4.10. Restricted Shells

A restricted shell is one that disallows certain actions, such as changing directory, setting PATH, or running commands whose names contain a / character.

The original V7 Bourne shell had an undocumented restricted mode. Later versions of the Bourne shell clarified the code and documented the facility. Today, Bash and the Korn shell both supply a restricted mode, but with differing sets of items that get restricted. (See the respective manual pages for the details.)

Shell scripts can still be run, since in that case the restricted shell calls the unrestricted version of the shell to run the script. This includes the /etc/profile, $HOME/.profile, and other start-up files.

Restricted shells are not used much in practice, as they are difficult to set up correctly.