Concepts Glossary 142 Getting Started Guide bash bash is the standard (default) command interpreter for Linux. UNIX and Linux systems have many possible command line interpreters, all called shells. A shell is equivalent to the DOS command prompt, which uses the COMMAND.COM program to provide the ability to execute commands, run scripts (batch files in DOS) and similar tasks. The bash shell in Linux is much more powerful than a DOS command prompt. bash provides a full scripting language, ability to control multiple simultaneous running applications, and many other features. You can learn about these by run- ning man bash. If you’re familiar with a different shell because of experience on a different Linux or UNIX system, you can change your user account to use that shell (for example, tch or csh). To do this, change the name of the shell program by your username in the /etc/passwd file or using a graphical user management tool. Boot diskette When you begin installing Linux, you must give control of your computer to the installation program. Because many operating systems launch programs without releasing full control of the computer, you sometimes must boot your computer from a diskette that can start the Linux installation program “from scratch,” with- out any other operating system starting first on your computer. The boot disk is a copy of a portion of the Linux installation program that starts up your computer and begins the installation process. If your computer can boot directly from CD-ROM, or if you start the installation process from another oper- ating system (as provided by the options in the Windows components of Open- Linux 2.2), then a boot disk is normally not necessary. If you need a boot diskette, you can create one using the procedure described in Chapter 2. Case sensitivity In many programs and operating systems, it doesn’t matter whether you use upper case letters or lower case letters to name files or enter commands. Linux, and almost every application or tool you use within Linux, is case sensitive. This can be confusing at first. For example, the command to change to a new directory is cd. If you have the CAPS-LOCK key set and enter this command: CD ..