a higher or lower priority. Try these examples: % getprio % eval -i getprio % eval +20 (getprio; eval +20 getprio; getprio); getprio julian.csh Calculate the Julian day number (number of days since January 1, 4713 B.C.) for any given date. If you don't give a date, it uses today's date. makecpgm.csh A simple C shell script (supplied with the OS/2 version) showing how a ``make'' function might be written in the C shell language. This one rebuilds any .exe Page 158 Examples files in the current directory that are older than the corresponding .c file or any of the .h files. In fact, the .exe's in this directory were built with this script. mcvisa.csh A simple C shell script that constructs a special checksum of a credit card number to tell if the card number is plausible or not. The checksum used is designed to catch transposed or incorrect digits. Try it on the cards in your wallet. myecho.c A variation on the built-in echo command that prints its *argv[] (argument) list with quotes around each word it's passed and tells the total character count. Try these examples: % myecho now is the % myecho "now is" the % myecho `ls` % myecho `echo` % myecho `echo hello` % myecho * *\* *\*\* | more newfiles.csh List all the files or directories in the current directory that do not occur in the specified directory. postage.csh Calculate the U.S. first class postage required for a given weight in ounces. rcode.c A trivial C program that just prints, then exits with the return code value you pass it. You can use this routine to see how the status variable is set and also, how the ``;,'' ``||'' and ``&&'' statement connectors work. Try these examples: % rcode % calc status % rcode 1 % calc status % echo $status % echo status % rcode 2 % calc status % rcode 0 || rcode 1 % rcode 1 || rcode 2 % rcode 0 && rcode 1 % rcode 1 && rcode 2 % rcode 0 ; rcode 1 % rcode 1 ; rcode 2 Page 159 Examples rcode also illustrates another aspect of return codes to consider: if you use C library stdio (as rcode.c does) and you exit with a non-zero return code, stdio thinks it was an error and discards anything in the stdio buffers. In the following example, stdio writes to the screen are unbuffered so it works; but pipes are buffered, so nothing gets written to it: % rcode 1 1 % rcode 1 | more --- End of file --- % If you're writing an application that uses return codes, you should remember to explicitly flush the buffers with stdio fflush() or use the kernel routines, e.g., DosWrite(), directly sizeof.csh A short C shell script that calculates and prints the cumulative size of any number of files or directories. ts.csh A C shell script that searches for occurrences of a simple string in all the files with a given extension anywhere in a directory tree. viopaste.c A short C program (supplied with the OS/2 version) to enable pasting into a Presentation Manager text window under OS/2 1.2 or 1.3. weekday.csh Print the day of the week corresponding to any given date. Page 160 Examples Page 161 Compatibility Compatibility Guide This section details the specific differences between the Hamilton C shell and the original UNIX C shell+. It also describes the Hamilton C shell's Berkeley compatibility mode, used for running Berkeley C shell scripts. Berkeley 4.3 Buglist problems have been fixed. 1. Shell procedures have been provided and the clumsy argument mechanism for aliases has been dropped. 2. Commands typed within loops or other control structures are properly added to the history list. 3. Control structures are recursively parsed, allowing piping between them. For example: foreach i (a b c) echo $a; end | wc properly displays 3 3 12 4. Any of the `:' editing modifiers can be used on any substitution. Also, a space inside the search string in a ``:s/.../.../'' command will match the space between two words. In the UNIX C shell, only certain modifiers could be used on a given type of substitution and it is not possible to perform a search/replace that crossed word boundaries. The language has been regularized. 1. The set, setenv and alias commands will now accept the same basic syntax. The UNIX C shell had a number of anomalies: an `=' sign was required for a set but not for setenv and alias; parenthesis were required around a word list for a set but not for setenv and alias; the set statement ignored all but the first argument word but alias would not, etc. ____________________ + The references used for comparison are the Berkeley 4.3 Unix User's Manual: Reference Guide (University of California, 1986) and The UNIX C Shell Field Guide by Gail and Paul Anderson (Prentice-Hall, 1986.) Page 162 Compatibility 2. Variables or word lists are always indexed counting the first word as element zero. The UNIX C shell counted from zero when indexing with ``:n'' notation but from one when using ``[n]'' notation. argv[0] is the first argument word, not the name of the shell script being executed. The name of the script is kept in the local variable $scriptname. This can be overridden by setting the inheritable per-thread variable bsdargv = 1, causing argv[0] to be the name of the script. 3. In keeping with the desire to consistently index from zero, the last command entered into the history list, ``!!'', is considered the 0-th element; ``!- 1'' is the line before it. The UNIX C shell considered these to be the same. A built-in variable, bsdhistory, is provided for those whose fingers prefer the Berkeley numbering convention: if you set bsdhistory = 1, ``!!'' and ``!-1'' are the same. 4. Where an expression is expected, conventional high level language syntax is now acceptable. The UNIX C shell required spaces around any expression operators, a variable reference required a `$' to introduce it, parenthesis were required to avoid confusing ``less than'' with i/o redirection, etc. What had to be typed as @ i = ($j + 3 * $k < 10) under the UNIX C shell can now be typed (for example) as @ i=j+3*k<10 (The original UNIX C shell expression syntax is still entirely acceptable and will still produce correct results.) 5. Inside a ``[...]'' array index, the shell always looks for an expression, never an editing-style word select. Syntax and keying rules are the same as with any expression. 6. The case statement now accepts an expression to be matched rather than only a pattern. (To specify a static pattern, enclose it in quotes.) To determine a match against a case clause, the case expression is evaluated, converted to a string and then used as a pattern to compare against the switch value. 7. The various different end statements used by the UNIX C shell, end, endif and endsw, have been Page 163 Compatibility replaced by a single end statement. Similarly, the two break statements, break and breaksw, have been replaced with a single break statement. For compatibility with existing scripts, the obsolete keywords are implemented as aliases. 8. Since Hamilton C shell is free format (i.e., new statements need not begin on a new line), the UNIX C shell convention of chaining if statements with a single end if the else and if are on the same line isn't possible. Instead, an elif keyword has been added. 9. The obscure use of several break statements in a row on a single line to break out of several levels of control statements at once has been eliminated. In its place, a label may be specified as an operand to indicate the control structure to ``break'' out of. 10. The $* notation for accessing the argv array is not supported in the current release. (It may be in a future build.) Use $argv instead. Page 164 Compatibility Modern compiler technology has been employed. Statements are parsed and compiled into an internal form before any substitutions or other evaluation is attempted. This offers an enormous performance improvement, particularly when iteration is involved. (The UNIX C shell would actually reparse each statement inside a foreach loop each time through the loop.) If command- or variable-substitution creates any of the following reserved words or tokens, the special semantic meaning will be lost since substitution is done after parsing of statement structure. Instead, they will simply be treated as character strings. These reserved words are: Introducing a clause in a structured statement: alias elif if setkey unproc break else local source unset by end onintr switch unsetenv calc eval proc then unsetkey case exit repeat time until continue for return to while default foreach set unalias @ do goto setenv unlocal Anywhere: ( ) < > & | ; In an expression: + - * / % = Similarly, labels cannot be run-time evaluated to see what the label on a statement is; it must be evaluated when the statement is first parsed. Extensions: 1. Command line editing with the arrow keys, etc., and the setkey statements are new. 2. The procedure mechanism, including the proc, unproc and return statements and the various built-in procedures, is new. 3. Local variables and local and unlocal statements are new. Page 165 Compatibility 4. The use of color highlighting to indicate exception situations in filename or command completion is new. 5. The for statement, providing numeric iteration, and the calc statement, which writes the result of expression evaluation to stdout, are new. 6. The ``**'' and ``**='' exponentiation operators are new. 7. Floating point arithmetic is new. 8. The path hashing mechanism is substantially less sensitive to blindspots caused by creating a new executable in one of the path directories and not manually specifying rehash. The UNIX C shell would not be able to find the new file; this shell makes a second pass through the path directories whenever hashing fails, looking for this sort of problem before it reports failure. If it finds a blindspot, it automatically rehashes that directory. 9. History references are allowed in the inline text supplied with the ``<<'' i/o redirection mechanism. Also, the inline text is remembered in the history list, each line as a single word. This avoids the user having to remember and retype the inline text any time one of these statements is recalled from the history list or if the history list is dumped for use in a script file. 10. Exclusion ranges, e.g., ``[^a-z],'' can be used in a wildcard pattern. 11. Escape sequences to encode special characters (e.g., ``^a'' for audible bell or ``^b'' for backspace) are recognized in the arguments to any command, not just echo. Because this processing is internal to the shell, it is not necessary to type two escapes in a row to access this feature. (Refer to the echo command help screen for a complete list.) 12. Argument lists passed to a child process can be much larger than are allowed under UNIX. The UNIX C shell allows only roughly 6K characters to be passed, depending on the revision level; this shell allows up to 64K to be passed to a child process under OS/2 or 32K under NT, the kernel limits on these systems. There is no command line limit to an internal command such as echo. This is of particular importance when wildcarding is used heavily. Page 166 Compatibility 13. Quoted strings are shown in the history list exactly as they would have to be typed. (The Berkeley UNIX C shell marked a character as quoted by setting its high-order bit; setting aside portability issues, it had the side-effect of not being visible in the history list.) 14. Parentheses in an argument list to an executable statement need not be escaped, so long as they are matched. Semicolons, i/o redirection symbols, etc., inside these parentheses are treated simply as text and are passed straight through to the application. 15. The ``:b'' (base) and ``:#'' (count) editing operators are new. 16. The indefinite directory wildcard construct, ``...'', is new. Restrictions and unimplemented features: 1. History references as way of picking up alias arguments are not supported. Procedures should be used instead. 2. Job control is not supported. Job control is not currently feasible under Windows NT or OS/2 because once one thread from any process within a window has started to read the keyboard, the read can not be interrupted. (Fortunately, one can always open more windows.) 3. The use of ``\!'' inside a prompt string to get the statement number is not supported. Use $@ or $stmtnumber instead. 4. The following statements, all fairly specific to UNIX, are not supported: alloc, glob, limit, notify, stop. 5. The comment character, #, must be followed by some white space to be considered the start of a valid comment. Adaptation for OS/2 and NT: 1. OS/2 and Win32 NT do not provide a fork( ) call for inexpensively cloning an independent copy of a running process, complete with its own separate memory image. Instead, OS/2 and NT provide a faster Page 167 Compatibility alternative called threads, which creates an separately scheduled flow of control through the memory space of a single process. In general, the Hamilton C shell spawns a new thread anywhere the Berkeley UNIX C shell would have used a process. Using a new thread instead of a new invocation of the Hamilton C shell saves over a second each time. Individual threads manage their own notions of current directories and current disk and certain per-thread variables but the dictionary of aliases, procedures and most variables is shared among all threads. The result is that background activities and C shell scripts can change variables, define procedures, etc., for use by the other threads. For example, procedures can be written as self-loading scripts. (See the whereis.csh file for an example.) 2. OS/2 and NT conventions are followed: either the ``\'' or the ``/'' characters can be used in a filename; the ``^'' character is normally the escape character; directories in the PATH environment variable are separated by semicolons, etc. 3. Labels cannot be a single letter. (This is to avoid confusing the drive letter in the pathname of an executable file as a label.) 4. Since OS/2 and most NT filenames are case- insensitive, they are routinely translated to lower case for better readability. (This can be overridden using the MIXEDCASEDRIVES variable.) 5. Executable files are recognized by their extension. The following extensions are recognized (in this order): .csh, .exe, .com, .cmd, .bat. .csh files are interpreted as C shell scripts by a new thread, .exe and .com files are executed with the DosExecPgm and DosStartSession kernel functions under OS/2 or with the CreateProcess kernel function under NT, .cmd files are interpreted by a child process running cmd.exe, and .bat files are passed to a Virtual DOS machine (VDM) under OS/2 2.0 or to cmd.exe under NT. 6. PROMPT1 and PROMPT2 variables are used to set the primary and secondary prompt strings. Using the UNIX C shell variable PROMPT would have conflicted with cmd.exe's use of the same name and would have meant a nonsense prompt string any time either command processor was invoked by other. Page 168 Compatibility 7. The following startup or other files have been renamed to be more consistent with OS/2 and NT filename conventions: ~/.cshrc as ~\startup.csh; ~/.login as ~\login.csh; ~/.logout as ~\logout.csh; and ~/.history as ~\history.csh. The ~\login.csh file is read before, rather than after the ~\startup.csh file. When starting the shell as a new session, very little environmental information may be passed; the login.csh is more usefully the first file read in this situation. When starting a subshell, either from csh.exe or cmd.exe, the environment is presumably already set up. Berkeley Compatibility Mode: Berkeley Compatibility Mode provides fairly strict compatibility with the original BSD C shell. Triggered by trying to run a script that starts with #!/bin/csh or interactively if the shell is invoked with the -B option, it causes the C shell to process statements in a more fully Berkeley-compatible fashion. (Scripts that do not start with #!/bin/csh will still be processed according to Hamilton C shell rules, even if the -B option is used to request Berkeley compatibility interactively.) In compatibility mode: 1. The status variable will reflect the return code from the rightmost stage of a pipeline. The tailstatus variable will be ignored. 2. All the shell variables will be snapshotted and all new variables made local to the thread. 3. Berkeley-style $var[...] indexing notation will be used, where the indexing is by word selection operators (like the :-editing operators) rather than by expression. 4. All variable arrays (except argv) will start with element 1. Accessing element 0 will give a null. 5. $0 or $argv[0] will be the scriptname. $argv will be the rest of the argument vector. The bsdargv variable will be ignored. 6. The # character will not need to be followed by white space to be considered the start of a comment. 7. The patterns in a case test (inside a switch) will be strings and need not be quoted, rather than arbitrary expressions. Also, the switch value is evaluated as a wordlist which may contain variable Page 169 Compatibility or command substitutions and wildcards and then rendered as a string. 8. endif and endsw will be predefined aliases for end (but only when closing an if or switch, respectively). breaksw will be a pre-defined alias for break. 9. ``set foo'' and ``setenv foo'' will set foo to a null string, not dump its value. 10. / and /= will perform integer division. 11. The right operand of the =~ and !~ pattern matching operators will be taken as a word which may contain wildcards. 12. In an expression, a variable name must be preceded by $. If it isn't, it'll be taken as a literal string. These changes should allow most scripts to run without problems. However, there will still be a few differences: 1. The escape character will still be controlled by the escapesym variable (shared across all threads), which defaults to ^, not \. 2. Environmental variables will still be shared. Changing them in a script will change them as seen by the parent. 3. The special meaning of several break statements on one line will not be supported. 4. unset and unsetenv still do not accept patterns. 5. The following commands are not supported: bg, exec, fg, glob, jobs, limit, nice (but eval gives similar functionality), nohup, notify, stop, suspend, unlimit and %job. 6. History references inside alias definitions will still not be supported. Page 170 Compatibility Page 171 Language Reference Language Reference Basic Statements: Same as cmd.exe: a file reference + arguments. Examples: cl -AS -G2 -Zi hello.c cp hello.exe c:\os2\bin Hamilton C shell maintains a hash structure which allows it to quickly search for a suitable .csh, .exe, .com, .cmd or (on OS/2 2.0 or NT) .bat file (in that order) in each of as many as 256 path directories. Wildcarding is done by the shell before invoking the child. Under OS/2, up to 64K of environmental and 64K of command-line argument data can be passed to a child process; under NT, up to 32K of command-line data can be passed. These are the limits of the kernels, not the C shell; there is no limit on overall command line length in the C shell itself. Condition-Testing: Hamilton C shell provides both if and switch constructs. The if statement comes in both short and long forms. The long form uses a then keyword and allows an optional else clause. The short form, which must be typed on one line, dispenses with the then keyword and accepts a single statement to be executed if the condition is satisfied. if ( <expr> ) then <statement_list> else <statement_list> end if ( <expr> ) then <statement_list> end if ( <expr> ) <statement> Where an expression is expected, a conventional high level language syntax is accepted: e.g., names Page 172 refer to variables, `*' means multiply, not wildcard and `>' means greater than, not i/o redirection. Page 173 Language Reference if statements can also be chained using the elif keyword. The last if in the chain may be either a short- or a long-form if statement. if ( <expr> ) then <statement_list> elif ( <expr> ) then <statement_list> else <statement_list> end if ( <expr> ) then <statement_list> elif ( <expr> ) then <statement_list> end if ( <expr> ) then <statement_list> elif ( <expr> ) <statement> In a switch statement, expressions are compared by pattern match: the case expression can be a string with wildcard characters. Comparisons are made down the list of alternatives until one matches. All following statements are executed until a break is encountered. A default clause is optional but is always satisfied if no other case matches. switch ( <expr> ) case <expr> : <statement_list> case <expr> : <statement_list> default : <statement_list> end Page 174 Iteration: foreach <name> ( <word list> ) <statement_list> end for <name> = <expr> [ to <expr> ] [ by <expr> ] do <statement_list> end while ( <expr> ) <statement_list> end repeat <number> <statement> repeat <statement_list> until ( <expr> ) The foreach statement is intended for iteration over a list of words, often specified by wildcarding. The for statement offers the more conventional numeric iteration. Multiple iteration ranges, separated by commas, can be specified on the for statement. Procedures: proc <name> ( [ <namelist> ] ) <statement_list> return [ <expr> ] end proc unproc <namelist> Procedures defined by the proc statement can recursively call other procedures. They can be referred to inside an expression or as a new command, in which case any value returned is written to stdout. The proc statement with no arguments causes a list of the available procedures to be written. The unproc statement allows a procedure to be discarded. Page 175 Language Reference Aliases: alias <name> [ = ] ( <word list> ) alias <name> [ = ] <word list> alias alias <name> unalias <namelist> Aliases can be referred to at the beginning of a command and provide a quick, user-defined shorthand. alias <name> with no arguments prints the value of the name. alias without any arguments prints the values of all aliases. Variable and Expression Manipulation: @ <expr> calc <expr> The @ and calc statements will each calculate the value of an expression; the @ statement does it silently while the calc statement writes the result to stdout. set <named_ref> [ = ] ( <word list> ) set <named_ref> [ = ] <word list> setenv <named_ref> [ = ] ( <word list> ) setenv <named_ref> [ = ] <word list> shift [ <name> ] set set <name> setenv setenv <name> unset <namelist> unsetenv <namelist> The set, setenv and shift statements manipulate variables as words rather than expressions. set defines a set variable that's shared between all threads in the shell; setenv puts it into the environment and inherited by child processes. set or setenv with no operands prints a list of all defined variables of that type. set <name> or setenv <name> with no arguments print the value of Page 176 the named variable. unset or unsetenv let you discard a variable. Page 177 Language Reference Local Variables: The local command lets you define a list of variable names that you don't to share with other routines or other processes or threads (except your own child threads). When you define a local variable it hides any previous definition from any outer statement list. (But you are not permitted to redefine any of the built-in set or setenv variable names.) local <namelist> local The <namelist> should be typed with commas between the names. When you create a new local variable, its initial value is always a null string. Typing local with no operands reports the currently defined and accessible local variables, if any. When you spawn a child thread either implicitly, e.g., to run the second or following stage of a pipeline or explicitly, by typing an ampersand at the end of a command to run it in the background all your current local variables are snapshotted and copied to the child. If, following that, either the parent or the child changes the value of any of these local variables, it affects only its own copy. Local variables are automatically discarded as soon as execution leaves the statement nesting level in which the variable was created. You can also explicitly discard local variables using the unlocal command. unlocal <namelist> In all other respects, local variables act just like any other variables, though you may find they're slightly faster since the shell doesn't need to semaphore its use of them. Page 178 Function Keys setkey command: The setkey command lets you define a list of words that should be stuffed back onto the command-line whenever you press a particular function key. The syntax is exactly the same as used in the set, setenv and alias commands: setkey <fkey> [ = ] ( <word list> ) setkey <fkey> [ = ] <word list> where <fkey> is any of the function keys f1 (or F1) through f12 (or F12.) Typing setkey with no operands reports the current function key bindings, if any. Also, a corresponding unsetkey command lets you discard key bindings: setkey unsetkey <fkeylist> The <fkeylist> should be typed with commas between the keys. For example: unsetkey f1, f2 Using the Function Keys Key Meaning <Fx> Clear the command line, post the text bound to this key and execute the command. Alt-<Fx> Insert the text bound to this key at the cursor location but don't execute it yet. Ctrl-<Fx> Clear the command line and post the text bound to this key but don't execute it yet. Page 179 Language Reference Since the function key's bound text is written back into the command line inside command line editor, the substitution happens ahead of any parsing of the command line into words or expansion of history ``!...'' or ``%...'' references so it is possible to meaningfully embed these kinds of references into the key binding. Page 180 Miscellaneous Statements Statement Function <drive>: Change current drive. <label>: <statement> Define a label. ( <statement_list> ) Group a list of statements, saving and restoring the current directory during execution break [ <name> ] Exit from the named or, by default, the innermost switch, foreach, for, while or repeat statement. continue [ <name> ] Continue with the next iteration of the named or innermost foreach, for, while or repeat. exit [ <expr> ] Exit from this thread or, if this is the main thread, from the C shell. goto <name> Continue at the labeled statement. onintr <statement> Define the action to be taken if an interrupt is signaled. Whatever's running is interrupted all the way back up to the block in which the onintr was defined. That statement is run in the current thread and execution continues with the next statement in the block where the onintr was defined. When execution leaves a block in which an onintr is defined, the previous onintr (if any) again takes effect. To ignore or defer interrupts, use the irqmask variable. Page 181 Language Reference source <wordargs> Read and process statements from a file as if they were typed into this thread. time <statement> Execute the statement and report how long it took. # Comment text up to the end of the line. (To be recognized as a valid comment, the # must be followed by at least one space or tab.) Page 182 Statement Relationships In order of decreasing precedence: Operator Meaning ( ) Grouping > >! >& >&! >> >>! >>& >>&! < << I/O Redirection | |& Piping (stdout only or stdout + stderr) between concurrent operations ... & Background thread or process && || Conditional execution: only if first succeeds or only if first fails ; Serial execution I/O Redirection Operator Meaning > >! >& >&! Output to a file (`!' allows an existing file to be overwritten; `&' redirects both stdout and stderr.) >> >>! >>& >>&! Append to a file < In from a file << <string> Inline data: the text on the following lines, up to the line containing only the specified <string> will be fed as stdin to the statement. Unless part of <string> is escaped or Page 183 Language Reference single, double or backquoted, command and variable substitution will be done on the inline text. The grammar is completely recursive, so statements of arbitrary complexity can be freely nested, conditionally executed, piped or redirected. Page 184 Expression Operators In order of decreasing precedence: Operator Meaning ( ) Grouping or Procedure call arguments { } Run the enclosed statement list and return 1 if it succeeds or 0 otherwise. [ ] Array indexing. (The first element is element 0.) -A -D -H -R -S -d -e -f -o -w -x -z File system tests ++ -- Prefix and postfix increment/decrement ~ - ! + Bitwise, arithmetic and logical complements and unary plus ** Exponentiation * / % // Multiplication, Division, Remainder and Integer Division + - Addition and Subtraction << >> Bit Shifting == != =~ !~ < <= >= > Relation- testing and pattern-matching operators & Bit And ^ Bit Xor | Bit Or && Logical And || Logical Or ?: Conditional selection Page 185 Language Reference = += -= *= /= %= //= >>= <<= &= ^= |= **= Assignment operators Expressions result in sensible types, considering both the types and the values of the operands. For example, 10/2 returns the integer 5 but 5/2 produces the floating point value 2.5. Also, the integer 1, the floating point value 1.0 and the string ``1'' all compare equal. Page 186 File System Tests The operand of a file system test is interpreted as a word, not an expression, and may involve wildcarding. If wildcarding produces more than one match, the test is done on the first one. Prefix Operator True if -A Archive Bit Set -D -d Directory -H Hidden File or Directory -R Read-only File or Directory -S System File or Directory -e File or Directory Exists -f Ordinary File -o Ownership (Same as Existence on an OS/2 or NT FAT file system) -r Readable (Same as ordinary file on an OS/2 or NT FAT file system) -w Writable (Not Read-only and not a directory) -x Executable (Has a .csh, .exe, .com or .cmd extension and, if it's an .exe or a .com file, appears to be a valid OS/2 or NT binary executable.) -z Zero-length File Example: if (-d $a) then echo $a is a directory end Page 187 Language Reference Special Devices Name Use aux+ The auxiliary port. clock$+ The OS/2 system clock. con The OS/2 console. This is the text window the shell is running in. Reading from it reads the keyboard; writing to it writes to the screen. conin$ The NT console keyboard. A read- only device. conout$ The NT console display. A write- only device. com1 .. com7 The various async communication ports you may have. They can be read or written. kbd$ The OS/2 keyboard. A read-only device. lpt1 .. lpt4+ The line printer ports. nul The null device. Reads return end- of-file; writes are discarded. prn The print spooler queue. pointer$+ The OS/2 mouse and on-screen pointer combination. Reads from the mouse; writes to the screen. screen$ The OS/2 text window. A write-only device. Hamilton C shell recognizes the OS/2 and NT special device names regardless of whether they are typed in upper or lower case and regardless of whether there is a trailing colon. For example, COM1: is the same as COM1 is the same as com1. Remember to quote the device name if it has a dollar sign at the end so it won't be misinterpreted as the start of a variable reference. Page 188 Not all devices will be installed on any particular machine. Also, the exact behavior of any device may depend which manufacturer supplied it. Devices marked with + should only be accessed with some caution. Page 189 Language Reference Wildcarding and Pattern Matching Characters Meaning ? Match any single character, including `.' but not `\' or '/'. * Match any number of characters, including `.' but not '\' or '/'. [a-z] An example range: match any character a through z. [^a-z] An example exclusion range: match any character not in the set a through z. {a,b}c Alternation: generate both ac and bc. ... Indefinite Directory: match any number of directory levels -- zero or more -- whatever it takes to make the rest of the pattern match. Patterns are used both for traditional filename wildcarding in word mode and for examining strings in expression mode. Patterns are nestable arbitrarily and a recursive comparison algorithm is used to guarantee a sensible result no matter how complex the pattern. For example: *r* or even *\[a-c]*.[ch] operate sensibly. Filename wildcards can be used wherever a word is expected and will match any filename except ``.'' and ``..'' unless it's marked ``hidden.'' (To allow wildcarding to match hidden files, set nonohidden = 1.) Quoting the word prevents wildcarding. Since filenames are not case sensitive, filename wildcarding isn't either. A pattern can also be used to examine a string in a switch statement or with the ``=~'' (pattern matches) and ``!~'' (pattern fails) expression operators. In this context, the pattern must be inside quotes, since otherwise it would be parsed as an expression, with ``*'' being viewed as the multiply operator, etc. When examining a string with a pattern that uses alternation, the pattern Page 190 ``matches'' if any of the alternatives matches. When matching strings, case does matter. When using a pattern to examine a string with ``=~'' or ``!~'' or with a switch, the string being tested is the left operand and the pattern is on the right. Page 191 Language Reference Filename Completion Filename completion lets you type just the first part of a filename and have the shell fill in the rest. The two variations are using the F key for basic filename completion or the D key if you want all the duplicates listed. Key Meaning Alt-F or Ctrl-F Filename completion. Appending the ``*'' wildcard character onto the end, use the previous word as a wildcard pattern. If it matches a single file, substitute it in with a space following. (If you don't want a space following, use the -N option when you start the C shell.) If there were multiple matches, but they all had some common front-part that fully ``used up'' the pattern, substitute in just that common front- part and show it in the color specified by the DUPLICATES variable (default is green). If substitution wasn't possible, highlight the pattern in the color specified by the MATCHFAIL variable (default is bright red). (Any highlighting color is turned off when you press the next keystroke.) Alt-D or Ctrl-D Duplicate completions. Same wildcarding, but if there are multiple matches, show them all with a space following. (Here again, if you don't want a space following, use the -N option when you start the C shell.) If there were no matches, highlight the pattern in the color specified by the MATCHFAIL variable (default is bright red). Page 192 Command Line Editing Key Meaning Page 193 Language Reference <Enter> Accept the command as typed. Move to the end (if not there already) and carriage return to a new line. <Home> Beginning of command line. <End> End of command line. <Up> Up one command in the history list. Each time it's pressed, it displays the preceding entry in the history list. Any ``!...'' or ``%...'' history references in the original text will have been fixed up unless it was the immediately preceding command and it had one these references that failed. If already at the first entry, the command line is highlighted in bright red. <Down> Down one command line in the history list. If already at the latest entry, the command line is highlighted in bright red. <Left> One character left. <Right> One character right. Ctrl-<Home> Move to the upper-leftmost character in the current screenful if the command is long enough that it actually wraps across several screens. Ctrl-<End> Move to the lower-rightmost character in the current screenful. Ctrl-<Up> Up one row on the screen if the command is long enough that it runs over a row. Ctrl-<Down> Down one row on the screen. Ctrl-<Left> Backup word. Ctrl-<Right> Forward word. Alt-<Home> Delete all preceding characters on the command line. Alt-<End> Delete all following characters. Alt-<Up> Delete up one row on the screen if the command runs over a row. Alt-<Down> Delete down one row. Alt-<Left> Delete preceding word. Ctrl-<Backspace> Alt-<Right> Delete following word. <Insert> Toggle insert/overstrike mode. When inserting, the cursor is slightly thicker. Ctrl-<Insert> Insert the next word from the last section of deleted text. When it reaches the end of the deleted text, it starts over. Alt-<Insert> Insert all the rest of the previously deleted text. <PageUp> Backup to one past the last history reference. (Repeatedly typing <PageUp> <Enter> is a convenient way of picking up a whole series of commands from history.) <PageDown> Forward to the newest entry in the history list. Page 194 <Esc> Clear the command line. Note: Users lacking separate arrow keys must press Ctrl-Shift instead of Alt. Page 195 Language Reference History Recall Command Meaning !! Last command !^ First argument word of last command !$ Last word of last command !* All arguments of last command !n Command n !-n nth command from the last !str Last command starting with str !?str? Last command containing str %str1%str2% Substitute str2 for str1 in last command. (Used only at the beginning of a line.) History recall allows a previous statement to be quickly recalled and re-executed. It's a very fast shorthand, especially in the edit/compile/debug loop or to fix a typo. For convenience, ``!'' is taken as an ordinary character if followed by white space, ``='', ``~'' or ``(''. If you want, you can choose different characters to introduce history references by changing the histchars variable. Command Completion Command completion lets you type just part of a previous command and have the shell fill in the rest. As with filename completion, if no match is found, color highlighting as defined by the MATCHFAIL variable (default is bright red) will be used. Consecutive depressions cause the search to continue on back through the history list. Key Meaning Page 196 Ctrl-<Enter> Search for the last command that starts with the characters in the previous word. Alt-<Enter> Search for the last command that contains the characters in the previous word anywhere on the command line. Page 197 Language Reference Quoting String Meaning '...' Literal character string. Only do history substitutions. "..." Single word. Typically used if there are embedded blanks or wildcard characters you want treated as ordinary. Has no effect on command or variable substitutions: they're still done. `...` Command substitution. Evaluate the string as a separate command and substitute its output back onto the command line. Newlines are turned into spaces and Ansi escape sequences (for highlighting, etc.) are filtered out. ^ Quote just the next character. Use to remove any special meaning from the next character, to specify a character by its binary value or to specify one following non-printable characters. If the NewLine character at the end of a line is quoted this way, it's treated as ordinary white space. (You can choose a different escape character by changing the escapesym variable.) Escape Sequences String Meaning ^a Audible alert (bell) ^b Backspace ^f Form Feed ^n New Line ^r Carriage Return ^t Tab ^v Vertical Tab Page 198 ^^ Single escapesym character Page 199 Language Reference Variable Substitution Reference Meaning $var ${var} value of variable var $var[<expr>] ${var[<expr>]} value of var, indexed by an arbitrarily complex expression $#var ${#var} Number of words in var $?var ${?var} 1 if var exists; 0 otherwise $procname( <argument list> ) Procedure reference, used as a variable substitution. The arguments are expressions, separated by commas. Any value returned by the procedure will be substituted in place. $< Pseudo-variable result of reading one line from stdin each time it's evaluated $0 .. $9 Same as $argv[0] .. $argv[9] Variable substitution is typically used to pass the value of a variable as an argument to a command. For example: cl -AS -G2 -Zi $a.c Page 200 Substitution Modifiers Operator Meaning :n nth word :# Count the number of words :^ Word number 1, counting from 0 :$ Last word :% Word matched by a !?str? history search :n-m nth through mth words :-n 0 through nth words :n- n through next-to-last words :n* n through last word :* 1 through last word :q Single quote each word :s/str1/str2/ Substitute str2 for str1 and then reparse into words. Match failures are considered to be errors unless ignoreerrors == 2. :S/str1/str2/ Substitute str2 for str1 but leave it as a single string. Also, failure to match is not considered an error. :& Repeat last substitution :g... Global editing: apply the edit operation everywhere it matches, not just the first occurrence. :x Treat each word as a string and break it up into words Page 201 Language Reference :p Print the substitution but don't execute the statement. (Ignored except in history substitutions.) Substitution modifiers can be applied to any command, variable or history substitution. Also, any number in a row can be applied, as desired. Page 202 Pathname Editing on x\y\z.c Operator Name Description Result :h head Directory containing x\y :r root Path w/o .ext x\y\z :t tail Simple filename z.c :b base Filename w/o .ext z :e ext .ext w/o the ``.'' c :f fullpath Fully-qualified name d:\bob\x\y\z .c Pathname editing can be applied to any command, variable or history substitution. Also, any number of pathname editing operations can be applied, one after the other, to a given substitution. Example: echo $path:gt Page 203 Language Reference Page 204 Environmental Variables Recognized Name Default Use ADDITIONSBright Green Lines added found by diff. CDPATH List of directories to search for the subdirectory specified as the new current directory. COLORS White on Black Normal screen colors. COMSPEC Usually, this is the pathname of cmd.exe. If you set it to point to the C shell, e.g., so other programs will invoke the C shell rather than cmd.exe, the C shell will try to look through the search path for cmd.exe if it needs to run a .cmd file. CSHOPTIONS Default set of command line options to be pasted ahead of any other command line options passed to csh.exe. DELETIONS Bright Red Lines deleted found by diff. DIRECTORIES Bright Directories listed by ls. DRIVEMASK Used by du.exe, pwd.exe and vl.exe to limit the default list of drives it will report on. Written as a list of alphabetic characters representing the drives you want listed; ranges are allowed. If you don't define this variable, all drives beginning with C: are normally reported. DUPLICATES Green When filename completion matches matches more than one name. ESCAPESYM ^ Character to be interpreted as a literal escape character. Placed in the environment only if it is not the default circumflex. FOREIGNFILESBright Red Filetypes in a tar file that have no counterpart on OS/2. HIGHLIGHT Bright Current disk or directory. Page 205 Predefined Variables HOME Home directory (default is the initial current directory.) LSOPTIONS Default set of command line options to be pasted ahead of any other command line options passed to ls.exe. MATCHFAIL Bright Red When filename or command completion doesn't match anything. Page 206 Environmental Variables Recognized Name Default Use MIXEDCASEDRIVES List of drives for which ls.exe, pwd.exe, wildcarding and the current directory functions should report filenames in mixed case rather than all lower case. MOREEOF Green End or Top of File in more. MOREERRORBright Yellow Unrecognizable command to more. MOREFILLIN White User response to more prompt. MOREPROMPT Green Prompt line in more. MORETOPMEMBright Yellow Top of Memory message from more. NETWORKBUG If NETWORKBUG = 1, the shell and all the utilities will read directory entries only one-at-a- time as a workaround for a networking bug. (Not used on NT.) PATH Search path for executable files. PROMPT1 $@ $CDISK% Primary command prompt template. PROMPT2 $@ $CDISK? Continuation line prompt template. RADIX 16 Default radix used by more.exe and other utilities when displaying binary data. SHELL Always set to the pathname of the Hamilton C shell csh.exe file. SWITCHCHARS -/ Characters that can be used as option introducers for the shell and utilities. SYSTEMDIRSBright Green Used by ls.exe for directories with the System bit on. SYSTEMFILES Green Used by ls.exe for files with the System bit on. TABS 8 Used by more.exe, head.exe, tail.exe and tabs.exe to tell them Page 207 Predefined Variables how many character positions there are between tab stops. Page 208 Environmental Variables Recognized Name Default Use TZ Used by tar.exe under OS/2 to tell it how to convert between local time and GMT. (Under Windows NT, the system keeps track of the difference between local time and GMT, so the TZ variable is not needed.) The TZ variable should be of the form of a three-letter timezone, e.g., EST, followed by a signed number giving the difference in hours between GMT and local time, followed by an optional daylight savings timezone. Examples are EST5EDT in New York or PST8PDT in California. Environmental variables are passed to any child processes or screens you create by invoking an external utility or application. When Hamilton C shell starts up it looks for the ones shown here to be defined in the environment it inherits. HOME, PATH and SHELL are special: if they're not already defined, then the shell creates them. On Windows NT, environmental variables are not case- sensitive, so, e.g., Path and PATH refer to the same thing. Page 209 Predefined Variables Predefined Process-Wide Variables Name Default Use $ A synonym for the processid variable. bsdhistory 0 By default, ``!!'' is the immediately preceding command and ``!-1'' is the one before that. Setting bsdhistory = 1 makes them the same. cdpath null Same as the CDPATH environmental variable, broken into words. escapesym ^ Character to be interpreted as a literal escape character. histchars !% Characters which introduce long- form and short-form history references, respectively. home Same as the HOME environmental variable. NTVersion Build number of the NT system on which the shell is running, e.g., 340 for the October Beta. (Not defined on OS/2.) os2version Version number of the OS/2 system on which the shell is running. (Not defined on NT.) path Same as the PATH environmental variable, broken into words. processid The unique process ID assigned by the OS/2 or NT kernel to this copy of the C shell. prompt1 $@ $CDISK% Same as PROMPT1 environmental variable. prompt2 $@ $CDISK? Same as PROMPT2 environmental variable. Page 210 savehist 0 Save the history contents into history.csh in the home directory. shell Same as SHELL environmental variable. WinVersion Version number of the Windows API on which the shell is running, e.g., 3.1 for the October Beta. (Not defined on OS/2.) Any user-defined variables (with the exception of the parameter names of a procedure or those variables explicitly defined as local) are shared globally by all threads. Page 211 Predefined Variables Predefined Per-Thread Variables Inherited from the parent thread: Name Default Use argv Any argument words passed to the shell or to a .csh batch file. bsdargv 0 If set, $argv[0] contains the name of the script, just as it would under the original Berkeley C shell; by default, $argv[0] is the first argument word. cdhome 0 If set, ``cd'' with no argument is the same as ``cd $home''; default is to simply print the current directory name. cdisk Current disk, not including colon. CDISK Same as cdisk, but in upper case. chgdisk 0 If set, cd automatically does a DosSelectDisk if the path is on another disk. cwd Full pathname of the current directory. gotowindow 50 Number of statements a goto can jump over (when not inside a nested block) without being considered an error. nohashing 0 Determine how/whether path hashing is done: 0 means full path hashing of the directories on the search path; 1 means turn off hashing completely; 2 means hash only the directories which do not depend on the setting of the current directory. noclobber 0 If True, don't allow redirection to overwrite an existing file unless the ``!'' override is given. Page 212 noglob A synonym for the nowild variable. nonohidden 0 Determine whether wildcarding will match against hidden files: 0 means don't match hidden files; 1 means hidden files will be found. nonomatch 0 Determine the response to a wildcard that doesn't match anything: 0 means it's an error; 1 means pass it through to the application; 2 means simply discard it. Page 213 Predefined Variables Predefined Per-Thread Variables Inherited from the parent thread: Name Default Use nonovar 0 Determine the response to a reference to a non-existent variable, procedure or alias. Same encoding as nonomatch. nowild 0 If True, turn off filename wildcarding. nullwords 0 Determines whether an array index off the end of a list is an error (0) or returns a null word (1). precision 6 Number of decimal places to print when displaying floating point values. tailstatus 0 Determines whether the status variable will reflect the reflect the return code from the leftmost or rightmost stage of a pipeline: 0 means leftmost; 1 means rightmost. verbose 0 If True, print out all available information when reporting errors. Each new thread is initialized with default on- interrupt processing (a forced exit), and null search and replace strings. echoinput, ignoreerrors and interactive are initialized for the main thread based on command-line options. Each thread also has its own independent notion of current disk and current directories, initially inherited from its parent. Page 214 Predefined Per-Thread Variables Always initialized to the default for each new child thread: Name Default Use * A synonym for the argv variable. < A synonym for the getline variable. @ A synonym for the stmtnumber variable. child 0 Identification number of the last child process spawned. echoinput 0 Copy the input to stdout as it's read. eofgetline 0 Pseudo-variable to indicate if the last reference to getline encountered an end-of-file condition. getchar Read one character from stdin without echoing. If stdin is tied to the keyboard, outboard keys are returned as a two-character string. getline Read one line from stdin pseudo- variable. If stdin is tied to the keyboard, keystrokes are echoed as they're typed. history 0 Number of statements to remember on the history list; 0 turns off the history mechanism. (If the thread is interactive, history is automatically set to 100.) ignoreeof 0 If True, don't exit at EOF on stdin; insist on an exit command. ignoreerrors 0 Determine whether execution should continue if an error occurs: 0 means the thread exits; 1 (the default for an interactive thread) means exit from loops or procedures and try to read a new Page 215 Predefined Variables command; 2 means ignore all errors. ignorestatus 1 If True, a non-zero status code from a child process is ignored. Otherwise, it's an error. interactive 0 If True, prompt for input. irqmask 0 Determines whether interrupts are enabled (0), deferred until the mask is cleared again (1) or ignored (2). scriptname Name of the C shell script file being executed, if any. Page 216 Predefined Per-Thread Variables Always initialized to the default for each new child thread: Name Default Use status 0 Exit code of the last child process. stmtnumber 1 Autoincremented statement number used with the history list and in prompting. threadid Thread id of the currently executing thread. Page 217 Predefined Variables Predefined Variables Sorted by Name Legend for this table: COURIER A setenv environmental variable. Environmental variables are passed to any child processes or screens you create by invoking an external utility or application. When Hamilton C shell starts up it looks for the ones shown here to be defined in the environment it inherits; if they're not already defined, the shell creates them. bold A set variable shared by all threads: if one makes a change, all will see it. normal Each thread gets its own copy but the initial value is inherited from its parent. italics Each thread gets its own copy but the initialization is always to a defined value. Name Default Use $ A synonym for the processid variable. * A synonym for the argv variable. < A synonym for the getline variable. @ A synonym for the stmtnumber variable. ADDITIONSBright Green Lines added found by diff. argv Any argument words passed to the shell or to a .csh batch file. bsdargv 0 If set, $argv[0] contains the name of the script, just as it would under the original Berkeley C shell; by default, $argv[0] is the first argument word. bsdhistory 0 By default, ``!!'' is the immediately preceding command and ``!-1'' is the one before that. Page 218 Setting bsdhistory = 1 makes them the same. cdhome 0 If set, ``cd'' with no argument is the same as ``cd $home''; default is to simply print the current directory name. cdisk Current disk, not including colon. CDISK Same as cdisk, but in upper case. CDPATH List of directories to search for the subdirectory specified as the new current directory. Page 219 Predefined Variables Predefined Variables Sorted by Name Name Default Use cdpath null Same as the CDPATH environmental variable, broken into words. chgdisk 0 If set, cd automatically does a DosSelectDisk if the path is on another disk. child 0 Identification number of the last child process spawned. COLORS White on Black Normal screen colors. COMSPEC Usually, this is the pathname of cmd.exe. If you set it to point to the C shell, e.g., so other programs will invoke the C shell rather than cmd.exe, the C shell will try to look through the search path for cmd.exe if it needs to run a .cmd file. CSHOPTIONS Default set of command line options to be pasted ahead of any other command line options passed to csh.exe. cwd Full pathname of the current directory. DELETIONS Bright Red Lines deleted found by diff. DIRECTORIES Bright Directories listed by ls. DUPLICATES Green When filename completion matches matches more than one name. DRIVEMASK Used by du.exe, pwd.exe and vl.exe to limit the default list of drives it will report on. Written as a list of alphabetic characters representing the drives you want listed; ranges are allowed. If you don't define this variable, all drives beginning with C: are normally reported. Page 220 echoinput 0 Copy the input to stdout as it's read. eofgetline 0 Pseudo-variable to indicate if the last reference to getline encountered an end-of-file condition. ESCAPESYM ^ Character to be interpreted as a literal escape character. Placed in the environment only if it is not the default circumflex. Page 221 Predefined Variables Predefined Variables Sorted by Name Name Default Use escapesym ^ Same as the ESCAPESYM environmental variable. FOREIGNFILESBright Red Filetypes in a tar file that have no counterpart on OS/2 or NT. getchar Read one character from stdin without echoing. If stdin is tied to the keyboard, outboard keys are returned as a two-character string. getline Read one line from stdin pseudo- variable. If stdin is tied to the keyboard, keystrokes are echoed as they're typed. gotowindow 50 Number of statements a goto can jump over (when not inside a nested block) without being considered an error. HIGHLIGHT Bright Current disk or directory. histchars !% Characters which introduce long- form and short-form history references, respectively. history 0 Number of statements to remember on the history list; 0 turns off the history mechanism. (If the thread is interactive, history is automatically set to 100.) HOME Home directory (default is the initial current directory.) home Same as the HOME environmental variable. ignoreeof 0 If True, don't exit at EOF on stdin; insist on an exit command. ignoreerrors 0 Determine whether execution should continue if an error occurs: 0 means the thread exits; 1 (the Page 222 default for an interactive thread) means exit from loops or procedures and try to read a new command; 2 means ignore all errors. ignorestatus 1 If True, a non-zero status code from a child process is ignored. Otherwise, it's an error. interactive 0 If True, prompt for input. Page 223 Predefined Variables Predefined Variables Sorted by Name Name Default Use irqmask 0 Determines whether interrupts are enabled (0), deferred until the mask is cleared again (1) or ignored (2). LSOPTIONS Default set of command line options to be pasted ahead of any other command line options passed to ls.exe. MATCHFAIL Bright Red When filename or command completion doesn't match anything. MIXEDCASEDRIVES List of drives for which ls.exe, pwd.exe, wildcarding and the current directory functions should report filenames in mixed case rather than all lower case. MOREEOF Green End or Top of File in more. MOREERRORBright Yellow Unrecognizable command to more. MOREFILLIN White User response to more prompt. MOREPROMPT Green Prompt line in more. MORETOPMEMBright Yellow Top of Memory message from more. NETWORKBUG If NETWORKBUG = 1, the shell and all the utilities will read directory entries only one-at-a- time as a workaround for a networking bug. (Not used on NT.) nohashing 0 Determine how/whether path hashing is done: 0 means full path hashing of the directories on the search path; 1 means turn off hashing completely; 2 means hash only the directories which do not depend on the setting of the current directory. Page 224 noclobber 0 If True, don't allow redirection to overwrite an existing file unless the ``!'' override is given. noglob A synonym for the nowild variable. nonohidden 0 Determine whether wildcarding will match against hidden files: 0 means don't match hidden files; 1 means hidden files will be found. Page 225 Predefined Variables Predefined Variables Sorted by Name Name Default Use nonomatch 0 Determine the response to a wildcard that doesn't match anything: 0 means it's an error; 1 means pass it through to the application; 2 means simply discard it. nonovar 0 Determine the response to a non- existent variable, procedure or alias. Same encoding as nonomatch. nowild 0 If True, turn off filename wildcarding. NTVersion Build number of the NT system on which the shell is running, e.g., 340 for the October Beta. (Not defined on OS/2.) nullwords 0 Determines whether an array index off the end of a list is an error (0) or returns a null word (1). os2version Version number of the OS/2 system on which the shell is running. (Not defined on NT.) PATH Search path for executable files. path Same as the PATH environmental variable, broken into words. precision 6 Number of decimal places to print when displaying floating point values. processid The unique process ID assigned by the OS/2 or NT kernel to this copy of the C shell. PROMPT1 $@ $CDISK% Primary command prompt template. prompt1 Same as the PROMPT1 environmental variable. Page 226 PROMPT2 $@ $CDISK? Continuation line prompt template. prompt2 Same as the PROMPT2 environmental variable. RADIX 16 Default radix used by more.exe when displaying binary data. savehist 0 Save the history contents into history.csh in the home directory. scriptname Name of the C shell script file being executed, if any. SHELL Always set to the pathname of the Hamilton C shell csh.exe file. Page 227 Predefined Variables Predefined Variables Sorted by Name Name Default Use shell Same as the SHELL environmental variable. status 0 Exit code of the last child process. stmtnumber 1 Autoincremented statement number used with the history list and in prompting. SWITCHCHARS -/ Characters that can be used as option introducers for the shell and utilities. SYSTEMDIRSBright Green Used by ls.exe for directories with the System bit on. SYSTEMFILES Green Used by ls.exe for files with the System bit on. TABS 8 Used by more.exe to tell it how many character positions there are between tab stops. tailstatus 0 Determines whether the status variable will reflect the reflect the return code from the leftmost or rightmost stage of a pipeline: 0 means leftmost; 1 means rightmost. threadid Thread id of the currently executing thread. TZ Used by tar.exe under OS/2 to tell it how to convert between local time and GMT. (Under Windows NT, the system keeps track of the difference between local time and GMT, so the TZ variable is not needed.) The TZ variable should be in the form of a three-letter timezone, e.g., EST, followed by a signed number giving the difference in hours between GMT and local time, followed by an Page 228 optional daylight savings timezone. Examples are EST5EDT in New York or PST8PDT in California. verbose 0 If True, print out all available information when reporting errors. WinVersion Version number of the Windows API on which the shell is running, e.g., 3.1 for the October Beta. (Not defined on OS/2.) Page 229 Built-in Procedures Built-in Procedures Name Function Filename Functions: childpath(p, c) Test whether filename c could be in a subdirectory of p. (Does not test for actual existence of either c or p.) driveno(p) Drive number implied by pathname p. fullpath(p) Fully resolve pathname p. samepath(a, b) Test whether two filenames, a and b, point to the same file. Math Functions: abs(x) Absolute value acos(x) asin(x) atan(x) cos(x) sin(x) tan(x) Trigonometric functions cosh(x) sinh(x) tanh(x) Hyperbolic functions ceil(x) Ceiling (lowest integer >= x) exp(x) log(x) log2(x) log10(x) Exponential and logarithmic functions floor(x) Floor (highest integer <= x) round(x) floor(x + 0.5) sqrt(x) Square root Page 230 Built-in Procedures Built-in Procedures Name Function String Functions: ansi(color) Return an ANSI escape sequence which will produce the specified screen colors. If the argument is ambiguous, e.g., simply ``bright,'' it's taken as a modification of the default colors specified by the COLORS variable. char(i) Return the character corresponding to the numeric value i. code(c) Return the numeric encoding of the character c. concat(a, b, ...) Concatenation of a series of strings. isinteger(x) Test whether x is an integer. (Remember that null strings and strings consisting only of white space are considered equal to 0.) isnumber(x) Test whether x is a number. printf(fmt, ...) Perform C language-style print formatting, returning the result as a string. (See table of format conversions on following page.) reverse(s) Reverse the order of characters in s. strindex(a, b) Return the position in a of the first occurrence of b. (0 means b was not found.) strlen(s) Number of characters in s, represented as a string Page 231 Built-in Procedures substr(s, b, i) Substring of length i beginning at b-th character of s. (i = 0 means ``rest of s'') upper(s) lower(s) Translate a string to all upper- or all lower-case Page 232 Built-in Procedures Printf Format Directives These argument formats are recognized by printf: %c Single character. %d Decimal number. %e [-]d.dddddde[+-]ddd %f [-]ddd.dddddd %g %e or %f formatting, whichever is shorter. %o Unsigned octal number. %s String. %x unsigned hexadecimal number. %% Literal % character. Additional parameters may lie between the % and the control letter: - Left-justify expression in its field. width Pad field to this width as needed; leading 0 pads with zeros. .prec Maximum string width or digits to right of decimal point. Page 233 Built-in Procedures Page 234 Utilities Built-in Utilities Command Function cd Change working directory. Optionally, change disk. chcp Change code page. (Not implemented on NT.) chdir A synonym for cd. cls Clear the screen. dirs Print the directory stack. echo Echo arguments to stdout. eval Defer parsing of the word list until the evaluation phase. hashstat Print path hash statistics. heapstat Print heap usage statistics. history Display the history list. kill Kill background activity. popd Pop directory stack. ps List process and thread status. pushd Push a new current directory on the directory stack or exchange the top two items. rehash Rehash the path directories. rotd Rotate the directory stack. sleep Sleep for a specified period. source Read commands from a file. Page 235 Utilities unhash Turn off path list hashing. verify Turn on write verification mode. wait Wait for children to complete. All built-in utilities self-document with the -h option. Page 236 Utilities External Utilities Command Function binedit Binary edit. cat Concatenate files. chmod Change mode bits of file. cp Copy files or directories. cut Cut out selected fields of each line of text. des Encrypt or decrypt data using the Data Encryption Standard (DES). date Display the date and time. diff Compare files or directories. dim Discard any ansi escape sequences in the input stream. dskread Read raw sectors from a disk. (Future release on NT.) dskwrite Write raw sectors to a disk. (Future release on NT.) du Display disk usage. fgrep Fast string search (fast grep) of text files. grep Regular expression pattern search of text files. head Copy the first few lines or bytes of a file to stdout. label Read/Write the volume label. Page 237 Utilities ls List directory contents. markexe Mark an .exe file to indicate what sort of application it is. (OS/2 only.) mkdir Make a new directory. more A better more utility. (Able to search forward or backward or to a specific line.) moreh A large model version of more. mv Move files or directories. Page 238 Utilities External Utilities Command Function newer Test whether first file is newer than the others. older Test whether first file is older than the others. patchlnk A (very) special-purpose utility to patch a bug in the Microsoft linker on OS/2. pwd Print the working directories. rm Remove files or directories. rmdir Remove directories. sed Stream editor. setrows Set or report the number of rows in the display window. (OS/2 only.) split Split a large file into equal-sized chunks. strings Extract ASCII strings from a file. sum Checksum the contents of a file. tabs Expand/Unexpand tabs. tail Copy the last few lines or bytes of a file to stdout. tar Read/Write UNIX tape archive (tar) format files. tee Pipe fitting. touch Update the time-stamp on a file. Page 239 Utilities tr Translate characters. uniq Report unique lines in text files. ver Display the current system and Hamilton C shell version numbers. vol Display the disk volume label. wc Count lines, words and characters. whereis Tell which PATH directory a given executable is in. xd Hex dump a file to stdout. Page 240 Utilities All external utilities except whereis self- document with the -h option. Any external utility may be renamed simply by renaming the executable file. Page 241 Popular Aliases Popular Aliases Command Definition Function app cat >> Append to a file. beep eval echo -n ^a Beep sound. breaksw break Older BSD4.3 name for a break statement inside a switch. cdd cd +c Change the directory and disk in one command. copy local s ; @ s = nowild ; @ nowild = 1 ; safecopy Invoke the standard IBM/MS copy command with shell wildcarding turned off so copy will work sensibly. date dt Display the current time and date. del local s ; @ s = nowild ; @ nowild = 1 ; safedel Invoke the del command with shell wildcarding turned off so ``del *.*'' will still produce the ``Are you sure?'' message. di diff -b! Run the diff command, ignoring white space differences and using color to highlight the changes. dir cmd /c dir Invoke the cmd.exe dir command. duc du -c Disk usage for the current disk only. dumphist history -s > ~\history.csh Dump out the history list. endif end Older BSD4.3 name for the end of an if statement. Page 242 Popular Aliases endsw end Older BSD4.3 name for the end of switch statement. erase del Alternate name for del. f fgrep Quicker name for fgrep. fn fgrep -n Fgrep and print line numbers. g grep Quicker name for grep. h history Quicker name for history. Page 243 Popular Aliases Popular Aliases Command Definition Function help helpmsg Invoke the IBM/Microsoft help command. (OS/2 only.) home cdd ~ Change to the home disk and directory. ld ls -a +D -. List only the subdirectories. ll ls -L List directories, long format. loadhist source -n ~\history.csh Load the history list without executing any of it. md mkdir Make directories. mi moreh -i Quick interactive startup of your favorite version more. Clears the screen when it starts up and doesn't just exit if there's less than a screenful. mih moreh -i Huge interactive more. mis more -i Small interactive more. pause echo -n Press any key when ready ... ; @ getchar ; echo Pause, waiting for any keystroke or character from stdin. q exit Exit the C shell rd rmdir Remove empty directories. ren rename Another name for the rename alias. rename local s ; @ s = nowild ; @ nowild = 1 ; saferename Page 244 Popular Aliases Invoke the standard IBM/MS rename command with shell wildcarding turned off so the rename will work sensibly. start cmd /c start Start a new session via the cmd.exe start command. type cat Copy files to stdout. vol vl List volume labels. w (wait; beep) Wait for background processes and beep. Page 245 Popular Aliases Popular Aliases Command Definition Function xcopy local s ; @ s = nowild ; @ nowild = 1 ; safexcopy Invoke the standard IBM/MS xcopy command with shell wildcarding turned off so xcopy will work sensibly. Page 246 Popular Aliases Page 247 Help Help for Hamilton C shell csh: Startup the Hamilton C shell Usage: csh [-!BbefFhHiKLlNnstuXZ-] [-IO] [+IO] [-cC command] [arguments ... ] Options: -! Ignore errors: Continue execution even if a command terminates abnormally. (Implied by interactive.) -B Berkeley mode for better compatibility with the BSD4.3 C shell for commands typed, not just those read from a script starting with #!/bin/csh. -b No Berkeley compatibility mode at all, not even on scripts starting with #!/bin/csh. -c Execute the command following on the command line, then exit. (Implies not interactive.) -C Normally, this means immediately run the command on the command line, then continue with normal startup and processing of stdin. But for compatibility with cmd.exe, the -X option may be used to toggle this to have the same meaning as -c but with the initial greeting and copyright notice suppressed. -e Echo the raw input to stdout. -f Fast startup: Don't look for a startup.csh file. -F Faster startup: Don't look for a startup.csh file and don't hash the path directories. -H Heapstats. At some penalty in performance, this causes the shell to keep a count of the number and total size of all objects allocated or freed from the heap. Statistics can be displayed using the heapstat command. -i Interactive (even if stdin appears to be a file or a pipe): Prompt for input and show the result of history substitutions. -I Start with command-line editing in insert mode. +I Start every command in insert mode. -K Do a fast startup, skipping both the login.csh and startup.csh files, run the command on the command line, and exit. -L Login shell: Look for login.csh and logout.csh and do history save at exit if savehist == 1. Page 248 -l same as -L. -N No space after the last filename generated by filename completion. (It's convenient to set this with CSHOPTIONS.) -n No execution: Parse commands looking for syntax errors but don't execute them. -O Start with command-line editing in overstrike (default) mode. +O Start every command in overstrike mode. -s Read and execute a single line from stdin. (Implies not interactive.) -t Suppress callstack tracing. Error messages will not include a dump of the callstack but performance will be improved slightly. -u Reads from devices or pipes should be unbuffered. (Intended to all the shell to be used over a comm line.) -X Toggle between the normal meaning of -C and a cmd.exe-compatible interpretation. You can set this with the CSHOPTIONS environmental variable in combination with setting COMSPEC to point to the C shell to allow programs that use /C to pass commands to cmd.exe to be used with the C shell instead. -Z Very special purpose: Don't bump the maximum file handle count during shell initialization. Use this option under OS/2 as a workaround if you encounter an application that fails if it inherits a larger limit. This option only works from the Start Programs or Group menus, not the command line. Under NT, this option affects only the limit on the number of open file handles on a FAT filesystem; it has no effect on HPFS or NTFS files. -h Help. -- End of options. (If preferred, the slash, ``/,'' may be used in place of a minus to introduce options.) Page 249 Help Help for the Utilities binedit: Binary Edit Usage: binedit [-ih!-] [-r replace] search file1 [ file2 ... ] binedit is a very simple utility for scanning arbitrary files, looking for and optionally changing any references to the search argument to the replacement value. binedit is quite useful patching binary files, e.g., to replace all occurrences of C:\OS2 with C:\1.X. Occurrences will be reported as hex offsets from the start of the files you name. You can use these numbers to go examine the file with IBM/MS patch.exe if you like and make the change manually. You can also ask binedit to make the change, using the -r (replace) option. Nothing fancy. It just changes all occurrences to the string you specify and quits. Neither the search nor the replace string may contain null characters, but otherwise there are no restrictions. Options: -h Help. (This screen.) -i Ignore character case in the search argument. -r replace Replace any occurrences of the search string with this replacement value. -! Pad with nulls or truncate the replace string to be the same length as the search string. (Otherwise, it's an error if they're different lengths.) -- End of options. cat: Concatenate Files to Stdout Usage: cat [-h-] [ file1 file2 ... ] cat copies the files you specify, one immediately after another, onto stdout. No end-of-file or other delimiter characters are inserted between files. Page 250 Options: -h Help. -- End of options. cd: Change to a New Current Directory Usage: cd [-chr-] [+chr] [ directory ] cd works exactly like the one in cmd.exe by default: if you specify a directory, it tries to make that the current on appropriate disk but won't change your current disk. If you don't specify a directory, it reports the current setting. If the path you specify is just 3 or more dots, cd will interpret that specially. Just as ``..'' means go up one level, ``...'' means up 2 levels, ``....'' means up 3 levels, etc. Note that ``...'' is also a wildcard notation for zero or more directory levels, but only if it's preceded by ``\'', ``/'', ``~'' or ``:'' or followed by ``\'' or ``/'', so usually there's no conflict with this notation for going up multiple directories with cd. The exception is when you'd like to go up multiple directories on an explicitly specified drive; in that case, you'll have to quote the word to turn off the wildcarding. This version of cd also supports CDPATH. If you specify a path that isn't found, cd will look through the list of any directories you specify in the CDPATH environmental variable (or the equivalent cdpath shell variable) to see if the directory you want is in one of those directories. The syntax for CDPATH and cdpath is the same as for PATH or path except that the current directory need not be listed. (See also the dirs, pushd, popd and rotd commands.) Options: If you set the chgdisk variable equal to 1 (its default is 0), cd will automatically change current disks if the directory is on another drive. The +c and -c options allow you to manually control this drive switching: +c Automatically change the current disk. Page 251 Help -c Don't automatically change current disk. If you set the cdhome variable to 1 (its default is 0), cd will change to your home directory if you specify one instead of reporting your current position. You can manually control this with the +r and -r options: +r Report but don't change the current directory if no destination directory is specified. -r Change to the home directory in this situation. Page 252 -h Help. -- End of options. chcp: Report or Change the Code Page Usage: chcp [-h-] [ page ] Change to the specified OS/2 character set code page. If no page is specified, report the current active and prepared pages. (This command is not yet supported under NT.) Options: -h Help. -- End of options. chmod: Change Mode Bits on Files or Directories Usage: chmod [-+] [rRAHSh] pathname1 [ pathname2 ... ] Options: -r Recursively change contents of directories. +R Read-only mode is set. (The file is write- protected.) -R Read-only mode is turned off. +A Archive bit is set. -A Archive bit is turned off. +H Hidden mode is set. -H Hidden mode is turned off. +S Mark as a System file. -S Mark as a normal user file. -h Help. -- End of options. cls: Clear the Screen Usage: cls [-h-] Options: -h Help. -- End of options. Page 253 Help cp: Copy Files or Directories Usage: cp [-filmh-] source1 [ source2 ... ] destination cp can copy both files and directories. If the destination is an existing directory, the source object(s) will be copied into that directory. If more than one source object is specified, the destination must be a directory, but it need not already exist. If a destination file already exists, it will be overwritten; this is not considered an error and no diagnostic message is given. Options: -f Force read-only files to be overwritten. -i Interactive: ask before copying each object on the command line. -l Logging is on: display the name of each file or directory as it's copied. -m Merge sub-directories of same name in source and destination. -h Help. -- End of options. (Useful if filenames start with ``-''.) Page 254 cut: Cut out selected fields of each line of text, Usage: cut [-hsr-] [-c<list>] [-f<list>] [- d<delims>] [ file1 file2 ...] cut can be used to select certain columns or fields from each line of input. If the -c option is used, fields are defined as specific character positions. If the -f option is used, the fields can be of variable length, each field separated from the next by the delimiter character. If no files are specified, cut reads input data from stdin. A list of fields or character positions is specified as a comma-separated list of integers. The minus sign can be used to indicate a range. Here are some examples: 1,4,7; 1-3,8; -5,10 (short for 1-5,10); or 3- (short for third through last field.) Options: -h Help. (This screen.) -s Suppress lines with no delimiters in case of -f option. Otherwise, lines with no delimiters are passed through unchanged. -c<list> The list specifies character positions. -f<list> The list specifies field numbers. -d<delims> The specified characters are used as the field delimiters with the -f option. Any number of delimiters can be specified. The default is the tab character. -r Repeated delimiters are treated as if only a single delimiter had appeared. date: Print the Date and Time Usage: date [-nh-] date prints the day of the week, the date and time of day in 24-hour notation. This command is normally stored in the file dt.exe and invoked with an alias so it can be used from cmd.exe without colliding with the internal cmd.exe date function. Options: Page 255 Help -n Don't automatically append a Carriage Return/Line Feed sequence to the end of the output. -h Help. -- End of options. Page 256 des: DES Data Encryption Usage: des [-edbhnrz-] [-k key] [ file1 file2 ... ] des is a filter that encrypts or decrypts data read from the files you specify, one after another, to stdout with the Data Encryption Standard (DES). If no files are given, des reads from stdin. If there are multiple files, they're simply concatenated as they're read. Either -e (encrypt) or -d (decrypt) must be specified. If the key is not given on the command line with the -k option, des will prompt for it, suppressing echo. Distribution of this software is controlled by U.S. Federal Law under Title 22, Code of Federal Regulations, Subchapter M, Category XIII(b). It may not be exported outside the U.S. or Canada without an export license. Options: -e Encrypt. -d Decrypt. -b Electronic Code Book (ECB) mode is used. The default is to use DES Cipher Block Chaining (CBC) mode with an initial vector (IV) of all zeros. Under ECB mode, each block of 8 bytes is enciphered independently, depending only on the key. Under CBC mode, the enciphering of each block also depends on the data in the previous blocks. The default CBC mode is considered somewhat more secure. -k key Encryption key, typed as a simple ascii string. With an ascii key, DES ignores the low order bit of each key byte but the high order bit is set for odd parity, thus retaining the information contained in the low order bit. -x Hex key. The key string is a sequence of up to 16 hex characters, right padded with zeros. With a hex key, the low order bit of each byte is again ignored per the DES algorithm. This allows the use of any arbitrary 56-bit key, including bytes representing control characters that could not be typed. -h Help. (This screen.) Special Interchange Options: Page 257 Help Not all DES implementations are the same. There are a number of early implementations in circulation that either poorly or improperly implement DES. Cipher Block Chaining may not be supported, forcing the use of the -b option. You may also discover other flaws, necessitating that you experiment with some of these special options: -n Suppress parity calculation on an ascii key. Just use the low-order 7 bits of each character as-is. -r Convert all \r\n sequences to \n on input and all \n characters to \r\n sequences on output. (Some implementors have used the C library stdio read and write routines but have forgotten to use binary mode.) -z Do not mark the last block with a length; just fill it with binary zeros. If you encipher, then decipher a file this way, the result will be padded with zeros out to an 8-byte boundary. If you encounter problems exchanging encrypted data with another DES implementation, you should try all the various combinations of the -b, -n, -r and -z options. (We've seen one very poor implementation of DES that had all these flaws.) Notes: 1. If you lose the key to a file encrypted with DES, there is no known way to decrypt it. The data is lost. 2. When choosing keys, avoid anything obvious that someone else might easily guess. E.g., don't use just your name or your date of birth or a common word. Instead, choose a key with a seemingly random mix of alphanumeric and punctuation characters. 3. No encryption system should be considered perfectly secure. Although there are no known practical methods for attacking DES, such methods may exist. 4. Encryption can only protect data that's actually encrypted. If you have copies of the clear text on your disk, anyone with access to your machine may be able to read the data. Also, even when a file is deleted, the contents may remain on your Page 258 disk, accessible to anyone with knowledge of the file system. 5. If you would like to compress encrypted data, e.g., with utilities such as PKZip or ARC, compress first, then encrypt. The encryption process tends to destroy the redundancy in the data that compression programs depend on. Page 259 Help diff: Compare Files or Directories Usage: diff [-bBefhiqrvw!-] [-m minmatch] [- Dstring] oldpath newpath diff produces a list of differences between two files or directories. The working assumption is that newpath is a newer version of whatever's in oldpath. If they're files, diff assumes they contain ascii text but if it encounters a file containing lots of binary data, it switches to a binary comparison mode to avoid dumping gibberish to the screen. Comparing files, diff looks for minimal sections of change. Each difference is shown as an add, delete or change with the appropriate line numbers or line number ranges for each file. Following are texts of the differing section. Lines that have been deleted are flagged with '<'; lines that have been added are flagged with '>'. Alternately, diff can be used to produce merged listings with #ifdefs for the C compiler or highlighting for quick visual scanning. Comparing directories, the lists of files they contain all the way down through the tree are sorted, then compared. If the same filename exists in each directory tree, a quick binary comparison is normally made to give a quick yes- or-no are they different. If -r is specified, the diff text comparison is done recursively the whole way down the two trees. If one of the arguments to diff is a file and the other is a directory, diff will look for and compare against a file of the same name in the directory. Options: -b Blank spaces of any length compare equal. Ignore any leading or trailing white space on each line. -B Binary comparison even on text files. -Dstring Produce a merged #ifdef'ed listing, with the string being defined meaning use the older version. (Newer version is intentionally the default.) -e Turn off highlighting of empty lines. Byt default, if highlighting is used to show areeas of change, even empty lines will have Ansi sequences at the beginning and end so that if more is used to display the output Page 260 with the default color stretch mode on, empty lines will still be highlighted. -f Force diff-style comparison to continue even on files that appear to contain binary data. -i Ignore character case. -m minmatch Minimum match length to insist on before resynchronizing two files. (Default is 2 lines.) -q Quiet: supress warnings about files containing binary data. -r Recursively diff the contents of any subdirectories. -v Verbose listing of all the contents of any entire subdirectory added or deleted. -h Help. (This screen.) -w White space is ignored totally. -! Produce merged, highlighted version. Text that's unchanged is normal, deleted text is red, new text is green. -- End of options. Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black ADDITIONS Lines added Bright Green DELETIONS Lines deleted Bright Red Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits the color underneath it. ADDITIONS and DELETIONS inherit from COLORS. Page 261 Help dim: Discard any ansi escape sequences in the input stream Usage: dim [-h-] [ file1 file2 ... ] dim deletes any ansi escape sequences as it copies text from each of the files you specify onto stdout. If several files are given, they're concatenated one after another to the output. If no files are given, dim reads from stdin. Options: -h Help. (This screen.) -- End of options. dirs: List the Current Directory Stack Usage: dirs [-h-] Show the list of fully-qualified directory pathnames on the current directory stack, highlighting the current disk:directory pair. Hamilton C shell maintains a stack representing the current directory and any previous current directories has saved there. (See also the cd, pushd, popd and rotd commands.) Options: -h Help. -- End of options. Page 262 dskread: Read Raw Sectors from a Disk Usage: dskread [-bcdhHL-] [-n name] [-N sectors] [- s size] [-t tracks] [ disk: ] [ <sectorlist> ] dskread copies low-level raw sectors on the disk you specify to stdout. (This command is not yet shipping on NT.) In conjunction with dskwrite, dskread is most useful as a quick diskette duplication utility: you can read a whole diskette image into a file with dskread, then write it back out with dskwrite to a new diskette. But it's also useful for restoring a long stream of data dumped across a series of diskettes with dskwrite. The disk is given as a a single alphabetic drive letter plus a colon. If no disk is specified, the first logical drive is assumed (in most machines, this is the a: drive). Operation: dskread normally starts at cylinder 0, head 0, sector 0 and walks through the whole disk, reading all the sectors on a track under one head and then all tracks in a cylinder before repositioning the heads to the next cylinder. dskread always reads whole sectors except when reading from a file using the -d option. Options: -b Boot record. Skip sector 0 on the assumption it simply contains a standard boot record and parameter block corresponding to the particular media. -c Continuation. Assume the data has been split across several diskettes. After each disk has been read, prompt for the next one. If -d is specified also, the filename extension on each disk will be the disk number, i.e., 001, 002, 003, etc. -d Dummy filesystem. Assume the data is in a single file on the disk. If neither the -d nor the -b options is given, the disk will be read beginning with sector 0. -h Help. (This screen.) -n <name> The filename to look for if the -d (dummy file- system) option is used. Default is `bindata'. Page 263 Help -- End of options. Page 264 Formatting: Default is to let OS/2 or NT try to determine the formatting that was used. If the disk was written in unusual format or has non-standard data in sector 0, the following options can be override OS/2 or NT's attempt to guess the format: -H High density formatting. -L Low density formatting. -N <sectors> Sectors per track. -s <size> Sector size. Normally only 512 is supported but, depending on your hardware, you may also be able to create 128, 256 or 1024-byte sectors. -t <tracks> Number of tracks. Sector lists: Optionally, you can specify a list of sectors you want written. Sectors are given in (cylinder, head, sector) coordinates with parentheses around and commas or white space to separate the numeric values you write. Cylinders, heads and sectors are counted from zero and can be specified in decimal, hex or octal. A single sector specified alone means just that sector. Listing several separated by commas or spaces means each one individually. A pair of sectors joined by a hyphen means a range: all the consecutive sectors beginning with the first and running through to the second. Specifying a negative number as an ordinate means use the highest possible value for that disk. If any of the ordinates of a sector are omitted, they're assumed to be zero exept when it closes a range, in which case it means use the highest possible value. Examples: 1. To duplicate a whole diskette image, autoformatting the output media if it's not already formatted: Page 265 Help % dskread a: > dskimage.a % dskwrite -av a: < dskimage.a 2. To use a diskette as a serial archive media: The -d option allows you to request just enough dummy file system ``envelope'' around the otherwise arbitrary data you intend to write to ensure the disk can still be used with other OS/2 or NT utilities. Here's an example writing the result of a tar'ing (archiving) a whole directory to a series of diskettes, again autoformatting: % tar -asr mydir < nul | dskwrite -avcd -n mydir a: It's restored with % dskread -dc -n mydir a: | tar -xsr The diskettes used do not all have to be the same density; any mix of high and low is okay. But remember that if a disk isn't already formatted, there's no way for dskwrite to tell whether it should be high or low density; any disks it has to format will all be formatted the same way. If putting the greatest possible amount of data on a diskette is more important than compatibility with other OS/2 or NT utilities, you can also use the space normally devoted to the FAT file system and even the boot sector. Here is the same tar, written to a series of autoformatted high-density diskettes where every sector is used for data: % tar -asr mydir < nul | dskwrite -avcHx a: It's restored with % dskread -cH a: | tar -xsr Since no labeling of the data is written to the diskette, it's the user's responsibility to keep track of the order in which the disks were written and even what format was used. Page 266 dskwrite: Write Raw Sectors to a Disk Usage: dskwrite [-abcdfFhHLTvxz-] [-Z!] [-n name] [-N sectors] [-s size] [-t tracks] [-V volid] [ disk: ] [ <sectorlist> ] dskwrite copies stdin to the low-level raw sectors on the disk you specify. (This command is not yet shipping on NT.) In conjunction with dskread, dskwrite is most useful as a quick diskette duplication utility: you can read a whole diskette image into a file with dskread, then write it back out with dskwrite to a new diskette. But it's also useful for dumping a long stream of data across a series of diskettes, formatting and filling each as much as possible before requesting the next one. The disk is given as a a single alphabetic drive letter plus a colon. If no disk is specified, the first logical drive is assumed. (In most machines, this is the a: drive.) Operation: dskwrite normally starts at cylinder 0, head 0, sector 0 and walks through the whole disk, writing all the sectors on a track under one head and then all tracks in a cylinder before repositioning the heads to the next cylinder. You can also cause dskwrite to write to just specific sectors by giving it a sector list. dskwrite always writes whole sectors and, if requested, formats whole tracks. If the last sector is only partially-used, dskwrite fills it out with binary zeros. To avoid conflicts with other applications, dskwrite always locks a drive before actually writing to it. Basic Options: -a Autoformat. If the disk appears to be unformatted, automatically do a low-level format of the entire disk. -f Low-level format the entire disk as data is copied to it from stdin. -F Low-level format the entire disk and create an empty FAT filesystem. Do not read anything from stdin. -v Verify. Read back and verify each write. Page 267 Help -h Help. (This screen.) -- End of options. Page 268 Options for using the disk as a serial media: -b Boot record. Write a simple non-system disk boot record and parameter block corresponding to the particular media into sector 0. If writing the entire disk, continue with the next sector. -c Continuation. If there's more data on stdin after an entire disk has been written, prompt for a new disk to be inserted and continue. If -d is specified also, the filename extension on each disk will be the disk number, i.e., 001, 002, 003, etc. -d Dummy filesystem. Write a boot record and a FAT filesystem into the initial sectors allocating whatever is written to a single file. -n <name> The filename to be given to any data written onto the disk if the -d (dummy filesystem) option is used. Default is 'bindata'. Formatting: Default is to let OS/2 or NT try to determine how the media has been formatted and not to reformat the disk. If the disk isn't already formatted and the -a (autoformat) option is selected or if formatting is explicitly requested with the -f or -F options, dskwrite will do a low-level format of the media. dskwrite takes its specification of the format (e.g., low- or high-density) from the following sources, in decreasing priority: 1. Explicit specifications on the command line. 2. The OS/2 or NT kernel's guess at the media format, assuming the disk is already formatted and not being re-formatted. 3. The format parameters in the boot sector copied from stdin, assuming neither the -b nor the -d options is given. 4. The previous format of the media, assuming it's already formatted in a standard configuration but being reformatted. 5. The highest-density format supported by the drive. Unless you specify -b or -d, dskwrite will expect to copy a compatible disk image from stdin including a suitable boot sector, etc. That Page 269 Help happens automatically when dskread'ing a whole disk is paired with dskwrite'ing a whole disk but not otherwise. Page 270 Explicit Format Specification Options: -H High density format. -L Low density format. -N <sectors> Sectors per track. -s <size> Sector size. Normally only 512 is supported but, depending on your hardware, you may also be able to create 128, 256 or 1024-byte sectors. -t <tracks> Number of tracks. Other Advanced Options: -T Low-level format the media track-at-a-time as the disk is written. Only as much of the disk as is being written to will be formatted. -V <volid> The volume identifier to be written into the dummy filesystem header if -F or -d is used. (Ignored otherwise.) -x Force use of a non-standard format or writing of non-standard format parameters to the boot sector. -z Zero-length files written with -d option should still be added to the directory. (Otherwise, they're ignored.) -Z! Force write to a hard disk. Warning! Very risky unless you know exactly what you're doing. Sector lists: Optionally, you can specify a list of sectors you want written. Sectors are given in (cylinder, head, sector) coordinates with parentheses around and commas or white space to separate the numeric values you write. Cylinders, heads and sectors are counted from zero and can be specified in decimal, hex or octal. A single sector specified alone means just that sector. Listing several separated by commas or spaces means each one individually. A pair of sectors joined by a hyphen means a range: all the consecutive sectors beginning with the first and running through to the second. Specifying a negative number as an ordinate means use the highest possible value for that disk. Page 271 Help If any of the ordinates of a sector are omitted, they're assumed to be zero exept when it closes a range, in which case it means use the highest possible value. Examples: 1. To duplicate a whole diskette image, autoformatting the output media if it's not already formatted: % dskread a: > dskimage.a % dskwrite -av a: < dskimage.a 2. To use dskwrite to format a disk with an empty FAT file system, use either: % dskwrite -F a: or: % dskwrite -df a: <nul 3. To rewrite just the boot sector to make it a non-system disk: % dskwrite -b a: <nul 4. To use a diskette as a serial archive media: The -d option allows you to request just enough dummy file system ``envelope'' around the otherwise arbitrary data you intend to write to ensure the disk can still be used with other OS/2 or NT utilities. Here's an example writing the result of a tar'ing (archiving) a whole directory to a series of diskettes, again autoformatting: % tar -asr mydir < nul | dskwrite -avcd -n mydir a: It's restored with % dskread -dc -n mydir a: | tar -xsr The diskettes used do not all have to be the same density; any mix of high and low is okay. But remember that if a disk isn't already formatted, there's no way for dskwrite to tell whether it should be high or low density; any disks it has to format will all be formatted the same way. Page 272 If putting the greatest possible amount of data on a diskette is more important than compatibility with other OS/2 or NT utilities, you can also use the space normally devoted to the FAT file system and even the boot sector. Here is the same tar, written to a series of autoformatted high- density diskettes where every sector is used for data: % tar -asr mydir < nul | dskwrite -avcHx a: It's restored with % dskread -cH a: | tar -xsr Since no labeling of the data is written to the diskette, it's the user's responsibility to keep track of the order in which the disks were written and even what format was used. Non-standard Diskette Formats: If you write anything but a standard boot record into the boot sector, you will not be able to read it with anything but dskread and even then only if you tell it explicitly what what format was used. Without a standard parameter block in the boot sector, the the OS/2 and NT diskette device drivers just can't tell on its own how the diskette was written. Similarly, it's possible you may be able to write a non-standard format (e.g., a sector size other than 512 bytes, etc.) depending on your hardware. But doing that may make the diskette impossible to read on other machines. For that reason, dskwrite normally won't let you write a boot record that doesn't match the actual format of the diskette nor will it let you write anything other than one of the standard format. To override these checks, you must use the -x option. Writing to a Hard Disk: Deliberately, dskwrite normally only lets you write to diskettes. Writing to a hard disk is very risky since the chance of catastrophic loss of information is so Page 273 Help high. Also, only ESDI and SCSI disk controllers routinely map out bad blocks, so reading the disk image from one drive and writing it to another is unlikely to work if there are bad blocks on either one. To force dskwrite to write to a hard disk, you must specify the -Z! option, meant to be hard to accidentally type. In effect, the -Z! option means you understand the risk you're taking. Page 274 du: List Disk Usage Statistics Usage: du [-acdxvh] [ disk1 disk2 ... ] du prints statistics showing the total, used and free space on each disk partition. If no disks are specified, du looks for a DRIVEMASK environmental variable that can be used to mask off just the drive you want reported. The DRIVEMASK is specified as a list of drive letters; ranges are allowed. Otherwise, all the fixed disk partitions beginning with c: are reported. The current disk's statistics are highlighted. Sizes are normally reported in binary (1000*1024) megabytes. Option: -a If no disks are specified, report on all disks. -c If no disks are specified, report on just the current disk. -d Report in decimal (1,000,000) megabytes. -x Report in hex (1024*1024) megabytes. -v Give detailed cluster information. -h Help. -- End of options. Name Use Default COLORS Normal screen colors White on Black HIGHLIGHT Current disk or directory. Bright Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits the color underneath it. HIGHLIGHT inherits from COLORS. Page 275 Help echo: Echo the Arguments to Standard Output Usage: echo [-n2h-] [ text ] Echo the text to standard output (or stderr), substituting for certain character sequences preceded by the escapesym character. (The escapesym character is normally `^' but can be changed with the set command.) ^a Audible Alert (Bell) ^r Carriage Return ^b BackSpace ^t Tab ^f Form Feed ^v Vertical Tab ^n NewLine ^^ Single escapesym The escapesym character may also be followed with the numeric value of the intended substitution character where the value is specified in hex (as an 'x' followed by hex digits) or in octal. Options: -n Don't automatically append a Carriage Return/Line Feed sequence to the end of the output. -2 Write to stderr instead of stdout. -h Help. -- End of options. Page 276 eval: Parse & Evaluate at Run-Time Usage: eval [delta] [-irfth-] [ argument words ] Evaluate the words following on the command line as text to be parsed and evaluated as statements only after all the substitutions and wildcarding have been done. Optionally, under OS/2, eval lets you run the command at a higher or lower scheduling priority. Command or variable substitutions aren't normally done until after statements have already been parsed and compiled into an internal form and, if it's a background statement, passed off to a background child thread. The eval command is useful if either: - You want command or variable substitutions to be recognized as any of the reserved words of the language or as an alias, or - You want the substitutions done before a background thread is started, or - You want to run the command at a different priority. Options: -i Idle time priority. (In Unix terms, this is the ``nice'' option: if you're nice, you run at idle priority and let everything else run ahead of you.) -r Regular priority. (The usual initial value.) -f Foreground priority. -t Time critical priority. delta A signed integer amount by which the scheduling priority for this command is to be adjusted up or down. The `+' or `-' sign is required to distinguish this as an option. Priority ranges from 0 to 31 and is normally 0 when the C shell starts up or if a new priority class is chosen. Attempting to set priority below 0 or above the maximum results in priority 0 or 31 respectively. -h Help. -- End of options. Page 277 Help fgrep: Fast string search (fast grep) of text files Usage: fgrep [-hbcilnqsvwx-] [-f ptrnfile] [ pattern ] [ file1 file2 ...] fgrep does a quick, deliberately simple string search. It does not use regular expressions, but does have some diff-style options for ignoring upper-/lower-case differences or treating white spaces of any length as equal, etc. You can also give it a list of strings you want searched for, one per line in a pattern file or via stdin. Each matching line is copied to stdout. If more than one file is being searched, each line is preceded by the name of file where the match occurred plus a `:' character. Options: -h Help. (This screen.) -b Blank spaces of any length compare equal. Ignore any leading or trailing white space on each line. -c Just print a count of the number of lines which match. -f ptrnfile Read the patterns from a file. -i Ignore character case. -l Show just the names of any files containing at least one match. Show each name only once, each on a separate line. -n Show the line numbers of any matches. -q Quiet: don't show filenames where the matches occur. -s Read the patterns from stdin. -v Invert the pattern: show all lines except those that match. -w White space is ignored totally. -x Exact match: the whole line must match the pattern. -- End of options. Page 278 grep: Regular expression pattern search of text files Usage: grep [-hcilnqsv-] [-f ptrnfile] [ pattern ] [ file1 file2 ...] grep uses special patterns called regular expressions to filter what it reads from stdin or from any files you specify. Regular expressions are written in this notation, in decreasing precedence: c Any ordinary character matches itself. \c Match the literal character c. ^ Beginning of line. $ End of line. . Match any single character. [...] Match any single character in the list. [^...] Match any single character not in the list. \n Match whatever literal text the n'th tagged $...$ expression matched. r* Match zero or more occurrences of r. r1r2 Match expression r1 followed by r2. $r$ Tagged regular expression. Match the pattern inside the $...$, and remember the literal text that matched. A regular expression pattern cannot contain Null, NewLine or CarriageReturn characters. When typing a regular expression on the command line, remember that $, [, ], ^, ( and ) have special meaning to Hamilton C shell. Put single quotes around the string to turn off that special meaning. Also, even inside quotes, type ^^ to mean ^ except when it immediately follows [. Each matching line is copied to stdout. If more than one file is being searched, each line is preceded by the name of file where the matched occurred plus a `:' character. Options: -h Help. (This screen.) -c Just print a count of the number of lines which match. -f ptrnfile Read the patterns from a file. -i Ignore character case. Page 279 Help -l Show just the names of any files containing at least one match. Show each name only once, each on a separate line. -n Show the line numbers of any matches. -q Quiet: don't show filenames where the matches occur. -s Read the patterns from stdin. -v Invert the pattern: show all lines except those that match. -- End of options. hashstat: Print Path Hashing Performance Statistics Usage: hashstat [-h-] Summarize the recent effectiveness of the path hashing mechanism. Hamilton C shell uses a hashing mechanism to help it decide which path directories and filetype extensions should tried first when looking for an executable file. This way, it avoids wasting time with requests to the OS/2 or NT kernels to look for files that are known to be non-existent. Sometimes, the first guess made this way is wrong (the hash says a file might exist, but it doesn't) and the shell has to try again with a different directory or extension. hashstat shows you the hit rate, which is the number of hits divided by the number of tries (hits plus misses.) Blindspots are files that aren't found using the hash but are found on a second pass, using an exhaustive search. Blindspots happen when you add new files to a path directory; when detected, they cause the directory to be rehashed. (See also the rehash and unhash commands.) Options: -h Help. -- End of options. Page 280 head: Copy the first few lines or bytes of a file to Stdout Usage: head [-hbnq<size>-] [-t<tabs>][ file1 file2 ... ] head copies the first part of each of the files you specify onto stdout. If several files are given, each is announced unless you specify quiet mode. You may specify how much to read from each file in either lines or bytes. If no files are given, head reads from stdin. Options: -h Help. (This screen.) -c Count characters. (Default is lines.) -q Quiet mode. Don't announce the name of each file as it's read. -<size> Amount to be read from each file. (Default is 10 lines or 512 bytes.) -t<tabs> Tab settings to use for viewing text. (Default is to use value given by the TABS environment variable or, if that's undefined, to do no tab expansion.) -n No tab expansion. -- End of options. heapstat: Print Heap Usage Statistics Usage: heapstat [-h-] Summarize the current heap usage, i.e., the number of objects allocated on the heap and the total storage used. Heapstats are only available if they were enabled with the -H option when the shell was started. Because of the significant performance penalty associated with tracking heap usage, heapstats are not normally enabled. Options: -h Help. -- End of options. Page 281 Help history: Display the History List Usage: history [-srh-] [ n [m] ] Display commands from the history list. If no operands are given, show the entire list. If a single integer `n' is specified, display the last n commands. If both integers `n' and `m' are given, then: if m >= n: Display commands numbered n through m. if m < n: Display m commands, beginning at command n. (The size of the list is controlled by the history variable, changed using the set command.) Options: -s Short form: Leave off the command numbers. -r Reverse order: Show the oldest first. -h Help. -- End of options. kill: Kill Specified Process or Thread Activity Usage: kill [-xh-] scheduling_id [ scheduling_id ... ] Terminate specific activities. Normally, only direct child screen groups and processes can be killed. Only certain threads will respond to a kill; you cannot inadvertently kill normal internal housekeeping. Scheduling_ids are the thread, process or screen group identifiers as reported by the ps command. An id beginning with `t' indicates a thread; `p' indicates a process; `s' indicates a screen group. (Screen groups are only on OS/2.) Options: -x Kill even processes that are not direct children. (Has no effect on OS/2 screen groups that are not direct children; this is an OS/2 kernel restriction.) -h Help. -- End of options. Page 282 label: Read/Write the Volume Label Usage: label [-h-] [ disk: ] [ label ] label reads or writes the label on the specified disk, given as a single alphabetic drive letter plus a colon. If no disk is specified, the current disk is assumed. If no label is specified, the current label name is printed. Otherwise label tries to set the label to specified name. Spacing between the disk: and the label operands is optional. The principal differences between this and the standard OS/2 or NT label command are that (1) it can be invoked directly from the C shell (the standard OS/2 label had a bug in its command line processing that meant it had to be invoked only via cmd.exe), and (2) it never prompts, making it more suitable in scripts. Options: -h Help. (This screen.) -- End of options. Page 283 Help ls: List Files or Directories Usage: ls [-+][lL!rqhx- ndtsez mU DHSARa 0-9 wME] path1 [ path2 ... ] ls lists the specified files or directories. Directory names are highlighted; names of files or directories with the system bit set are shown in green. File and directory names are normally converted to lower case for better readability. But ls will look for an environmental variable, MIXEDCASEDRIVES, giving a list of drives, e.g., f-hq, meaning drives F: through H: and drive Q:, which should be displayed in mixed case. To customize ls with a default behavior of your own choosing, use the LSOPTIONS environmental variable. ls will first process any options specified in LSOPTIONS before any specified on the command line. General Options: -l Long format listings of the files or directories. -L Very Long format listings. (Under OS/2 1.1, used and allocated media space is always reported. Under 1.2, the size of any extended attributes is shown instead of media space if -E is specified. Also, under 1.2, root directories do not have a timestamp and are reported as midnight, Jan 1, 1980) -! List just the names specified, not the contents of any directories. (Remember to type this option at the end of the list so the space afterward will prevent it being confused as a history reference.) -r Recursively list contents of any subdirectories. -q Quiet. Don't generate an error message for non-existent files. -h Help (short list.) -hx Extended help (this description.) -- End of options. (Useful if filenames start with ``-''.) Page 284 Sorting Options: Sorts may be done in any order; default is -nds. (The filename is the most important sort criteria and ties are broken by date or size.) -n Name (lowest alphabetic first.) -d Date (oldest first.) -t Time (newest first; same as -dz) -s Size (largest first.) -e Extension (lowest alphabetic first.) -z Reverse the major or last specified sort. -m Merge the listings of directories and files. -U Unordered (in order of appearance in the directory.) Selection Criteria: +<type> Include files/directories fitting this pattern. -<type> Leave out anything fitting this pattern. where <type> is combination of following characters: D Directories. H Hidden files or directories. S System files or directories. A Archive bit set. R Read-only files or directories. . ``.'' and ``..'' files. a All files or directories regardless of attributes. The default is ``+a -. -H'', meaning list anything other than ``.'' and ``..'' not marked Hidden. Anything specified is added to/subtracted from this set. Ordering of additions or subtractions does make a difference. If the slash, ``/'', is used to introduce options, it is treated as a plus when used with selection criteria. Selection criteria normally applies only to directories and files found by listing a directory. All names given on the command line will be listed if they exist regardless of whether they match the selection criteria unless the -c option is specified. -c Command line names must match criteria also, unless only one name is given. Page 285 Help Listing Options: -<integer> Specified number of columns. -0 Standard multi-columns on an 80-column screen. -C Capitalization. Display filenames in the upper- or lower-case characters actually stored in the file system. -w Walk subdirectories to show true sizes in long format listings. -M Media allocation is shown instead of amount used with -l. -E Extended attribute size is shown instead of media allocation with -L. (-E is ignored under OS/2 1.1.) Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black DIRECTORIES Directories Bright SYSTEMFILES Files with system bit set Green SYSTEMDIRS Directories with system (see below) bit set Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits the color underneath it. SYSTEMDIRS normally inherits a merging of the DIRECTORIES and SYSTEMFILES colors. DIRECTORIES and SYSTEMFILES inherit from COLORS. Page 286 markexe: Mark the application type bits in an .exe file Usage: markexe [-ftpzslh-] file1 [ file2 ... ] markexe reports or sets the application type bits on OS/2 .exe files to indicate how the application should be started, i.e., whether they must run full-screen, can run in a text window or must be started as full PM graphics applications. If the .exe is a 16-bit application, markexe can also be used to indicate whether it supports long filenames. (All 32-bit applications must, by definition, support long filenames.) If no flags are specified, the types are reported but not altered. Application Types: -f Full-screen. -t Text windowable. -p PM graphics. -z Zero the type bits. (Undefined type.) Long Filename Support (ignored for 32-bit .exe files): -s Short filenames only. -l Long (HPFS-style) filenames supported. Other Options: -h Help. (This screen.) -- End of options. mkdir: Make Directories Usage: mkdir [-h-] directory1 [ directory2 ... ] Options: -h Help. -- End of options. Page 287 Help more: A Better More Filter Usage: more [-#IinNcvbodxCh-][-rradix][-ttabs][-sscroll] [file1 file2 ... ] This more provides a number of advantages over the standard more.com filter. It's faster, goes backwards and forwards through a file, can search for character strings and display binary data embedded in the text. As it reads a file, it builds an ISAM structure on-the-fly that lets it jump to a specific line number almost instantaneously. It's designed for very fast browsing. On-line help is available to the key bindings by pressing ``h'' when you see the Press H for Help prompt at the bottom of a screenful of data. For OS/2, there are two versions of more: more.exe is built in small model and can cache about 11K characters; a ``huge'' version, moreh.exe, is built in large model and while slightly slower, can cache about 4M characters. Where speed is less important than being able to scroll all the way back through a large amount of text coming through a pipe, use moreh.exe, which was compiled in large model. Options: -# Show line numbers. -I Start up in case-independent search mode. -i Go into Interactive mode immediately, which means clear the screen first for faster painting and put up the Press H for Help prompt rather than just exiting if there's less than a screenful of input. -n Next file option. Pressing space bar when the end-of-file message is displayed causes more to continue with the next file or to exit if there are no more files. -N No stretch. Don't stretch color changes out to the right edge of the screen. -c Show non-printables in C language style. -v Make non-printables Visible as control characters. -b Show Binary values of non-printable characters. -o Use Octal for binary data. -d Use Decimal for binary data. -x Use Hexadecimal for binary data. Page 288 -C Don't clear the screen before each new screenful. -rradix Use user-specified radix for binary data. -ttabs Set tabs every integer number of spaces. -sscroll Set the integer default scroll amount. -- End of options. (Useful if a filename begins with ``-''.) Initial tab settings and radix values are taken from the environmental TABS and RADIX variables if they're defined. Otherwise, TABS = 8 and RADIX = 16 is assumed. Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black MOREEOF End or Top of File messages Green MORETOPMEM Top of Memory message Bright Yellow MOREPROMPT Prompt line at the bottom Green MOREFILLIN Characters typed at the White prompt MOREERROR Unrecognizable command Bright Yellow errors Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits the color underneath it. MOREERROR and MOREFILLIN inherit from MOREPROMPT. MOREPROMPT, MORETOPMEM and MOREEOF inherit from COLORS. Page 289 Help mv: Move Files or Directories Usage: mv [-filmh-] source1 [ source2 ... ] destination mv is an intelligent file or directory mover. It's able to move either files or directories as objects regardless of whether the source and destination are in the same directory or even the same drive. Files being moved anywhere on the same partition are simply renamed; the data stays where it is. Moving a file to a different partition is done by copying the file and then deleting the original. If you move a directory but it keeps the same parent, that also is a simple rename. Moving a directory to a new parent is done by a mkdir in the new parent and moving all the directory contents using the same ``rename where possible'' strategy recursively. Options: -f Force read-only files to be overwritten. -i Interactive: ask before moving each object on the command line. -l Logging is on: display the name of each file or directory -m Merge sub-directories of same name in source and destination. -h Help. -- End of options. (Useful if filenames start with ``-''.) newer: Test whether file1 is newer than all the others Usage: newer [-h-] [ file1 file2 ... ] Prints ``1'' if file1 is newer, otherwise prints ``0''. Options: -h Help. -- End of options. Page 290 older: Test whether file1 is older than all the others Usage: older [-h-] [ file1 file2 ... ] Prints ``1'' if file1 is older, otherwise prints ``0''. Options: -h Help. -- End of options. patchlnk: Patch ``The linker bug'' Usage: patchlnk [-hcw-] filename patchlnk can be used to patch a specific bug in your linker if you're having problems linking under the Hamilton C shell on OS/2. (See also the discussion under ``Known Bugs'' in the readme.too file sent with Hamilton C shell.) If you're having problems linking long lists of .obj files, you should save a copy of your link.exe the way it is, then patch your linker with this program and see if the problem goes away. Microsoft has discovered they had a bug in the version of the C library used to build their link.exe releases (roughly) 5.01.21 through (and possibly past) 5.03. In the file open routine, they had an ``off by one error'' that caused problems if the DosSetMaxFH (maximum file handles) parameter for the process allowed more than 20 file handles to be open. There's a JLE (0x7e) that should have been a JB (0x72). It occurs in the following byte string (in hex): 3b 06 ?? ?? 7e 0d 9a where the ?'s mark bytes that can change because they refer to data locations that move from one build of link.exe to the next. (Since the problem is in the MS C library, the bug could affect any C program that tries to simultaneously open 20 or more handles with stdio. So far, MS link.exe is only application known to do this but there could be others. patchlnk should work on them also and probably even on your MS C library .lib files.) Page 291 Help patchlnk will scan through the file, looking for occurrences, which it will report as hex offsets from the start of the file you name. You can use these numbers to go examine the file with IBM/MS patch.exe if you like and make the change manually. You can also ask patchlnk to make the change, using the -w (write) option. Nothing fancy. It just changes the first occurrence and quits. (If you really think you want any other occurrences patched, just keep rerunning this.) If want to look for changes already made, use -c. Options: -h Help. (This screen.) -c Look for changes already made. -w Write the first change. -- End of options. popd: Pop a new Current Directory and Disk off the Stack Usage: popd [-dsh-] [ n ] Pop an integer n directory paths from the top of the stack, making the top one remaining the new current directory and disk. The default for n is 1. (See also the cd, dirs, pushd and rotd commands.) Options: -d Discard just stack entry n, counting from 0 at the top, popping everything below it up one level -s Silent. Don't print the resulting directory stack. -h Help. -- End of options. Page 292 ps: Print Process & Thread Status Usage: ps [-h-] Show the status of all the screen groups (OS/2 only), processes and threads related to this invocation of Hamilton C shell, highlighting the current thread. Screen groups are created when a command you type requires a different style of window than is currently running. Screen ids begin with `s'. Processes are created when commands are typed that require other executable programs to run. Process ids begin with `p'. OS/2 and NT will only provide information on direct child processes. Threads are concurrent activities going on inside Hamilton C shell. Some, such as the cleanup activities that watch for other threads or processes to end always run in the background. Others are created when a command requires that an internal function be run in the background. Thread ids begin with `t'. Options: -h Help. -- End of options. pushd: Push a new Current Directory and Disk onto the Stack Usage: pushd [-hs-] [ -c [n] ] [ directory ] Go to a new current directory and disk, saving the old values on the directory stack. If no operands are given, swap the top two elements of the stack. If the path you specify is just 3 or more dots, pushd will interpret that specially. Just as ``..'' means go up one level, ``...'' means up 2 levels, ``....'' means up 3 levels, etc. If the directory isn't found, the CDPATH is searched. (See also the cd, dirs, popd and rotd commands.) Options: -c Copy an item already on the stack onto the top. This form takes an optional parameter n which specifies the integer item number Page 293 Help counting from 0 at the top. Default is n == 0. -s Silent. Don't print the resulting directory stack. -h Help. -- End of options. Page 294 pwd: Print the Current Working Directories Usage: pwd [-ch-] [ disk1 disk2 ... ] pwd prints a list of the current directories. If no disks are specified, pwd looks for a DRIVEMASK environmental variable that can be used to mask off just the drive you want reported. The DRIVEMASK is specified as a list of drive letters; ranges are allowed. Otherwise, all the fixed disk partitions beginning with c: are reported. The current directory on the current drive is highlighted. pwd routinely reports everything in lower case for better readability. But pwd will look for an environmental variable, MIXEDCASEDRIVES, giving a list of drives, e.g., f-hq, meaning drives F: through H: and drive Q:, which should be displayed in mixed case. Options: -a If no disks are specified, report on all disks. -c If no disks are specified, report on just the current disk. -h Help. -- End of options. Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black HIGHLIGHT Current disk Bright Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits Page 295 Help the color underneath it. HIGHLIGHT inherits from COLORS. Page 296 rehash: Reinitialize Path Hashing Usage: rehash [-h-] Hamilton C shell uses a hashing mechanism to speed up searches of the path directories. If you're performing system administration work, moving files in the path directories, the hash mechanism may not always reflect the latest changes you've made. The rehash command allows you to turn re-initialize the hash by re-reading all the path directories and setting nohashing = 0. (The unhash command can be used to turn hashing off.) Options: -h Help. -- End of options. Page 297 Help rm: Remove Files or Directories Usage: rm [-rfHSxilh-] pathname1 [ pathname2 ... ] rm can delete both files and directories. If you try to remove a file with one of the special mode bits set (see chmod) or a directory that's not empty, it'll refuse unless you use one of the options to let it know that's really what you mean. Options: -r Recursively remove non-empty directories. -f Force read-only files or directories to be removed. -H Hidden files or directories can be removed. -S System files or directories can be removed. -x All of the above. -i Interactive: ask before removing each object on the command line. -l Logging is on: display the name of each file or directory as it's removed. -h Help. -- End of options. (Useful if filenames start with ``-''.) rmdir: Remove Directories Usage: rmdir [-h-] directory1 [ directory2 ... ] rmdir will only remove empty directories. Mode bits (system, hidden or read-only) are ignored. Options: -h Help. -- End of options. Page 298 rotd: Rotate the Directory Stack Usage: rotd [-hs-] [ n ] Rotate the directory stack an integer n positions. Positive values cause upward rotation; negative values cause downward rotation. The default is upward rotation by one position.) (See also the cd, dirs, pushd and popd commands.) Options: -s Silent. Don't print the resulting directory stack. -h Help. -- End of options. sed: Stream Editor Usage: sed [-hins-] [-f scriptfile ] [-e script] [ script ] [ file1 file2 ...] sed is a special text editor for use on streams of data where it cycles, reading a line from input, applying the editing operations you've specified, and writing the result to stdout. The input is read in a single pass and each line is acted on only once. The editing script can be specified on the command line or, if it's long and complex, in a file. If you want to combine a script on the command line with any other script, you must use the -e option. The editing operations available are the usual search/replace, insert/delete, etc. With each operation, you generally can specify the lines in the file it should affect either by line number or matching a pattern or a range of lines. Options: -h Help. (This screen.) -f scriptfile Read the script from a file. Multiple -f options are allowed and the scripts are concatenated. -e script Take the following argument word as a script. Multiple -e options are allowed. -i Ignore character case. Page 299 Help -n Don't automatically write the contents of the edit buffer to stdout at the end of each cycle. -s Read the script from stdin. (The input stream to be edited must be in a file.) -- End of options. Page 300 Scripts: The script is written as a series of commands, each separated from the next by a line end or a semicolon. The format of a command is: [ address1 [ , address2 ] ] operation Spacing between fields is arbitrary: you can use spaces or tabs between fields or have none at all as you prefer. Here are the fields: address is a line number or regular expression to be matched. When a regular expression is used as an address, it's normally written as /regexp/ but it's also possible to use the syntax \?regexp? where ? is any character. Zero- or One-Address Operations: If you don't give an address, the operation is applied to all lines. If you give a single address, the operation is done on each line that matches. Ranges: When you give two addresses, you define a range. A range can be a single line, e.g., ``3,3'', or a whole group of lines. If the addresses involve pattern matching, e.g., ``/^#ifdef/,/^#endif/'', the range might occur over and over in the input and will be acted on each time. Most operations, e.g., search/replace, are done against all lines in the range. The exceptions are i\ (insert), which is acted on at entry to the range; a\ (append), and q (quit), which are acted on at the end; and c\ (change), which deletes all the lines in the range but doesn't write any output until the end of the range. Page 301 Help operation is one of the 28 basic operations provided, together with any arguments it takes. Page 302 Operations: There are two buffers in sed: the edit buffer and the hold buffer. Most of the editing operations work on the edit buffer, doing search/replace operations, translating characters, and saving or retrieving text in the hold buffer. sed automatically puts each new line into the edit buffer (along with its trailing line end) at the start of each cycle unless there was something left over after a D (delete head) command. A second group of operations provide ways of inserting blocks of static text. The next group of operations provide rudimentary ways of condition-testing and branching and of nesting a series of operations together. Finally there operations for printing and doing other i/o and for other miscellaneous things. Basic Editing: d Delete this section. Start the next cycle. D Delete from the beginning of edit buffer through and including the first line ending. If there's text remaining, immediately start over at the top of the script without reading a new line. s/.../.../[ngpw] Search/replace using regular expressions. In the replace string, ``&'' means whatever the search string matched. ``\n'', where n is a number, means whatever matched that tagged expression in the search string. The search and replace strings are shown here delimited with /, but you may choose any character you like that doesn't occur in either string. The following modifiers are accepted: n A decimal number from 1 to 65,535. Substitute for just the n'th occurrence of the search pattern. g Global. Substitute all occurrences. p Print the edit buffer if a change was made. Page 303 Help w file Write the edit buffer onto the end of the file if a change was made. y/.../.../[c] Translate all occurrences of characters in the first string to the corresponding characters in the second string. As in the tr utility, ranges are allowed, as in ``y/a-z/A-Z/''. The optional ``c'' flag can be used to complement the input range. Either string can contain \r and \n characters. If the first string is longer than the second, all the extra characters are mapped to the last character in the replacement string or to a null if there was none. If the second string is longer, the extras are ignored. Using the Hold Buffer: g Get from the hold buffer. Replace the current contents of the edit buffer. G Get from the hold buffer and paste onto the end of the edit buffer. h Hold. Replace the contents of the hold buffer with a copy of the edit buffer. H Append to hold. Copy the edit buffer contents onto the end of the hold buffer. x Exchange the edit and hold buffers. Inserting blocks of Static Text: a\ \r\n text Append the text to the output at the end of the cycle if this is the last line in the range. All but the last line of text should have a ``\'' just before the \r\n sequence at the end of each line. c\ \r\n text Change this section to read as shown in the following text. Start the next cycle. i\ \r\n text Insert. Immediately copy the following text to stdout if this is the start of the range. Condition-Testing, Branching and Grouping operations: Page 304 b label Branch to the label elsewhere in the script. (If no label is given, it's to the end of the script.) q If this is the end of the range, quit. t label Branch to the label if search/replace changes have been made since the most recent input line was read or a t operation was run. : label Label. (No address prefix is allowed.) { } Group a series of operations together. Page 305 Help Printing: = Write the line number to stdout. l List the contents of the edit buffer in C language style with escape sequences for binary characters. p Print. Write the contents of the edit buffer to stdout. P Print from the beginning of the edit buffer through and including the first line ending. #n Suppress any automatic output at the end of each cycle. Other I/O operations: n Next line. Write the contents of the edit buffer to stdout, dump any appended text and read a new line from stdin to the edit buffer. N Read the next line onto the end of the edit buffer with a \r\n sequence in between. r file Copy the contents of this file to stdout at the end of the cycle. w file Write the edit butter onto the end of the file, creating it if it doesn't exist. Miscellaneous: ! operation Don't apply this function unless the addressing doesn't match. Invert the line selections. ; Null statement. # comment Comments and blank lines are ignored. If multiple a\ (append) or r (read file) instructions are executed (or the same one is iterated in a loop), a new entry is made on the end of a list of all the appended text blocks to be copied to stdout at the end of the cycle. When the end of the cycle is finally reached, the whole list is dumped, in order from the top. Page 306 Regular Expressions: Search patterns are specified as regular expressions like those used by grep. Regular expressions are written in this notation, in decreasing precedence: c Any ordinary character matches itself. \c Match the literal character c. ^ Beginning of line. $ End of line. . Match any single character. [...] Match any single character in the list. [^...] Match any single character not in the list. \n Match whatever literal text the n'th tagged $...$ expression matched. r* Match zero or more occurrences of r. r1r2 Match expression r1 followed by r2. $r$ Tagged regular expression. Match the pattern inside the $...$, and remember the literal text that matched. A regular expression pattern cannot contain Nulls but it can contain NewLine or CarriageReturn characters (which may be useful with the N or G commands.) When typing a regular expression on the command line, remember that $, [, ], ^, ( and ) have special meaning to Hamilton C shell. Put single quotes around the string to turn off that special meaning. Also, even inside quotes, type ^^ to mean ^ except when it immediately follows [. Also, / at the beginning of a word on the command line is taken as introducing an option. If you mean it to be the start of a script, use the ``--'' option ahead of it. Page 307 Help setrows: Set/Report the number of rows in the display window Usage: setrows [-h-] [ rows ] setrows will try to set the vertical height of the current window to the specified number of rows. In a PM text window, almost any reasonable number of rows can be chosen, but full-screen, you can choose only from this set: 12, 14, 21, 23, 24, 25, 27 to 30, 33, 34, 39 to 43, 45 to 50 and 54 to 60. (Your hardware may not support all these possibilities.) If the number of rows is not specified, setrows just reports the current value. (setrows is supported only on OS/2.) Options: -h Help. (This screen.) -- End of options. sleep: Sleep for a Specified Period Usage: sleep [-hm-] [ seconds ] Sleep the specified integer number of seconds (rounded to the next clock tick.) Default is 1 second or until an interrupt occurs. Options: -m Sleep interval is in milliseconds rather than seconds. -h Help. -- End of options. Page 308 source: Read Commands from a File Usage: source [-nh-] filename Commands are executed just as if they were typed directly in to this thread of Hamilton C shell and can change local variables and current directory settings. (This differs from typing the name of a C shell script file as a command; if you do that, a separate thread is created.) Options: -n No Execute (Just load the history list.) -h Help. -- End of options. split: Split a Large File into Chunks Usage: split [-bhs<size>-] [ infile [prefix] ] split breaks up a large file into chunks, written to a series of output files formed of the prefix plus a .nnn extension, where nnn is a 3-digit decimal number. The default prefix is 'chunk'. Each chunk will be of the specified number of lines or bytes. If only one operand is given, it's assumed to be the input filename unless -s is specified. Options: -h Help. (This screen.) -b Count bytes. (Default is lines.) -s Stdin is split. (Implied if no files are specified.) -<size> Chunk size. (Defaults are 3000 lines/300000 bytes.) -- End of options. Page 309 Help strings: Extract ascii strings from a file Usage: strings [-habetqvlodx-] [-<min>] [-r<radix>] [ file1 file2 ... ] strings will search for any occurrences of ascii text in the files you give it. The presumption is that the files are mostly binary and perhaps quite large, making it impractical to look at them directly. A string is normally defined as 4 or more printable ascii characters terminated by a Null, CarriageReturn, a NewLine or a CarriageReturn- NewLine combination. All the white space characters are considered printable and are included in the length count except when they terminate a string. (To C programmers, these printable ascii characters are the isprint() and isspace() characters.) If you specify a series of files, they're searched one after the other, each one introduced by name unless you specify Quiet mode. Each string that's found is listed on a separate line. Note that if a particular string contains NewLine or CarriageReturn characters, it will be displayed as a series of (possibly) very short substrings, one per line. Options: -h Help. (This screen.) -<min> Minimum string length to report, specified as a decimal integer. -a Any string, even if not terminated with a line ending or a null character. -t Trim leading white space from each string. -b Discard strings containing only white space. -e European characters (accented alphabetics and European punctuation) will be considered as ordinary printable text. -n Control characters other than Tab, CarriageReturn and NewLine will be considered to be string terminators just like the null character. -q Quiet mode. Don't announce the name of each file as it's read. -v Verbose. Paste the name of the file in which it occurs onto the front of each string. -l Long mode. Show where each string occurs, counting bytes from the beginning of the file. The radix used can be explicitly Page 310 chosen with -o, -d, -x, or -r; it defaults to the value specified by the RADIX environmental variable if defined or 16 otherwise. -o Octal offsets. -d Decimal offsets. -x Hex offsets shown. -r<radix> User-specified radix. -- End of options. sum: Checksum the contents of a file Usage: sum [-rxh-] [ file1 file2 ... ] sum checksums the contents of each of the files you specify, writing the results to stdout along with a count of the number of 512-byte blocks it read (including any partial blocks.) If no files are given, sum reads from stdin. sum is typically used to validate a file communicated over a possibly noisy communications line. sum treats the characters it reads as 8-bit unsigned integers and normally just adds them together to form a 16-bit unsigned result. Overflows are ignored. Options: -r Rotated checksum. Rotate the accumulated checksum right one bit position before adding each character. -x Xor'ed checksum. For each new character, c, the checksum, i, is calculated as i += (i << 1) ^ c. -h Help. (This screen.) -- End of options. (The default and rotated checksums are the same as those calculated by the UNIX System V sum command; the xor checksum is unique to this implementation.) Page 311 Help tabs: Expand/Unexpand Tabs Usage: tabs [-hua-] [-<tabs>][ file1 file2 ... ] tabs expands tab characters into spaces or, if -u is specified, unexpands spaces into tabs as it copies the input files to stdout. If no files are given, tabs reads from stdin. If multiple files are given, they're concatenated one after the other to stdout. When unexpanding, only leading white space is normally converted to tabs. If -a is specified, tabs are inserted anywhere they would replace two or more characters. Options: -h Help. (This screen.) -u Unexpand tabs. -a Unexpand all tabs. -<tabs> Tab settings to use for viewing text. Default is to use value given by the TABS environment variable or, if that's undefined, to assume tabstops every 8 characters. If desired, a list of tabstops can specified, separated by commas; the difference between the last two tabs given is used a standard increment for following tabs. -- End of options. Page 312 tail: Copy the last few lines or bytes of a file to Stdout Usage: tail [-hcfnq-] [-i<sec>] [m<msec>] [-+<start>] [-t<tabs>] [ file1 file2 ... ] tail copies the last part of the file you specify onto stdout. You may specify where to begin copying in either lines or bytes measured from either the beginning or the end of the file. If no file is given, tail reads from stdin. If several files are given, each is announced unless you specify quiet mode. Options: -h Help. (This screen.) -c Count characters. (Default is lines.) -f Follow. At end of file, go into an endless loop, sleeping for a second, then waking up to see if more data's been added. (Use ^C to exit.) The follow option is not valid if more than one file is specified and is ignored if data is being read from a pipe. -i<sec> Interval in seconds between checking for more data if -f option is used. (If the interval specified is greater than one second, tail will temporarily drop back to a one second interval anytime it finds new data when it does wake up.) -m<msec> Interval in milliseconds between checking for more data if -f option is used. -<start> Starting point, relative to the end of the file. (Default is last 10 lines or 512 bytes.) +<start> Starting point, relative to the start of the file. -t<tabs> Tab settings to use for viewing text. (Default is to use value given by the TABS environment variable or, if that's undefined, to do no tab expansion.) -n No tab expansion. -q Quiet mode. Don't announce the name of each file it's read. -- End of options. Page 313 Help tar: Read/Write UNIX Tape Archive (tar) Format Files Usage: tar [-acCtMxXh FLvqs!rRfBQWZ-] [-d dir] [-m map] [-g hours] [-O offset] [-E endset] [-b sex] [ tarfile ] [ file1 file2 ... ] tar is used to read or write a simple archive format popular for exchanging files between dissimilar machines. tar normally expects the archive to be in a file specified by the tarfile operand. When listing or extracting files, the following file names are considered to be in the name space of what's in the archive and wildcards should not be used. When adding files, the names are in the user's normal file name space. When extracting files, this version of tar incorporates logic to interactively crunch up a filename in the archive into something legal on an OS/2 or NT filesystem. If -F is specified (or you're using OS/2 1.1), FAT naming rules are enforced. Otherwise, HPFS rules are assumed. tar lists these renamings in a .map file. tar also incorporates logic to automatically convert between the \n line ending used in an archive and the \r\n line endings used under OS/2 or NT unless the file appears to be binary. Basic Commands: -a Add files to the end of the archive. -c Copy the specified files in the archive to stdout. -C Copy entire tar segments (including headers and any padding) to stdout. After the last segment, write two blocks of zeros to mark the end of a tar archive. (If you intend to concatenate archive, use the -Z option to suppress writing the trailing blocks of zeros.) -t List table of contents (the default). List the files in the archive. -M Just build the mapfile; don't extract anything. -x Extract files from the archive. Default is all files in the archive. (Do not use wildcarding.) -X Extract everything EXCEPT the specified files from the archive. -h Help. (This screen.) Page 314 Page 315 Help Basic Options: -F FAT filesystem naming. (Automatically chosen if the OS/2 release level < 1.2.) -L Long listing similar to ls -L showing the attributes, timestamp and length of each file in the archive. -v Verbose. Also show the offset of each file from the beginning of the archive. -q Quiet. tar normally prints the head of each file as it's extracted (-x) or added (-a) to the archive. This option turns that off. -s Read the archive from stdin when listing table of contents or extracting. Write the archive to stdout when adding files. (Implies non-interactive.) -! Non-interactive. Files are renamed as necessary for OS/2 or NT conventions. (Particularly useful with -M when trying to read a new, large archive file.) -r CarriageReturn/NewLine expansion is turned off. (Default is normally to convert between \n in the archive and \r\n under OS/2 or NT unless the file appears to be binary.) -R CarriageReturn/NewLine expansion is forced ON, even for files that appear to be binary. -- End of options. Advanced Options: -d dir Default destination drive and directory when extracting files. -m map Specific filename to be used for showing mappings from names in the archive to names used on OS/2 or NT. (Default is to paste a .map extension onto the name of the tar file; if -s is specified, no map file is used unless -m is given.) -f Fullpath option. Put the full pathname (minus any disk prefix) specified on the command line into the archive header when adding. (In this context, the full path means the full name given on the command line, not the fully-qualified name starting from the root directory.) When extracting, use the full pathname given in the header to determine where the files will go. -g hours The number of hours GMT is ahead of the local zone, e.g., 5 hours in New York or 8 hours in California. U.S. Page 316 daylight savings is assumed in the summer months. (OS/2 only.) Page 317 Help -G hours Same as -g, but without daylight savings adjustments. (Under OS/2, if neither -g nor -G is specified, tar looks for a TZ variable in the environment; if it's not defined, tar ignores the difference between local time and GMT used in the archive. Under Windows NT, the -g and -G options and the TZ variable are unnecessary since the system keeps track of the difference between local time and GMT.) -O offset Offset at which to start reading the archive file. Given in bytes from beginning of the file. -E endset Offset at which to stop reading the archive file. -b sex Byte sex in the archive: abcd (default), badc, cdab or dcba. -B Autosense byte sex when reading. -Q Very Quiet. tar normally warns of any garbled sections that it skipped; this turns off those warnings also. -W Warnings. Show just the files that can't be extracted to OS/2 or NT because of their file types. (Always shown in bright red.) -Z Suppress writing the trailing blocks of zeros normally written following the last of the segments extracted with the -C option. (Useful for concatenating segments extracted from several separate archives.) File Format: Tar files are organized as a series of 512-byte blocks. Individual files always start on a block boundary with a header block followed by the uncompressed data in the file. At the end of the file are two blocks filled with binary zeros. The header has the following format: typedef struct { char name[100], mode[8], userid[8], groupid[8], filesize[12], timestamp[12], checksum[8], linkflag, linkname[100]; Page 318 unused_chars[255]; } header; Everything is in ascii with nulls and spaces to punctuate the fields. Numbers are always in octal. The mode, user and group ids aren't meaningful on OS/2 and NT and are ignored when extracting and just filled in with read/write for owner, owned by root when adding. The timestamp is in seconds since Jan 1 00:00:00 GMT 1970. The checksum is calculated as if the field contained spaces. The linkflag tells the file type, reported in the long listing as one of the following: - Normal File D Directory L Link (not a separate file, just another name for one that already exists) S Symbolic Link C Character Device B Block Device F FIFO Under OS/2 and NT, only the normal files and directories have any meaning. Directories are highlighted. The other file types are reported in bright red but otherwise ignored. Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black DIRECTORIES Directories Bright FOREIGNFILES Filetypes not supported Bright Red by OS/2 and NT Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a Page 319 Help value, it's considered transparent and inherits the color underneath it. DIRECTORIES and FOREIGNFILES inherit from COLORS. Page 320 tee: Copy Stdin to Stdout and to Each File Specified Usage: tee [ -a- ] file1 [ file2 ... ] tee is a ``pipe-fitting'' utility for snapshotting the data passing through the middle of a pipeline. Options: -a Append to any output files that already exist instead of truncating and overwriting them. -h Help. -- End of Options. touch: Create File or Set Modification Time Usage: touch [-rfc-] [ mmddhhmm[yy] ] pathname1 [ pathname2 ... ] touch sets the timestamp on a file to the current or specified date and time. If the file doesn't exist, the normal action is to create it. The OS/2 1.1 kernel ignores attempts to change a directory timestamp. Options: mmddhhmmyy Month, Day, Hour, Minutes and Year in decimal. -r Recursively touch contents of directories. -f Force Read-only files to be touched also. -c File is Not created if it doesn't already exist. -h Help. -- End of options. Page 321 Help tr: Translate Characters Filter Usage: tr [-cdsnh-] [ string1 [string2] ] tr is used to perform simple character substitutions as it copies data from stdin to stdout. Individual characters in string1 are mapped to the corresponding characters of string2. If string2 is too short, it is padded by duplicating its last character. In either string, the minus sign can be used to indicate a range of characters. Here's an example which creates a list of all the words in file1, one per line, in file2, where a word is taken as a maximal string of alphabetics. (The ^n character is expanded by the C shell into a newline character.) % tr -csn A-Za-z ^n <file1 >file2 Options: -h Help. (This screen.) -c Complement the set of characters in string1. -d Delete any occurrences of the characters in string1. (If present, string2 is ignored.) -s Squeeze all strings of repeated output characters in string2 to single characters. -n Normalize line endings. Ensure that every line ends with \r\n. Fixup any \r or \n by itself or any reversed \n\r character pair. When squeezing, normalization also causes repeated \r\n sequences to be squeezed if either \r or \n is in string2. -- End of options. Page 322 unhash: Turn off Path Hashing Usage: unhash [-h-] Normally, a hashing mechanism is used in an attempt to speed up searches of the path directories. If you're performing system administration work, moving files in the path directories, the hash mechanism may not always reflect the latest changes you've made. The unhash command can be used to turn hashing off, setting nohashing = 1. (See also the rehash and hashstat commands.) Options: -h Help. -- End of options. Page 323 Help uniq: Report unique lines in text files Usage: uniq [-hbcdiuw-] [ file1 file2 ...] uniq does a quick, simple string comparison of adjacent lines in text files, normally just discarding any duplicates as it copies its input to stdout. There are some diff-style options for ignoring upper-/lower-case differences or treating white spaces of any length as equal, etc. Also, you can optionally choose to list only the lines that occur just once or only those that have duplicates. If several files are given, the effect is the same as if they were pasted together, one right after another into one long file. Options: -h Help. -b Blank spaces of any length compare equal. Ignore any leading or trailing white space on each line. -c Preface each line with a count of the number of times it occurred. -d Duplicates. Only the lines which have at least one duplicate are reported. -i Ignore character case. -u Unique lines. Only the lines which occur only once are reported. -w White space is ignored totally. -- End of options. verify: Turn Write Verification Mode On or Off Usage: verify [-h-] [ mode ] When verification mode is turned on, the system will always verify that any data written to a disk can be read back. The mode can be specified as 0 or off, the default, or 1 or on. If no arguments are given, verify simply reports the current mode. Under NT, verify is always on. Options: -h Help. -- End of options. Page 324 vol: List Volume Labels Usage: vol [-ach] [ disk1 disk2 ... ] vol reports the volume label information on each of the specified disks. If no disks are specified, vol looks for a DRIVEMASK environmental variable that can be used to mask off just the drive you want reported. The DRIVEMASK is specified as a list of drive letters; ranges are allowed. Otherwise, all the partitions beginning with c: are reported. The current disk's label information is highlighted. This command is normally stored in the file vl.exe and invoked via an alias so it can be used from cmd.exe without colliding with the internal cmd.exe vol function. Options: -a If no disks are specified, report on all disks. -c If no disks are specified, report on just the current disk. -h Help. -- End of options. Colors: You may set your own choices for screen colors using these environmental variables: Name Use Default COLORS Normal screen colors White on Black HIGHLIGHT Current disk Bright Colors recognized are black, red, green, yellow, blue, magenta (or red blue), cyan (or blue green) or white. Foreground colors may also be bright or blink. The names of the colors and the words bright, blink and on may be in either upper or lower or mixed case but the names of the environmental variables themselves must be all upper case. Either or both the foreground and background colors may be specified; if you don't specify a value, it's considered transparent and inherits the color underneath it. HIGHLIGHT inherits from COLORS. Page 325 Help wait: Wait for Children to Complete Usage: wait [-h-] Sleep until a child thread or process completes or until an interrupt occurs. Options: -h Help. -- End of options. wc: Count Words (and lines and characters) Usage: wc [ -lwr ] [ file1 file2 ... ] wc prints counts all the lines, words and/or characters in each of the files specified, and totals for the whole list. If no files are specified, it counts stdin. Options: -l Count lines -w Count words -c Count characters -h Help. -- End of options. The default is -lwc. whereis: Find where executable files are located Usage: whereis command whereis is a self-loading procedure that searches all the directories on the path, looking for a .csh, .exe, .com, or .cmd file corresponding to the command specified. All occurrences are printed. Page 326 xd: Hex dump a file to Stdout Usage: xd [-hbwlFD Zdxor nNq-] [-r<radix>] [-O <offset>] [-E <endset>] [-L[<items>]] [ file1 file2 ... ] xd dumps its input, presumed to be in binary, in variety of formats, the default being hex. If more than one file is given, each is dumped in sequence. If no files are specified, xd reads from stdin. Sequences of lines containing the same data are collapsed out and replaced by an asterisk. Options: -h Help. (This screen.) Basic display formats: -b Bytes. (Default.) -w 16-bit words. -l 32-bit long words. -F Short 4-byte floating point. Floating point values are always displayed in decimal. -D Double-precision 8-byte floating point. -Z Suppress leading zeros. Normally, leading zeros are shown except when displaying in decimal. Radix to be used for offsets and data: -d Decimal (unsigned). -x Hex. -o Octal. -r<radix> User-specified radix. If a radix < 8 is chosen, offsets are always shown in hex. Other options: -O <offset> Offset at which to begin dumping. -E <endset> Offset at which to stop dumping. -L[<items>] Number of items (bytes, words, etc.) to dump. If -L is specified, the default is one. -n No ascii column. -N No offset column. -q Quiet mode. Don't announce the name of each file as it's read. -v Verbose. Show lines of repeated data. -- End of options. Page 327