At the moment I’ve got a few servers to monitor and Nagios is a great tool for this task.
When I’d like to see what’s the current status of Nagios, I do
tail -f /usr/local/nagios/var/nagios.log
Then I saw
 Auto-save of retention data completed successfully.
What the heck is the number in ? Ok, it’s unixtimestamp. Because Nagios needs a unix timestamp in order to make the report work, then it makes sense.
As a Perl programmer, repution of Perl one-liner has come to be quite handy :P take a look at
tail -f /usr/local/nagios/var/nagios.log | perl -pe 's/(\d+)/localtime($1)/e'
the output has transformed to be
[Thu Jan 16 00:46:36 2014] Auto-save of retention data completed successfully.
yay! \o/ /me <- human can read it now…