The C shell (csh) is a Unix and Linux shell that was developed in the late 1970s. It is a command-line interface (CLI) that allows users to interact with the operating system using text-based commands.
Like other Unix and Linux shells, the C shell provides features such as command history, command line editing, and built-in commands for performing common tasks. It also includes features such as variables, control structures (such as if and while), and aliases, which allow users to define their own commands and customize their shell environment.
One of the main differences between the C shell and other shells, such as the Bourne shell (sh) and the Bash shell (bash), is the syntax of the commands and the programming constructs. The C shell uses a syntax that is more similar to the C programming language, which can make it more familiar to programmers who are already familiar with C.
The C shell is not as widely used as some other shells, but it is still available on many Unix and Linux systems and can be a useful tool for users who prefer its syntax and features.