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Command Shells

The command shell is the program that handles your interaction with the system. Unless you requested otherwise when you were given your account, your login shell is tcsh. The tcsh program is an enhanced version of the csh program, which is described in some Unix texts. The tcsh shell differs from the Bourne shell sh in some respects. Since most texts assume you are using sh, you may find that some commands do not work as stated. Most of the differences have to do with advanced features, so beginners should not have any difficulties. Full documentation of csh, tcsh, sh and bash (an enhanced version of sh) can be found in the online manual pages, or any comprehensive book on Unix.

The main advantages of the tcsh program are its command and filename completion feature, and the ability to recall and edit commands. To use command and filename completion, type the beginning characters of the desired word, then hit the tab key. If only one word matching what you typed is found, the complete name will be filled in. Otherwise you will be prompted with the possible completions. You can recall earlier commands using the up-arrow key, and you can edit a command line by using the left- and right-arrow keys, the delete key, and typing replacement text. You can also edit the command line using Emacs-style commands.

Other shells: The standard Bourne shell sh is the original Unix command shell. An improved version which includes command recall and editing is called bash (Bourne-again shell).