.CSH File Extension

In the late 1970s, developer Bill Joy created csh. This Unix shell, which is included in many Unix distributions and also available in macOS, allows users to write and execute commands structured similarly to C statements.

Users who want to quickly execute multiple C shell commands in succession can save those commands as a C shell script. These scripts are plain text files, saved with the .csh extension, that users can create and edit in any text editor. Users can then call their CSH file with the C shell to execute the script it contains.

On rare occasions, C shell scripts may instead be saved with the .SH extension. One way to recognize a C shell script is to look for the string #!/bin/csh in the script's first line. Most C shell scripts include this string, which tells the shell the script should be executed using the C shell interpreter.