How to write custom files in Pig

I have a problem with writing custom output of a pig job

I basically want to write the stats of the execution time of pig job , into a file My pig job is ready and is working.

How can I now write the stats of the execution time format : start time, end time, (end-start time) execution time

Kindly guide me as to should I try to do this with pig or write a shell script , call java code methods to do somthing for me.. Thanks in advance.. Regards