Readable Nagios Log Timestamps

If you’re like me and most humans, the Nagios logfile timestamp (a unix timestamp) isn’t terribly useful when trying to grep through the logs and correlate events:

# head -2 nagios.log
[1350360000] LOG ROTATION: DAILY
[1350360000] LOG VERSION: 2.0

Here’s a nifty Perl one-liner that you can pipe your logs through:

perl -pe 's/(\\d+)/localtime($1)/e'  

to get nicer output like:

# head -2 nagios.log
[Tue Oct 16 00:00:00 2012] LOG ROTATION: DAILY
[Tue Oct 16 00:00:00 2012] LOG VERSION: 2.0