The restricted shell

A restricted shell prevents a user from gaining full access to a system. For example, you can use a restricted shell to give a co-worker limited access to your computer to share tools that are located in a particular directory.

You can run the Korn shell as a restricted shell by invoking it with the name ksh -r. In a restricted shell, the following conditions apply:

• The cd(1) command is disabled.
• The SHELL, ENV, and PATH environment variables cannot be changed.
• You cannot use absolute or relative paths in command names.
• You cannot use the -p option of the command(1) built-in command.
• File redirections that create files, such as >, >>, and >|, cannot be used.

By default, no restricted shell binary named rsh is installed. The rsh name for the restricted shell conflicts with the rsh remote-shell utility. Instead of typing rsh to run the restricted shell, type ksh(1) with the -r option; that is, ksh -r.