rudimentary ssh cmd wrapper with 1 small (and hopefully obvious) bug

[Dreico-Hyper-Dynamics]

Greetings python folks !

In a fit of curiosity to code some Python for the 1st time ever, as
a little project I made a rudimentary ssh command wrapper called
brussh, the idea of which is to send commands
to several machines at the same time (so far using a shell script loop
and working on "1 target at a a time"), & working ideally in situations
where ssh is configged to not need a passwd, using RSA/DSA keys
or whatever you like.

$ host001 > brush
USAGE:
You need to enter a hostname followed by some commands, like this:
brush <hostame> <commands> <commands> ...

It works fine except in situations where there is no output
from the ssh command that it's throwing at the target i.e.

$ host001 > brush host002 'ps -ef | grep ZZZZZZZZ'
===== HOST002 OUTPUT ===============================>
Traceback (innermost last):
  File "/home/a/ad/scripts/brush", line 84, in ?
    print "=====", node_in_caps, "OUTPUT
===============================>\n", the_command()
  File "/home/a/ad/scripts/brush", line 65, in the_command
    return command_results
NameError: command_results          <<< ugly crash :(

Otherwise it does what you expect:

$ host001 > brush host002 'ps -ef | grep syslog'
===== HOST002 OUTPUT ===============================>
root       538     1  0 Feb25 ?        00:22:04 syslogd -m 0
 root     14624     1  0 Feb28 ?        00:00:05 /usr/sbin/notd -l syslog --
/usr
$ host001 >

---

Where this gets lost (and I'm not sure I fully understand what's going on in
this bit of code) is here:
############################################################################
#
### Function "the_command"

def the_command():
        payload = string.join(sys.argv[1:])
        sshcmd = 'ssh -1 -o StrictHostKeyChecking=no -l root ' + payload
        output = os.popen('{ ' + sshcmd + '; } 2>&1', 'r')

        while 1:
          line = output.readlines()
          if not line: break                            <<<<<<<    is this
the right way to handle a
          else:                                                <<<<<<<
possible 'null string output" situation ?
                command_response = string.join(line[:])
        return command_response

############################################################################
#
#
# MAIN PROGRAM
#
############################################################################
#

import string, os, sys
argnum = len(sys.argv)
if argnum < 3: Usage()
else:
    machine = sys.argv[1]
    node_in_caps = string.upper(machine)
    listening_status = is_it_listening()
    if listening_status == 1:
        print "=====", node_in_caps, "OUTPUT
===============================>\n", the_command()      <<<
  else:
        print "X ===", node_in_caps, "IS NOT CONTACTABLE ==================
X\n"
        sys.exit(1)

I realise it's just a simple wrapper written by a beginner at this stage,
but
even so, can anyone give me any pointers as to what the obvious mistake
is ? (hopefully obvious to you in this case =)))

Thanks for you comments,

Andrei