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.\"	from: @(#)rsh.1	6.10 (Berkeley) 7/24/91
.\"
.Dd July 24, 1991
.Dt RSH 1
.Os
.Sh NAME
.Nm rsh
.Nd remote shell
.Sh SYNOPSIS
.Nm rsh
.Op Fl Kdnx
.Op Fl k Ar realm
.Op Fl l Ar username
.Ar hostname
.Op Ar command
.Sh DESCRIPTION
.Nm
executes
.Ar command
on
.Ar hostname .
.Pp
.Em Note:
.Nm
has been deprecated in favor of
.Xr ssh 1 .
Use of
.Nm
is discouraged due to the inherent insecurity of host-based authentication.
.Pp
.Nm
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 terminate signals are propagated to the remote
command;
.Nm
normally terminates when the remote command does.
.Pp
.Nm
first attempts to use the Kerberos authorization mechanism, described below.
If the remote host does not support Kerberos the standard Berkeley
.Pa rhosts
authorization mechanism is used.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl K
Disable all Kerberos authentication.
.It Fl d
Enable socket debugging (using
.Xr setsockopt 2 )
on the
.Tn TCP
sockets used for communication with the remote host.
.It Fl k
Causes
.Nm
to obtain tickets for the remote host in
.Ar realm
instead of the remote host's realm as determined by
.Xr krb_realmofhost 3 .
.It Fl l
By default, the remote username is the same as the local username.
The
.Fl l
option allows the remote name to be specified.
.It Fl n
Redirect input from the special device
.Pa /dev/null
(see the
.Sx BUGS
section of this manual page).
.El
.Pp
If no
.Ar command
is specified, you will be logged in on the remote host using
.Nm rlogin
if it exists on the system or
.Xr telnet 1
if not.
.Pp
If
.Nm
is not invoked with the standard program name
.Pq Dq rsh ,
it uses this name as its
.Ar hostname
argument.
.Pp
Shell meta-characters which are not quoted are interpreted on local machine,
while quoted meta-characters are interpreted on the remote machine.
For example, the command
.Pp
.Dl $ rsh otherhost cat remotefile >> localfile
.Pp
appends the remote file
.Ar remotefile
to the local file
.Ar localfile ,
while
.Pp
.Dl $ rsh otherhost cat remotefile \&">>\&" other_remotefile
.Pp
appends
.Ar remotefile
to
.Ar other_remotefile .
.\" .Pp
.\" Many sites specify a large number of host names as commands in the
.\" directory /usr/hosts.
.\" If this directory is included in your search path, you can use the
.\" shorthand ``host command'' for the longer form ``rsh host command''.
.Sh KERBEROS AUTHENTICATION
If Kerberos is configured on the system, each user may have a private
authorization list in the file
.Pa .klogin
in their home directory.
Each line in this file should contain a Kerberos principal name of the form
.Ar principal.instance@realm .
If the originating user is authenticated to one of the principals named in
.Pa .klogin ,
access is granted to the account.
The principal
.Ar accountname.@localrealm
is granted access if there is no
.Pa .klogin
file.
Otherwise a login and password will be prompted for on the remote machine
as in
.Xr login 1 .
To avoid certain security problems, the
.Pa .klogin
file must be owned by the remote user.
.Sh FILES
.Bl -tag -width /etc/hosts -compact
.It Pa /etc/hosts
.El
.Sh SEE ALSO
.Xr telnet 1 ,
.Xr kerberos 3 ,
.Xr krb_realmofhost 3 ,
.Xr krb_sendauth 3 ,
.Xr rcmd 3
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .
.Sh BUGS
If you are using
.Xr csh 1
and put a
.Nm
in the background without redirecting its input away from the terminal,
it will block even if no reads are posted by the remote command.
If no input is desired you should redirect the input of
.Nm
to
.Pa /dev/null
using the
.Fl n
option.
.Pp
You cannot run an interactive command
(like
.Xr rogue 6
or
.Xr vi 1 )
using
.Nm rsh ;
use
.Xr telnet 1
instead.
.Pp
Stop signals stop the local
.Nm
process only; this is arguably wrong, but currently hard to fix for reasons
too complicated to explain here.
.Pp
.Nm
does not currently support encryption of the datastream when Kerberos
authentication is used.