List cron for a specific user:

crontab -u username -l

List crons for every user

for user in $(cut -f1 -d: /etc/passwd); do echo -$user-; crontab -u $user -l; done

for cron in `ls -1 /var/spool/cron/crontabs/`; do echo "${cron}'s crontab";crontab -l -u $cron | grep -v '#' ;echo;done

Viewing Cron Start Time

date; echo; ps -ef --sort=start_time | grep php | head -n 15