ssh's command mode

bits · 08-13-2009, 06:21 PM

Hi,

I want to use ssh to execute a command and to wait endlessly to log everything (in file) that comes as a stream of the connected server.

But unfortunately, in the manual its written "If command is specified, it is executed on the remote host instead of a login shell"

So what happens is that when I specify my command:

ssh user@server "my_command"

It executed the command and the flow of execution returns to bash shell. So basically my session ends right after the command is executed. This happens only in case I specify command in the command line. If I login into ssh manually and then type "my_command", then the session doesn't end.

I want the ssh not to exit, because after "my_command" executes, I want to capture everything in the session.

Does anyone know a way out of this problem?

thanks,

fordeck · 08-13-2009, 06:36 PM

Have you tried redirecting the output to a file? An example would be:

Code:

ssh user@server "my_command" > filename

This would send the output to "filename" on your local machine.

Let us know if this is what you are looking for?

Regards

Fordeck

onebuck · 08-13-2009, 06:37 PM

Hi,

Welcome to LQ!

Quote:

Originally Posted by bits

Hi,

I want to use ssh to execute a command and to wait endlessly to log everything (in file) that comes as a stream of the connected server.

But unfortunately, in the manual its written "If command is specified, it is executed on the remote host instead of a login shell"

So what happens is that when I specify my command:

ssh user@server "my_command"

It executed the command and the flow of execution returns to bash shell. So basically my session ends right after the command is executed. This happens only in case I specify command in the command line. If I login into ssh manually and then type "my_command", then the session doesn't end.

I want the ssh not to exit, because after "my_command" executes, I want to capture everything in the session.

Does anyone know a way out of this problem?

thanks,

I'm not sure about what you are wanting to do? You state that if you login via ssh manually and submit your command on cli every thing is joy. Why not just capture at the time of the current session?

Your example states to 'ssh user@server "my_command", so everything is going as you have instructed.

Quote:

excerpt 'man ssh';

DESCRIPTION
ssh (SSH client) is a program for logging into a remote machine and for
executing commands on a remote machine. It is intended to replace rlogin
and rsh, and provide secure encrypted communications between two
untrusted hosts over an insecure network. X11 connections and arbitrary
TCP ports can also be forwarded over the secure channel.

ssh connects and logs into the specified hostname (with optional user
name). The user must prove his/her identity to the remote machine using
one of several methods depending on the protocol version used (see
below).

kilgoretrout · 08-13-2009, 06:38 PM

Did you try:

ssh user@server "my_command &"

The ampersand at the end should background the task and return you to a bash prompt on the remote machine while it runs. At least that's my hope; have never done this myself over ssh but the theory seems sound. See this article on backgrounding with &:

http://lowfatlinux.com/linux-processes.html