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Full Discussion: while loop stops after first iteration - remote ssh exit command problem?
Top Forums Shell Programming and Scripting while loop stops after first iteration - remote ssh exit command problem? Post 302597268 by jelloir on Thursday 9th of February 2012 08:56:59 PM
Old 02-09-2012
Thanks chihung, I tried your suggestion but it still fails, so the exit doesn't appear to be the problem. If I check the return value from the ssh command it is 0, so i'm stumped? Thanks for the IFS suggestion.

The script currently looks like this:

Code:
#!/bin/bash

mxg_hosts_file="/etc/mxg/ssh-hosts"

while IFS=":" read mxg_host mxg_port ; do
    echo "Connecting and Upgrading ${mxg_host}"
    ssh root@${mxg_host} -p ${mxg_port} 'aptitude update && aptitude safe-upgrade -y && shutdown -r now'
done < ${mxg_hosts_file}

Edit - figured it out.

You have to use ssh's -n argument.

Code:
 -n      Redirects stdin from /dev/null (actually, prevents reading from
             stdin).  This must be used when ssh is run in the background.  A
             common trick is to use this to run X11 programs on a remote
             machine.  For example, ssh -n shadows.cs.hut.fi emacs & will
             start an emacs on shadows.cs.hut.fi, and the X11 connection will
             be automatically forwarded over an encrypted channel.  The ssh
             program will be put in the background.  (This does not work if
             ssh needs to ask for a password or passphrase; see also the -f
             option.)

Last edited by jelloir; 02-09-2012 at 10:03 PM..
 

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LEARN ABOUT SUSE

ssh-keysign

SSH-KEYSIGN(8)						    BSD System Manager's Manual 					    SSH-KEYSIGN(8)

NAME

     ssh-keysign -- ssh helper program for host-based authentication

SYNOPSIS

     ssh-keysign

DESCRIPTION

     ssh-keysign is used by ssh(1) to access the local host keys and generate the digital signature required during host-based authentication with
     SSH protocol version 2.

     ssh-keysign is disabled by default and can only be enabled in the global client configuration file /etc/ssh/ssh_config by setting
     EnableSSHKeysign to ``yes''.

     ssh-keysign is not intended to be invoked by the user, but from ssh(1).  See ssh(1) and sshd(8) for more information about host-based authen-
     tication.

FILES

     /etc/ssh/ssh_config
	     Controls whether ssh-keysign is enabled.

     /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
	     These files contain the private parts of the host keys used to generate the digital signature.  They should be owned by root, read-
	     able only by root, and not accessible to others.  Since they are readable only by root, ssh-keysign must be set-uid root if host-
	     based authentication is used.

SEE ALSO

     ssh(1), ssh-keygen(1), ssh_config(5), sshd(8)

HISTORY

     ssh-keysign first appeared in OpenBSD 3.2.

AUTHORS

     Markus Friedl <markus@openbsd.org>

BSD
								   May 31, 2007 							       BSD
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