The standard shell allows a user to open files, execute commands, and so on. The restricted shell is invoked with the /usr/lib/rsh command. The restricted shell can be used to limit the ability of a user to change directories and to execute commands. Note that the restricted shell is not the remote shell, which is /usr/sbin/rsh. The restricted shell differs from the standard shell in the following ways:
The user is limited to the user's home directory, so the user cannot use the cd command to change directories. Therefore, the user cannot browse system files.
The user cannot change the PATH variable, so the user can use only commands in the PATH set by the system administrator. The user also cannot execute commands or scripts by using a complete path name.
The user cannot redirect output with > or >>.
The restricted shell enables you to limit a user's ability to stray into the system files. The shell creates a limited environment for a user who needs to perform specific tasks. The restricted shell is not completely secure, however, and is only intended to keep unskilled users from inadvertently doing damage.
For information about the restricted shell, see the rsh(1M) man page.
A more secure alternative to the restricted shell is the Secure Shell, the ssh command. The Secure Shell enables users to securely access a remote host over an unsecured network. For information about using the Secure Shell, see Chapter 6, Secure Shell Administration (Reference).