SNMP Alarm Support

I think `[ -z ... ] && ...` is dangerous.  Although this file has no `set -e` in, if it had then `[ -z ... ] && ...` would fail (and hence terminate the script) if `$snmp_ip` was not defined.  Writing `[ -z ... ] || ...` ensures that the statement is always true (as the latter part is always true), meaning that we'll never terminate the script.