What Is the C Shell

Computer History Notes - Herong's Tutorial Notes

∟1978 - The C Shell Developed by Bill Joy

∟What Is the C Shell

This section provides a quick introduction of the C shell which offers a easier command syntax than Bourne shell for C programmers.

What Is C Shell? - C Shell is a Unix shell introduced by Bill Joy in 1978. The C shell was derived from the Thompson shell. It has a syntax modeled after the C programming language.

The C shell has the following main features:

Alias Substitution - The ability to define command aliases and use them in new commands.
Arithmetic and Boolean Expressions - The ability to evaluate arithmetic and Boolean expressions in the way as the C language.
Arrays - The ability to use variables with multiple elements, which could be numerically indexed.
Built-in Commands - The ability to use a few useful commands built into the shell.
Command Path Variable - The ability to define a list of paths where the shell can search for external program to execute.
Command Substitution - The ability to execute extra commands in sub shells and uses their output in the command line.
Execution Control Commands - The ability to execute commands conditionally and repeatedly.
Execution Interruption Handling - The ability to catch execution interrupts and change execution flow.
Filename Substitution - The ability to expand filename wildcard characters with real file names.
History Substitution - The ability to reuse the entire command line, or some parts, of any previously executed command.
Input and Output Redirection - The ability to change standard input and/or output from terminal console to other commands or files.
Job Control - The ability to suspend an interactive job and resume it at a later time, or send it into the "background".
Shell Scripts - The ability to execute commands stored in a script file.
Quotation and Escape Sequences - The ability to protect special characters with single quotes and backslashes.
Variable Substitution - The ability to reference values of built-in and user defined shell variables.
Working Directory Stack - The ability to remember the current and previous working directories in a stack.