Issue
How to find cron
job modified time in Ubuntu, For Example: when the cron
job has been modified or changed.
Solution
You can check cron logs. Or you can use command
stat /var/spool/cron/www-data
This will give you modification file of the file where are stored your cron jobs
For Ubuntu 14.04 seems command needs to be
stat /var/spool/cron/crontabs/www-data
Answered By - Romeo Ninov