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Shell Facts

The Linux shell is the Command Line Interface (CLI) or Text User Interface (TUI) that administrators use to control a Linux operating system. Users and programs use the shell to send commands to the system. A shell might be opened inside a Graphical User Interface (GUI), or might be the sole method used to run the computer.

Although most Linux distributions now include a graphical interface, and many administration tools have been converted to a graphical format, many tasks are best performed from the command prompt. In addition, while graphical elements vary between distributions, shell commands are more likely to be consistent between distributions.

The following table describes many common shell types:

Shell Type Description
bash The Bourne-again shell (bash) is the standard shell used in most Linux computers. It uses commands similar to a UNIX shell. Bash includes features such as:
  • Command completion when pressing the tab key
  • Command history
  • Improved arithmetic functions
sh The Bourne shell is an earlier version of the Bash shell, and is similar in many ways. Sh is the original shell created by Steve Bourne.
ksh The Korn shell was developed by David Korn. Ksh has scripting features not found in bash.
csh The C-shell uses syntax similar to syntax used in the C programming language.
tcsh The tcsh shell is an improved version of csh. It offers command line editing and completion features not available with csh.

Despite their differences, all shells share some common characteristics: