SSH onto nodes in a loop and then get off

MOFH · 11-20-2009, 10:03 AM

Ok I know this question has been asked before as I've read through the threads and I've also done this before but can't get it to work now

Simple question really:
log onto a list of nodes say node 2-5 see who's on and then leave
I have something like:
for u 2 3 4 5 ; do
ssh -n node$u (also tried rsh -n and just rsh and ssh)
echo $u
who
logout (or exit)
done

The problem is it logs onto the nodes but doesn't logoff. Is there something fundamentally wrong with this bash script?

Thanks
Mo

TB0ne · 11-20-2009, 10:27 AM

Quote:

Originally Posted by MOFH

Ok I know this question has been asked before as I've read through the threads and I've also done this before but can't get it to work now

Simple question really:
log onto a list of nodes say node 2-5 see who's on and then leave
I have something like:
for u 2 3 4 5 ; do
ssh -n node$u (also tried rsh -n and just rsh and ssh)
echo $u
who
logout (or exit)
done

The problem is it logs onto the nodes but doesn't logoff. Is there something fundamentally wrong with this bash script?

Thanks
Mo

My guess would be that you're starting a new shell on the remote box, while the commands are in the shell-script on the local box. You initiate the new shell fine, but then it sits there.

Try putting the command on the SSH line, like:

Code:

ssh -n node$u "insert command name here"

That'll just attach and run that command, without opening a new shell on the remote end. You might also want to look at the "fanout" program (Google can show you the way...), or write a script using "expect", so it'll enter the commands as if you were typing them.

MOFH · 11-20-2009, 10:41 AM

Quote:

Originally Posted by TB0ne

My guess would be that you're starting a new shell on the remote box, while the commands are in the shell-script on the local box. You initiate the new shell fine, but then it sits there.

Try putting the command on the SSH line, like:

Code:

ssh -n node$u "insert command name here"

That'll just attach and run that command, without opening a new shell on the remote end. You might also want to look at the "fanout" program (Google can show you the way...), or write a script using "expect", so it'll enter the commands as if you were typing them.

Thanks!
I tried that and it seems to work though it gives a silly warning regarding "use exit instead of logout" (which is bad idea). I'll give the other things a go because I want it to take commands from my script instead of std input.

Mo