Handling a "No route to host" message in a script

kaujot · 03-27-2008, 03:18 AM

Okay,

So the script I'm trying to write looks at every connected computer in our lab, and prints out the ones who have no users. However, if a machine responds with "No route to host," I don't want that message nor the name of the machine to the printed.

Here's my script so far:

Code:

#!/bin/bash

machines=$(cshosts publinux)
for mach in $machines; do
    if [ "$($mach who)" == "" ]; then
      if [ "$($mach who)" != "$mach.url: No route to host" ]; then
        echo $mach
      fi
    fi
done

My output:
(Machine)
(Machine)
(Machine.url: No route to host)
(Machine.url: No route to host)
(Machine) [same as machine with no route found]

What's wrong with my logic? I can't quite seem to figure this out.

Thanks for your help.

unSpawn · 03-27-2008, 05:56 AM

The easiest way (if possible) would be to avoid string ops, set a flag like error=0; do
output=$(thecommand --options $item 2>&1); and use the exit value, like error=$?.
[ $error -ge 0 ] && { echo you have a problem with this host; so you can skip the rest; }
If you need to use the output then you could echo "$output"|grep -q 'No.route' && error=1
or case "$output" in *route*) error=1;; esac to set a flag. So based on [ $error -eq 0 ] you
know if you want to && echo "$machine $output".

Code:

#!/bin/bash
LIST=$(cshosts publinux); for ITEM in $LIST; do
 ERROR=0; OUTPUT=$($CMD --options $ITEM 2>&1)
 ERROR=$?; [ $ERROR -eq 0 ] && echo "${ITEM}: \
${OUTPUT}"; done; exit 0

kaujot · 03-27-2008, 06:14 PM

Thank you! Worked wonderfully.