RSH(1)
NAME
rsh − restricted shell (command interpreter)
SYNOPSIS
rsh [ flags ] [ name [ arg1 ... ] ]
DESCRIPTION
Rsh is a restricted version of the standard command interpreter sh(1). It is used to set up login names and execution environments whose capabilities are more controlled than those of the standard shell. The actions of rsh are identical to those of sh, except that the following are disallowed:
cd
setting the value of $PATH
command names containing /
> and >>
When invoked with the name −rsh, rsh reads the user’s .profile (from $HOME/.profile). It acts as the standard sh while doing this, except that an interrupt causes an immediate exit, instead of causing a return to command level. The restrictions above are enforced after .profile is interpreted.
When a command to be executed is found to be a shell procedure, rsh invokes sh to execute it. Thus, it is possible to provide to the end user shell procedures that have access to the full power of the standard shell, while restricting him to a limited menu of commands; this scheme assumes that the end user does not have write and execute permissions in the same directory.
The net effect of these rules is that the writer of the .profile has complete control over user actions, by performing guaranteed setup actions, then leaving the user in an appropriate directory (probably not the login directory).
Rsh is actually just a link to sh and any flags arguments are the same as for sh(1).
The system administrator often sets up a directory of commands that can be safely invoked by rsh. Some systems also provide a restricted editor red.