C shell

tcsh and sh side-by-side on a Mac OS X desktop
C Shell running on Windows Services for UNIX
64-bit Hamilton C shell on a Windows 7 desktop.

Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s.

- C shell

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Command-line interface

A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text.

Screenshot of a sample Bash session in GNOME Terminal 3, Fedora 15
Screenshot of Windows PowerShell 1.0, running on Windows Vista
A graphical user interface with icons and windows (GEM 1.1 Desktop)
Apple Computer's CommandShell in A/UX 3.0.1
GNU Octave's GUI with command-line interface
Bourne shell interaction on Version 7 Unix
Prompt of a BBC Micro after switch-on or hard reset
An MS-DOS command line, illustrating parsing into command and arguments
The end of the HELP command output from RT-11SJ displayed on a VT100
A Teletype Model 33 ASR teleprinter keyboard with punched tape reader and punch
DEC VT52 terminal

Examples of command-line interpreters include DEC's DIGITAL Command Language (DCL) in OpenVMS and RSX-11, the various Unix shells (sh, ksh, csh, tcsh, zsh, Bash, etc.), CP/M's CCP, DOS' COMMAND.COM, as well as the OS/2 and the Windows CMD.EXE programs, the latter groups being based heavily on DEC's RSX-11 and RSTS CLIs.

Unix shell

Command-line interpreter or shell that provides a command line user interface for Unix-like operating systems.

tcsh and sh shell windows on a Mac OS X Leopard desktop

But the most widely distributed and influential of the early Unix shells were the Bourne shell and the C shell.

Shell script

Computer program designed to be run by the Unix shell, a command-line interpreter.

Editing a FreeBSD shell script for configuring ipfirewall

The C shell

Bill Joy

American computer engineer and venture capitalist.

Joy at World Economic Forum (Davos), 2003-01

Some of his most notable contributions were the ex and vi editors and the C shell.

Berkeley Software Distribution

Discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley.

Simplified evolution of Unix systems. Not shown are Junos, PlayStation 3 system software and other proprietary forks.
The VAX-11/780, a typical minicomputer used for early BSD timesharing systems
"4.3 BSD UNIX" from the University of Wisconsin circa 1987. System startup and login.
4.3 BSD from the University of Wisconsin. Displaying the man page for Franz Lisp
Tape for SunOS 4.1.1, a 4.3BSD derivative
Sony NEWS workstation running the BSD-based NEWS-OS operating system

The second Berkeley Software Distribution (2BSD), released in May 1979, included updated versions of the 1BSD software as well as two new programs by Joy that persist on Unix systems to this day: the vi text editor (a visual version of ex) and the C shell.

Pipeline (Unix)

Mechanism for inter-process communication using message passing.

A pipeline of three program processes run on a text terminal

In the csh shell, for instance, using instead of signifies that the standard error stream should also be merged with the standard output and fed to the next process.

Bash (Unix shell)

Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell.

Screenshot of a Bash session
Screenshot of a Bash session

Other features, e.g., history, are copied from csh and ksh.


Screenshot of a sample tcsh session

tcsh ( “tee-see-shell”, “tee-shell”, or as “tee see ess aitch”, ) is a Unix shell based on and backward compatible with the C shell.

C (programming language)

General-purpose computer programming language.

Dennis Ritchie (right), the inventor of the C programming language, with Ken Thompson
The cover of the book The C Programming Language, first edition, by Brian Kernighan and Dennis Ritchie
"Hello, World!" program by Brian Kernighan (1978)
The C Programming Language
The TIOBE index graph, showing a comparison of the popularity of various programming languages

Many later languages have borrowed directly or indirectly from C, including C++, C#, Unix's C shell, D, Go, Java, JavaScript (including transpilers), Julia, Limbo, LPC, Objective-C, Perl, PHP, Python, Ruby, Rust, Swift, Verilog and SystemVerilog (hardware description languages).

Bourne shell

Shell command-line interpreter for computer operating systems.

Bourne shell interaction on Version 7 Unix
Version 7 Unix: the original Bourne shell manual page. PDP-11 simulation with SIMH
Interaction with pdksh in OpenBSD (default shell)

The Korn shell (ksh) written by David Korn based on the original Bourne Shell source code, was a middle road between the Bourne shell and the C shell.