The Free On-line Dictionary of Computing (19 January 2023):

rsh

   Remote shell.

   A Berkeley Unix networking command to execute a given
   command on a remote host, passing it input and receiving its
   output.  Rsh communicates with a daemon on the remote host.
   It is sometimes called remsh to avoid confusion with the
   restricted shell, also called "rsh".

   Unix manual page: rsh(1).

   (1994-12-08)