File: inetutils.info,  Node: rsh invocation,  Next: talk invocation,  Prev: rlogin invocation,  Up: Top

15 'rsh': Remote shell
**********************

'rsh' executes commands on a remote host and copies its local standard
input to that of the remote command, as well as the remote standard
output to the local standard output, and the remote standard error to
the local standard error.  Locally raised interrupt, quit and terminate
signals are all propagated to the remote command.  Normally 'rsh'
terminates when the remote command does so.

   When using the 'rsh' command, you can for convenience create a link
in your path, using a host name as name of the link.  For example:

     # ln -s /usr/bin/rsh HOSTNAME
     # HOSTNAME ls

Afterwards, HOSTNAME will be passed to 'rsh' as host name whenever the
command HOSTNAME is issued.

   'rsh' allows access to the remote host without the use of a password.
The prerequisite is a suitable specification in '~/.rhosts'.  For
details, *Note rcmd: (libc)rcmd.

   If no command is specified for 'rsh' ar argument following the host
name, then you will be logged in on the remote host using 'rlogin'.

15.1 Command line options
=========================

The options are as follows :

'-4'
'--ipv4'
     Use only IPv4.

'-6'
'--ipv6'
     Use only IPv6.

'-d'
'--debug'
     Turns on socket debugging used for communication with the remote
     host.

'-l USER'
'--user=USER'
     By default, the remote username is the same as the local username.
     The '-l' option and the 'username@host' format allow the remote
     user name to be specified.  Kerberos authentication is used,
     whenever available, and authorization is determined as in 'rlogin'
     (*note rlogin invocation::).

'-n'
'--no-input'
     Use '/dev/null' for all input, telling the server side that we send
     no material.  This can prevent the remote process from blocking,
     should it optionally accept more input.  The option is void
     together with encryption.

The next three options are available only if the program has been
compiled with support for Kerberos authentication.

'-k REALM'
'--realm=REALM'
     The option requests rsh to obtain tickets for the remote host in
     realm REALM instead of the remote host's realm.

'-K'
'--kerberos'
     Turns off all Kerberos authentication.

'-x'
'--encrypt'
     Turns on encryption for all data passed via the rsh session.  This
     may impact response time and CPU utilization, but provides
     increased security.

Finally, some compatibility options are present:

'-8'
'--8-bit'
'-e CHAR'
'--escape=CHAR'
'-E'
'--no-escape'
     Ignored during normal operation, but passed on to 'rlogin' when
     'rsh' is invoked without a command argument.

15.2 Note on stream redirections
================================

Beware that non-quoted shell metacharacters are interpreted on the local
machine, while quoted metacharacters are interpreted on the remote
machine.  For example:

     rsh otherhost  cat remotefile >> localfile
     rsh otherhost  cat remotefile ">>" otherfile

The first command appends the contents of 'remotefile', as found on the
remote host, to the file 'localfile' on the local host, since the local
shell will intercept the redirection and will thus receive whatever the
remote process directs to stdout.

   In contrast, the second command will append the contents of the same
file 'remotefile' to a file named 'otherfile' again, but this time the
file is located on the remote host.  The effect of quoting the
redirection operator is to execute the command

     cat remotefile >> localfile

entirely on the remote most, whence stdout at the remote host will have
nothing to transmit to the listening local host!.