nagios plugin to compare (master/slave) SOA records

This is a Nagios script to compare the master ns and the slave ns SOA records.
So you can know if the slave zone is expired, or is not in sync with the master.

http://exchange.nagios.org/directory/Plugins/Network-Protocols/DNS/checkexpire/details

https://github.com/alcir/checkexpire.sh

bash while loop, function and ssh

Yesterday I struggled an entire morning with a while loop inside a bash script.
The loop ended even if there was a lot of work to do.
And the while loop ended only when I was calling a function inside another function.

The function contained an ssh call to a remote host to get a result.
Such ssh connection, opening a shell on the remote host, maybe killed my while environment?

The solution:

remote() {
  echo -e "Checking if it is the first time we zfs send to remote $1"

  ssh $sshparam zfs list $1 </dev/null &>/dev/null 

  EL=$?
  if [ $EL -eq 0 ]
  then
    return 1
  else
    return 0
  fi
} 

</dev/null &>/dev/null