xrsh - start an X program on a remote machine
] [ -version
] [ -l username
] [ -screen screen-#
] [ -debug
] [ -debug2
[ arguments ... ] ]
runs the given X command on a remote host. It sets up the
environment for that command such that it will display its windows on the
current server's screen by propagating the $DISPLAY environment variable. If
not specified, the default client is xterm
. Xrsh automatically selects
(1) or rcmd
(1) to execute remote commands,
depending on what is available the O/S environment.
Xrsh automatically handles authentication so that the remote client will be
allowed to open windows on the server. It does this in several different ways
depending on the value of the $XRSH_AUTH_TYPE environment variable or the
By default, xrsh will use xhost to enable the remote client to open a server
connection. It can also be told to use xauth to merge local keys into a remote
authorization file. Or it can pass the $XAUTHORITY environment variable to the
remote host in order to share a common NFS mounted authority file. It can also
be directed to do nothing in the case where no explicit authorization is
Users who just want a remote terminal window might look at xrsh's sister
command, xrlogin(1). Xrlogin uses a locally running xterm to open an rlogin
connection to a remote host. The decision on whether to use "xrsh host
xterm" or "xrlogin host" should be based on several factors. If
X is unavailable on the remote host or the local terminal emulator has better
features, use xrlogin. In general, the author recommends using xrsh over
xrlogin in most situations.
If the command to execute on the remote host is an xterm, xrsh automatically
passes the -name argument to xterm with a value of "xterm-hostname"
where hostname is the name of the remote host. This allows the user to specify
resources in their server's resource manager which are specific to xterms from
a given host. For example, this feature can be used to make all xterm windows
from a given remote host be the same color or use a specific font or start up
in a specific place on the screen. Xrlogin passes the same string so they are
compatible in this regard. This feature can be overridden by specifying your
own -name argument on the xterm command line.
If the command to execute on the remote host is an xterm, xrsh specifies that
the default title for the new xterm will be "xterm@hostname" where
hostname is the name of the remote host. This can also be overridden by
specifying your own -title argument on the xterm command line.
Xrsh is very careful not to leave any extra processes on either the local or
remote machine waiting around for the client to exit. In some remote
environments (particularly some Sys V implementations of csh and rsh), this is
impossible and xrsh should be run as a background command.
Note that xrsh options precede the given X command and its arguments.
- -auth authtype
- Choose what type of X authorization (or access control) is going to be
used. Authtype can be one of "xhost", "xauth",
"xhost-xterminal", "environment", or "none".
The default is xhost, but the default can be set by setting the value of
the environment variable $XRSH_AUTH_TYPE.
- If xhost is specified and the X server is running on the local machine,
xhost will be run locally to enable the remote host to open an X
connection. If the server is on a third host (not the one where xrsh is
running and not the one where you wish to run the command), rsh will be
used to run xhost on the server host to authorize the host where the
command will be run.
- If xauth is specified, then xrsh will merge the entries for the server
from the local $XAUTHORITY file into that of the remote host using
- The authtype xhost-xterminal is intended for use by people using X
terminals. If xhost-xterminal is used, then the first time xrsh is run, it
runs xhost locally to enable the remote host for access. This should work
since (theoretically) the first time it is run is on the XDMCP host for
the X terminal. From then on it propagates the name of that host to all
remote hosts via the environment variable $XHOST. In subsequent
invocations from remote hosts, xrsh uses rsh to connect to the host $XHOST
and run xhost to enable new remote hosts.
- Authtype "none" does no explicit work for access control. Use
this if you don't enable access control or if you use another mechanism
for access control.
- Finally, authtype "environment" automatically propagates the
environment variable $XAUTHORITY to remote hosts, assuming that it is an
NFS mounted location that can be accessed from all hosts.
- Normally xrsh redirects standard input and standard output to /dev/null in
an effort to cause unneeded rshd and shell processes to exit. As a result,
the user can't usually see any errors that might occur (like a
"Permission denied." from rsh). If you are having trouble
getting xrsh to work with a remote host, try giving the -debug switch to
see if any errors are being generated.
- This switch causes xrsh to turn on the -x option in the shell so that the
user can see every shell command executed by xrsh. Only use this script if
you are debugging the xrsh code itself.
- Print out the argument list to standard output.
- -l username
- Use the -l switch to specify a different user name to use for logging in
via rsh on the remote host.
- -pass envlist
- Envlist is a quote delimited string naming an arbitrary set of environment
variables to pass on to the shell environment on the remote host. If one
wanted to set $XRSH_AUTH_TYPE and $XAUTHORITY to the remote host, one
could use: -pass "XRSH_AUTH_TYPE XAUTHORITY". A default set of
environment variables to pass may be set using the environment variable
- -screen screen-#
- Specify a different screen on the server on which to display the remote
- Print out version information and exit.
The environment variables XRSH_AUTH_TYPE and XRSH_ENVS_TO_PASS which can be used
to set switch defaults are overridden if the equivalent switch is specified as
- The $XAUTHORITY environment variable is passed to the remote host if the
authtype specified by -auth or $XRSH_AUTH_TYPE is
- This environment variable can be used to specify the default type of
authorization or access control. The values it can be set to are the same
as the values for the argument -auth.
- If the environment variable XRSH_RSH_ERRORS is set to the name of a file,
any rsh errors will appear in that file on the remote host. If that
variable is unset, error messages will be thrown away unless the -debug
switch is given. (Note: don't use ~ in the filename because it will expand
to ~ on the local host, but try to put the errors in that file on the
Make sure your PATH environment variable on the remote host is set in your
.cshrc or .bashrc so that rsh programs have access to it. (/bin/sh and
/bin/ksh users have a hard time time here since their shells don't execute any
init files under rsh. You can use the XRSH_ENVS_TO_PASS environment variable
to pass the PATH environment variable to the remote host. Optionally, you can
type a full path to xrsh in that case. (E.g. xrsh remote-host
Make sure your PATH environment variable on the remote host includes the
directory containing the X programs. This is often /usr/bin/X11 or
Make sure you have rsh configured to work on the remote host. You can test this
by typing: rsh remote-host echo '$PATH' This will prove that rsh works and
show you the PATH that will be used on the remote host. If you get
"Permission denied." you probably need to update your ~/.rhosts file
on the remote host. See rlogin(1).
- xrsh yoda
- Start an xterm on the host yoda which displays on the current X server.
Use xhost for access control.
- xrsh -auth xauth underdog emacs
- Start an emacs on the host underdog. Merge xauth authorization entries for
this server into the authority file on the remote host.
- xrsh -l mjd -auth none -pass XRSH_AUTH_TYPE -debug tigger xterm -fn
- Start an xterm on the host tigger in a very small font, propagate the
environment variable $XRSH_AUTH_TYPE to the remote host, login to the
remote host using the id "mjd", don't do any specific
authorization and don't redirect standard/error output to /dev/null so I
can see any errors.
If the values of the environment variables specified in -pass or
$XRSH_ENVS_TO_PASS contain quote characters, xrsh will have difficulty.
If the remote host can't resolve the hostname of the server host (through
/etc/hosts, DNS or NIS), the remote client will not be able to open a
connection to the server.
System V users may need to make the first line of the script begin with colon
If you think you have found a bug, the first thing you should do is to check on
ftp.x.org in the contrib directory using anonymous FTP to see if there is a
new version of xrsh there that already fixes the bug. If not, send email to
"email@example.com" and be sure to have the token xrsh somewhere in the
Subject: line. Be sure to report the operating system type and version at both
ends of the xrsh connection and a description of the command you are using and
what authentication mode you are using.
xrlogin(1), rsh(1), xhost(1), xauth(1)
James J. Dempsey <firstname.lastname@example.org> with help and suggestions from many people
including email@example.com, firstname.lastname@example.org, email@example.com and
firstname.lastname@example.org, <email@example.com>, and