rsh, remsh, remote_shell - remote shell
rsh [-n] [-l username] hostname command
rsh hostname [-n] [-l username] command
remsh [-n] [-l username] hostname command
remsh hostname [-n] [-l username] command
hostname [-n] [-l username] command
rsh connects to the specified hostname and executes the
specified command. rsh copies its standard input to the
remote command, the standard output of the remote command to
its standard output, and the standard error of the remote
command to its standard error. Interrupt, quit, and ter-
minate signals are propagated to the remote command. rsh
normally terminates when the remote command does.
If you omit command, instead of executing a single command,
rsh logs you in on the remote host using rlogin(1).
rsh will not return the exit status code of command.
Shell metacharacters which are not quoted are interpreted on
the local machine, while quoted metacharacters are inter-
preted on the remote machine. See EXAMPLES.
If there is no locale setting in the initialization file of
the login shell (.cshrc, . . .) for a particular user, rsh
always executes the command in the "C" locale instead of
using the default locale of the remote machine.
The following options are supported:
Uses username as the remote username instead of your
local username. In the absence of this option, the
remote username is the same as your local username.
-n Redirects the input of rsh to /dev/null. You sometimes
need this option to avoid unfortunate interactions
between rsh and the shell which invokes it. For exam-
ple, if you are running rsh and invoke a rsh in the
background without redirecting its input away from the
terminal, it will block even if no reads are posted by
the remote command. The -n option will prevent this.
The type of remote shell (sh, rsh, or other) is determined
by the user's entry in the file /etc/passwd on the remote
The following operand is supported:
The command to be executed on the specified hostname.
See largefile(5) for the description of the behavior of rsh
and remsh when encountering files greater than or equal to 2
Gbyte ( 2**31 bytes).
The rsh and remsh commands are IPv6-enabled. See ip6(7P).
Hostnames are given in the hosts database, which may be con-
tained in the /etc/hosts file, the Internet domain name
database, or both. Each host has one official name (the
first name in the database entry) and optionally one or more
nicknames. Official hostnames or nicknames may be given as
If the name of the file from which rsh is executed is any-
thing other than rsh, rsh takes this name as its hostname
argument. This allows you to create a symbolic link to rsh
in the name of a host which, when executed, will invoke a
remote shell on that host. By creating a directory and popu-
lating it with symbolic links in the names of commonly used
hosts, then including the directory in your shell's search
path, you can run rsh by typing hostname to your shell.
If rsh is invoked with the basename remsh, rsh will check
for the existence of the file /usr/bin/remsh. If this file
exists, rsh will behave as if remsh is an alias for rsh. If
/usr/bin/remsh does not exist, rsh will behave as if remsh
is a host name.
Each remote machine may have a file named /etc/hosts.equiv
containing a list of trusted hostnames with which it shares
usernames. Users with the same username on both the local
and remote machine may run rsh from the machines listed in
the remote machine's /etc/hosts file. Individual users may
set up a similar private equivalence list with the file
.rhosts in their home directories. Each line in this file
contains two names: a hostname and a username separated by a
space. The entry permits the user named username who is
logged into hostname to use rsh to access the remote machine
as the remote user. If the name of the local host is not
found in the /etc/hosts.equiv file on the remote machine,
and the local username and hostname are not found in the
remote user's .rhosts file, then the access is denied. The
hostnames listed in the /etc/hosts.equiv and .rhosts files
must be the official hostnames listed in the hosts database;
nicknames may not be used in either of these files.
You cannot log in using rsh as a trusted user from a trusted
hostname if the trusted user account is locked.
rsh will not prompt for a password if access is denied on
the remote machine unless the command argument is omitted.
Example 1: Using rsh to append files
The following command:
example% rsh lizard cat lizard.file >> example.file
appends the remote file lizard.file from the machine called
lizard to the file called example.file on the machine called
example, while the command:
example% rsh lizard cat lizard.file ">>" lizard.file2
appends the file lizard.file on the machine called lizard to
the file lizard.file2 which also resides on the machine
The following exit values are returned:
0 Successful completion.
1 An error occurred.
Internet host table
trusted remote hosts and users
system password file
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWrcmdc |
| CSI | enabled |
on(1), rlogin(1), telnet(1), vi(1), in.named(1M), hosts(4),
hosts.equiv(4), ipnodes(4), attributes(5), largefile(5),
When a system is listed in hosts.equiv, its security must be
as good as local security. One insecure system listed in
hosts.equiv can compromise the security of the entire sys-
You cannot run an interactive command (such as vi(1)). Use
rlogin if you wish to do this.
Stop signals stop the local rsh process only. This is argu-
ably wrong, but currently hard to fix for reasons too com-
plicated to explain here.
The current local environment is not passed to the remote
Sometimes the -n option is needed for reasons that are less
than obvious. For example, the command:
example% rsh somehost dd if=/dev/nrmt0 bs=20b | tar xvpBf -
will put your shell into a strange state. Evidently, what
happens is that the tar terminates before the rsh. The rsh
then tries to write into the ``broken pipe'' and, instead of
terminating neatly, proceeds to compete with your shell for
its standard input. Invoking rsh with the -n option avoids
This bug occurs only when rsh is at the beginning of a pipe-
line and is not reading standard input. Do not use the -n
if rsh actually needs to read standard input. For example:
example% tar cf - . | rsh sundial dd of=/dev/rmt0 obs=20b
does not produce the bug. If you were to use the -n in a
case like this, rsh would incorrectly read from /dev/null
instead of from the pipe.
Man(1) output converted with