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NAME ed, red - text editor SYNTAX ed [-] [-pstring] [file] red [-] [file] DESCRIPTION The ed text editor is the standard text editor. If the file argument is given, ed simulates an e command (see below) on the named file; that is to say, the file is read into ed's buffer so that it can be edited. The optional - suppresses the printing of character counts by e, r, and w commands, of diagnostics from e and q commands, and of the ! prompt after a !shell command. The -p option allows the user to specify a prompt string. The ed text editor operates on a copy of the file it is editing; changes made to the copy have no effect on the file until a w (write) command is given. The copy of the text being edited resides in a temporary file called the buffer. There is only one buffer. The red text editor is a restricted version of ed. It only allows editing of files in the current directory. It prohi- bits executing shell commands via !shell command. Attempts to bypass these restrictions result in an error message (restricted shell). NOTE While inputting text, tab characters are expanded to every eighth column as is the default. Commands to ed have a simple and regular structure: zero, one, or two addresses followed by a single-character com- mand, possibly followed by parameters to that command. These addresses specify one or more lines in the buffer. Every command that requires addresses has default addresses, so that the addresses can frequently be omitted. In general, only one command appears on a line. Certain commands allow the input of text. This text is placed in the appropriate place in the buffer. While ed is accepting text, it is said to be in input mode. In input mode, no commands are recognized; all input is merely collected. Input mode is exited by typing a period (.) alone at the beginning of a line. The ed text editor supports a limited form of regular expression notation; regular expressions are used in addresses to specify lines and in some commands (for exam- ple, s) to specify portions of a line that are to be substi- tuted. A regular expression (RE) specifies a set of charac- ter strings. A member of this set of strings is said to be matched by the RE. The REs allowed by ed are constructed as follows: The following one-character REs match a single character: 1.1 An ordinary character (not one of those discussed in 1.2 below) is a one-character RE that matches itself. 1.2 A backslash (\) followed by any special character is a one-character RE that matches the special character itself. The special characters are: a. ., *, [, and \ (period, asterisk, left square bracket, and backslash, respectively), which are always special, except when they appear within square brackets ([]; see 1.4 below). b. ^ (caret or circumflex), which is special at the beginning of an entire RE (see 3.1 and 3.2 below), or when it immediately follows the left of a pair of square brackets ([]) (see 1.4 below). c. $ (currency symbol), which is special at the end of an entire RE (see 3.2 below). d. The character used to bound (that is, delimit) an entire RE, which is special for that RE (for example, see how slash (/) is used in the g command, below.) 1.3 A period (.) is a one-character RE that matches any character except new-line. 1.4 A non-empty string of characters enclosed in square brackets ([]) is a one-character RE that matches any one character in that string. If, however, the first character of the string is a circumflex (^), the one-character RE matches any character except new- line and the remaining characters in the string. The ^ has this special meaning only if it occurs first in the string. The minus (-) may be used to indicate a range of consecutive ASCII characters; for example, [0-9] is equivalent to [0123456789]. The - loses this special meaning if it occurs first (after an initial ^, if any) or last in the string. The right square bracket (]) does not terminate such a string when it is the first character within it (after an initial ^, if any). For example, []a-f] matches either a right square bracket (]) or one of the letters a through f inclusive. The four characters listed in 1.2.a above stand for themselves within such a string of characters. The following rules may be used to construct REs from one- character REs: 2.1 A one-character RE is a RE that matches whatever the one-character RE matches. 2.2 A one-character RE followed by an asterisk (*) is a RE that matches zero or more occurrences of the one- character RE. If there is any choice, the longest leftmost string that permits a match is chosen. 2.3 A one-character RE followed by \{m\}, \{m,\}, or \{m,n\} is a RE that matches a range of occurrences of the one-character RE. The values of m and n must be non-negative integers less than 256; \{m\} matches exactly m occurrences; \{m,\} matches at least m occurrences; \{m,n\} matches any number of occurrences between m and n inclusive. Whenever a choice exists, the RE matches as many occurrences as possible. 2.4 The concatenation of REs is a RE that matches the concatenation of the strings matched by each com- ponent of the RE. 2.5 A RE enclosed between the character sequences $ and $ is a RE that matches whatever the unadorned RE matches. 2.6 The expression \n matches the same string of charac- ters as was matched by an expression enclosed between $ and $ earlier in the same RE. Here n is a digit; the sub-expression specified is that beginning with the n-th occurrence of $ counting from the left. For example, the expression ^\(.*$\1$ matches a line consisting of two repeated appearances of the same string. Finally, an entire RE may be constrained to match only an initial segment or final segment of a line (or both): 3.1 A circumflex (^) at the beginning of an entire RE constrains that RE to match an initial segment of a line. 3.2 A currency symbol ($) at the end of an entire RE con- strains that RE to match a final segment of a line. The construction ^entire RE$ constrains the entire RE to match the entire line. The null RE (for example, //) is equivalent to the last RE encountered. See also the last paragraph before FILES below. To understand addressing in ed it is necessary to know that at any time there is a current line. Generally speaking, the current line is the last line affected by a command; the exact effect on the current line is discussed under the description of each command. Addresses are constructed as follows: 1. The character . addresses the current line. 2. The character $ addresses the last line of the buffer. 3. A decimal number n addresses the n-th line of the buffer. 4. 'x addresses the line marked with the mark name char- acter x, which must be a lower-case letter. Lines are marked with the k command described below. 5. A RE enclosed by slashes (/) addresses the first line found by searching forward from the line following the current line toward the end of the buffer and stopping at the first line containing a string match- ing the RE. If necessary, the search wraps around to the beginning of the buffer and continues up to and including the current line, so that the entire buffer is searched. See also the last paragraph before FILES below. 6. A RE enclosed in question marks (?) addresses the first line found by searching backward from the line preceding the current line toward the beginning of the buffer and stopping at the first line containing a string matching the RE. If necessary, the search wraps around to the end of the buffer and continues up to and including the current line. See also the last paragraph before FILES below. 7. An address followed by a plus sign (+) or a minus sign (-) followed by a decimal number specifies that address plus (respectively minus) the indicated number of lines. The plus sign may be omitted. 8. If an address begins with + or -, the addition or subtraction is taken with respect to the current line. For example, -5 is understood to mean .-5. 9. If an address ends with + or -, then 1 is added to or subtracted from the address, respectively. As a consequence of this rule and of rule 8 immediately above, the address - refers to the line preceding the current line. (To maintain compatibility with ear- lier versions of the editor, the character ^ in addresses is entirely equivalent to -.) Moreover, trailing + and - characters have a cumulative effect, so -- refers to the current line less 2. 10. For convenience, a comma (,) stands for the address pair 1,$, while a semicolon (;) stands for the pair .,$. Commands may require zero, one, or two addresses. Commands that require no addresses regard the presence of an address as an error. Commands that accept one or two addresses assume default addresses when an insufficient number of addresses is given; if more addresses are given than such a command requires, the last one(s) are used. Typically, addresses are separated from each other by a comma (,). They may also be separated by a semicolon (;). In the latter case, the current line (.) is set to the first address, and only then is the second address calculated. This feature can be used to determine the starting line for forward and backward searches (see rules 5. and 6. above). The second address of any two-address sequence must correspond to a line that follows, in the buffer, the line corresponding to the first address. In the following list of ed commands, the default addresses are shown in parentheses. The parentheses are not part of the address; they show that the given addresses are the default. It is generally illegal for more than one command to appear on a line. However, any command (except e, f, r, or w) may be suffixed by l, n or p, in which case the current line is either listed, numbered or printed, respectively, as dis- cussed below under the l, n and p commands. (.)a <text> . The append command reads the given text and appends it after the addressed line; . is left at the last inserted line, or, if there were none, at the addressed line. Address 0 is legal for this com- mand: it causes the ``appended'' text to be placed at the beginning of the buffer. The maximum number of charac- ters that may be entered from a terminal is 256 per line (including the new line character). (.)c <text> . The change command deletes the addressed lines, then accepts input text that replaces these lines; . is left at the last line input, or, if there were none, at the first line that was not deleted. (.,.)d The delete command deletes the addressed lines from the buffer. The line after the last line deleted becomes the current line; if the lines deleted were originally at the end of the buffer, the new last line becomes the current line. e file The edit command causes the entire con- tents of the buffer to be deleted, and then the named file to be read in; . is set to the last line of the buffer. If no file name is given, the currently- remembered file name, if any, is used (see the f command). The number of characters read is typed; file is remem- bered for possible use as a default file name in subsequent e, r, and w commands. If file is replaced by !, the rest of the line is taken to be a shell, sh(1), command whose output is to be read. Such a shell command is not remembered as the current file name. See also DIAGNOSTICS below. E file The edit command is like e, except that the editor does not check to see if any changes have been made to the buffer since the last w command. f file If file is given, the file-name command changes the currently-remembered file name to file; otherwise, it prints the currently-remembered file name. (1,$)g/RE/command list In the global command, the first step is to mark every line that matches the given RE. Then, for every such line, the given command list is executed with . initially set to that line. A single command or the first of a list of com- mands appears on the same line as the global command. All lines of a multi- line list except the last line must be ended with a \; a, i, and c commands and associated input are permitted; the . terminating input mode may be omitted if it would be the last line of the command list. An empty command list is equivalent to the p command. The g, G, v, and V commands are not permitted in the command list. See also RESTRICTIONS and the last paragraph before FILES below. (1,$)G/RE/ In the interactive Global command, the first step is to mark every line that matches the given RE. Then, for every such line, that line is printed, . is changed to that line, and any one com- mand (other than one of the a, c, i, g, G, v, and V commands) may be input and is executed. After the execution of that command, the next marked line is printed, and so on; a new-line acts as a null command; an & causes the re- execution of the most recent command executed within the current invocation of G. Note that the commands input as part of the execution of the G command may address and affect any lines in the buffer. The G command can be terminated by an interrupt signal (ASCII DEL or BREAK). h The help command gives a short error message that explains the reason for the most recent ? diagnostic. H The help command causes ed to enter a mode in which error messages are printed for all subsequent ? diagnostics. It will also explain the previous ? if there was one. The H command alter- nately turns this mode on and off; it is initially off. (.)i <text> . The insert command inserts the given text before the addressed line; . is left at the last inserted line, or, if there were none, at the addressed line. This command differs from the a command only in the placement of the input text. Address 0 is not legal for this command. The maximum number of characters that may be entered from a terminal is 256 per line (including the new line charac- ter). (.,.+1)j The join command joins contiguous lines by removing the appropriate new-line characters. If exactly one address is given, this command does nothing. (.)kx The mark command marks the addressed line with name x, which must be a lower-case letter. The address 'x then addresses this line; . is unchanged. (.,.)l The list command prints the addressed lines in an unambiguous way: a few non- printing characters (for example, tab, backspace) are represented by (hope- fully) mnemonic overstrikes, all other non-printing characters are printed in octal, and long lines are folded. An l command may be appended to any other command other than e, f, r, or w. (.,.)ma The B. move command repositions the addressed line(s) after the line addressed by a. Address 0 is legal for a and causes the addressed line(s) to be moved to the beginning of the file; it is an error if address a falls within the range of moved lines; . is left at the last line moved. (.,.)n The number command prints the addressed lines, preceding each line by its line number and a tab character; . is left at the last line printed. The n command may be appended to any other command other than e, f, r, or w. (.,.)p The print command prints the addressed lines; . is left at the last line printed. The p command may be appended to any other command other than e, f, r, or w; for example, dp deletes the current line and prints the new current line. P The editor will prompt with a * for all subsequent commands. The P command alternately turns this mode on and off; it is initially off. q The quit command causes ed to exit. No automatic write of a file is done (but see DIAGNOSTICS below). Q The editor exits without checking if changes have been made in the buffer since the last w command. ($)r file The read command reads in the given file after the addressed line. If no file name is given, the currently-remembered file name, if any, is used (see e and f commands). The currently-remembered file name is not changed unless file is the very first file name mentioned since ed was invoked. Address 0 is legal for r and causes the file to be read at the beginning of the buffer. If the read is successful, the number of characters read is typed; . is set to the last line read in. If file is replaced by !, the rest of the line is taken to be a shell (sh(1)) command whose output is to be read. For example, "$r !ls" appends current directory to the end of the file being edited. Such a shell command is not remembered as the current file name. (.,.)s/RE/replacement/ or (.,.)s/RE/replacement/g The substitute command searches each addressed line for an occurrence of the specified RE. In each line in which a match is found, all (non-overlapped) matched strings are replaced by the replacement if the global replacement indicator g appears after the command. If the global indicator does not appear, only the first occurrence of the matched string is replaced. It is an error for the substitution to fail on all addressed lines. Any character other than space or new-line may be used instead of / to delimit the RE and the replacement; . is left at the last line on which a substitution occurred. See also the last paragraph before FILES below. An ampersand (&) appearing in the replacement is replaced by the string matching the RE on the current line. The special meaning of & in this context may be suppressed by preceding it by \. As a more general feature, the charac- ters \n, where n is a digit, are replaced by the text matched by the n-th regular subexpression of the specified RE enclosed between $ and $. When nested parenthesized subexpressions are present, n is determined by counting occurrences of \( starting from the left. When the character % is the only character in the replacement, the replacement used in the most recent sub- stitute command is used as the replace- ment in the current substitute command. The % loses its special meaning when it is in a replacement string of more than one character or is preceded by a \. A line may be split by substituting a new-line character into it. The new- line in the replacement must be escaped by preceding it by \. Such substitution cannot be done as part of a g or v com- mand list. (.,.)ta This command acts just like the m com- mand, except that a copy of the addressed lines is placed after address a (which may be 0); . is left at the last line of the copy. u The undo command nullifies the effect of the most recent command that modified anything in the buffer, namely the most recent a, c, d, g, i, j, m, r, s, t, v, G, or V command. (1,$)v/RE/command list This command is the same as the global command g except that the command list is executed with . initially set to every line that does not match the RE. (1,$)V/RE/ This command is the same as the interac- tive global command G except that the lines that are marked during the first step are those that do not match the RE. (1,$)w file The write command writes the addressed lines into the named file. If the file does not exist, it is created with mode 666 (readable and writable by everyone), unless your umask setting (see sh(1)) dictates otherwise. The currently- remembered file name is not changed unless file is the very first file name mentioned since ed was invoked. If no file name is given, the currently- remembered file name, if any, is used (see e and f commands); . is unchanged. If the command is successful, the number of characters written is typed. If file is replaced by !, the rest of the line is taken to be a shell (sh(1)) command whose standard input is the addressed lines. Such a shell command is not remembered as the current file name. ($)= The line number of the addressed line is typed; . is unchanged by this command. !shell command The remainder of the line after the ! is sent to the UNIX System shell (sh(1)) to be interpreted as a command. Within the text of that command, the unescaped character % is replaced with the remem- bered file name; if a ! appears as the first character of the shell command, it is replaced with the text of the previ- ous shell command. Thus, !! will repeat the last shell command. If any expan- sion is performed, the expanded line is echoed; . is unchanged. (.+1)<new-line> An address alone on a line causes the addressed line to be printed. A new- line alone is equivalent to .+1p; it is useful for stepping forward through the buffer. If an interrupt signal (ASCII DEL or BREAK) is sent, ed prints a ? and returns to its command level. Some size limitations: 512 characters per line, 256 charac- ters per global command list, 64 characters per file name, and 128K characters in the buffer. The limit on the number of lines depends on the amount of user memory: each line takes 1 word. When reading a file, ed discards ASCII NUL characters and all characters after the last new-line. Files (for example, a.out) that contain characters not in the ASCII set (bit 8 on) cannot be edited by ed. If the closing delimiter of a RE or of a replacement string (for example, /) would be the last character before a new- line, that delimiter may be omitted, in which case the addressed line is printed. The following pairs of commands are equivalent: s/s1/s2 s/s1/s2/p g/s1 g/s1/p ?s1 ?s1? RESTRICTIONS A ! command cannot be subject to a g or a v command. The ! command and the ! escape from the e, r, and w commands cannot be used if the the editor is invoked from a res- tricted shell. For further information, see sh(1). The sequence \n in a RE does not match a new-line character. The l command mishandles DEL. DIAGNOSTICS ? for command errors. ?file for an inaccessible file. (use the help and Help commands for detailed explanations). If changes have been made in the buffer since the last w command that wrote the entire buffer, ed warns the user if an attempt is made to destroy ed's buffer via the e or q commands: it prints ? and allows one to continue editing. A second e or q command at this point will take effect. The - command-line option inhibits this feature. FILES /tmp/e# temporary; # is the process number. ed.hup work is saved here if the terminal is hung up. SEE ALSO grep(1), sed(1), sh(1), stty(1),