If you are like me, you have to dig through some log files to research some errors.  The ../var/nagios.log file has alot of data and unfortunately the times stamps are not exactly friendly to read.

[1256314960] EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT;hostname;servicename;0;Service running OK

Using a little perl command line magic we can convert that ugly timestamp into something more readable.

[Fri Oct 23 11:22:40 2009] EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT;hostname;servicename;0;Service running OK

Just use...

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

Of course that will spew the entire log.  So using grep or tail, you can make it a bit more useful.

perl -pe 's/(\d+)/localtime($1)/e' nagios.log |grep server1

tail nagios.log | perl -pe 's/(\d+)/localtime($1)/e'