Unix shell

A Unix shell, also called terminal or console, is a program that accepts Unix commands from the keyboard and executes them. These commands can be installed programs, for example:

• ls to list files
• cp to copy files
• man to get more information on commands

Three Unix shells, in this case zsh, bash, and ksh shell in Linux (click to enlarge)

The commands do not need to come from the keyboard. They will, generally speaking, come from stdin. A Unix shell is a command line interface made especially for the control of a Unix system. There are different Unix shells, most notably bash, sh, C Shell and zsh. Their syntax is similar, for example the following dialog to find out your CPU type would be possible with all of them:

# cat /proc/cpuinfo | grep --max-count=1 "model name"
model name      : Intel(R) Core(TM) i7 CPU         860  @ 2.80GHz