remsh(1) General Commands Manual remsh(1)
NAME
remsh, rexec - execute from a remote shell
SYNOPSIS
host username] command
host username] command
host username] command
In Kerberos V5 Network Authentication Environments
host username] realm] command
host username] realm] command
DESCRIPTION
connects to a specified host and executes a specified command. The host name can be either the official name or an alias as understood by
(see gethostent(3N) and hosts(4)). copies its standard input to the remote command, the standard output of the remote command to its stan-
dard output and the standard error of the remote command to its standard error Hangup, interrupt, quit, terminate, and broken pipe signals
are propagated to the remote command. exits when the sockets associated with and of the remote command are closed. This means that nor-
mally terminates when the remote command does (see remshd(1M)).
By default, uses the following path when executing the specified command:
uses the default remote login shell with the option to execute the remote command. If the default remote shell is csh, csh sources the
remote file before the command. cannot be used to run commands that require a terminal interface (such as or commands that read their
standard error (such as In such cases, use or instead (see rlogin(1) and telnet(1)).
The remote account name used is the same as your local account name, unless you specify a different remote name with the option. This
remote account name must be equivalent to the originating account. In addition, the remote host account name must also conform to other
rules, which differ depending upon whether the remote host is operating in a Kerberos V5 Network Authentication, i.e., secure environment,
or not.
In a non-secure, or traditional environment, the remote account name must be equivalent to the originating account; no provision is made
for specifying a password with a command. For more details about hosts and how to specify them, see hosts.equiv(4). The files inspected
by on the remote host are and (see remshd(1M)).
In a Kerberos V5 Network Authentication environment, the local host must be successfully authenticated before the remote account name is
checked for proper authorization. The authorization mechanism is dependent on the command line options used to invoke on the remote host
(i.e., For more information on Kerberos authentication and authorization see the Secure Internet Services man page, sis(5) and remshd(1M).
Although Kerberos authentication and authorization may apply, the Kerberos mechanism is applied to the command or to its response. All the
information that is transferred between the local and remote host is still sent in cleartext over the network.
The default Kerberos options for the applications are set in the configuration file. Refer to the in the krb5.conf(4) manpage for more
information. The options and described in the subsequent paragraphs, can be set in the file with the tag names and respectively. Refer to
the krb5.conf(4) manpage for more information on the
The option can be set in the file within the If is set to true and the kerberos authentication fails, will use the non-secure mode of
authentication.
Note: Command line options override the configuration file options.
In a secure or Kerberos V5-based environment, the following command line options are available:
Forward the ticket granting ticket (TGT) to the remote system. The TGT
is not forwardable from that remote system.
Forward the TGT to the remote system and have it forwardable from
there to another remote system. The option and option are mutually exclusive.
Obtain tickets from the remote host in the
specified realm instead of the remote host's default realm as specified in the configuration file
Disable Kerberos authentication.
If command, is not specified, instead of executing a single command, you will be logged in on the remote host using (see rlogin(1)). Any
options typed in on the command line are transmitted to If no command and the option are specified, will be invoked with to indicate that
Kerberos authentication (or secure access) is not necessary. This means that if a password is requested, the password will be sent in
cleartext. If command is specified, options specific to are ignored by
By default, reads its standard input and sends it to the remote command because has no way to determine whether the remote command requires
input. The option redirects standard input to from This is useful when running a shell script containing a command, since otherwise remsh
may use input not intended for it. The option is also useful when running in the background from a job control shell, or Otherwise, stops
and waits for input from the terminal keyboard for the remote command. automatically redirects its input from when jobs are run in the
background.
Host names for remote hosts can also be commands (linked to in the directory If this directory is specified in the environment variable,
you can omit For example, if is the name of a remote host, is linked to and if is in your search path, the command
executes command on and the command
is equivalent to
The command works in the same way as except that it uses the library routine and for command execution (see rexec(3N) and rexecd(1M)) and
does not support Kerberos authentication. prompts for a password before executing the command instead of using for authentication. It
should be used in instances where a password to a remote account is known but there are insufficient permissions for
EXAMPLES
Shell metacharacters that are not quoted are interpreted on the local host; quoted metacharacters are interpreted on the remote host. Thus
the command line:
appends the remote file to the local file while the command line
appends to the remote file
If the remote shell is the following command line sets up the environment for the remote command before executing the remote command:
The throws away error messages generated by executing when stdin and stdout are not a terminal.
The following command line runs in the background on the local system, and the output of the remote command comes to your terminal asyn-
chronously:
The background completes when the remote command does.
The following command line causes to return immediately without waiting for the remote command to complete:
(See remshd(1M) and sh(1)). If your login shell on the remote system is csh, use the following form instead:
RETURN VALUE
If fails to set up the secondary socket connection, it returns 2. If it fails in some other way, it returns 1. If it fully succeeds in
setting up a connection with it returns 0 once the remote command has completed. Note that the return value of bears no relation to the
return value of the remote command.
DIAGNOSTICS
Besides the errors listed below, errors can also be generated by the library functions and In the case of IPv6 systems, the library func-
tions and are replaced by and respectively, and can generate errors (see rcmd(3N) and rcmd_af(3N)). These errors are preceded by the name
of the library function that generated them. can produce the following diagnostic messages:
There are two authentication mechanisms used by
One authentication mechanism is based on Kerberos and the other is not. The type of authentication mechanism is obtained
from a system file which is updated by (see inetsvcs_sec(1M)). If the system file does not contain known authentication
types, the above error is displayed.
Error in executing
is executed when the user does not specify any commands to be executed). This is followed by the error message specifying
why the execution failed.
The ``shell'' service specification is not present in the
file.
cannot establish secondary socket connection for
Error in executing system call.
Appended to this error is a message specifying the cause of the failure.
Check with the system administrator
to see if your entry in the password file has been deleted by mistake.
Kerberos-specific errors are listed in sis(5).
WARNINGS
For security reasons, the and files should exist, even if empty, and they should be readable and writable only by the owner. Note also
that all information, including any passwords asked for, is passed unencrypted between the two hosts.
If is run with an interactive command, it hangs.
DEPENDENCIES
is the same service as on BSD systems. The name was changed due to a conflict with the existing System V command (restricted shell).
AUTHOR
was developed by the University of California, Berkeley.
FILES
for version of the command invoked only with hostname
SEE ALSO
rlogin(1), remshd(1M), rexecd(1M), inetsvcs_sec(1M), gethostent(3N), rcmd(3N), rcmd_af(3N), rexec(3N), hosts(4), hosts.equiv(4),
krb5.conf(4).
remsh(1)