cronjob service Verify on RHEL / CentOS / Fedora Linux,

--You can simply use any one of the following command to see if crond is running or not, enter:
# pgrep crond
OR
# service crond status
Sample output:

--crond (pid 4370) is running...If it is not running type the following two command to start crond:
# chkconfig crond on
# service crond start
--Verify cron is running by viewing log file, enter:
# tail -f /var/log/cron
--A note about Debian / Ubuntu Linux Cron service
--Under Debian and Ububtu Linux cron logs its action logged to the syslog facility i.e. use /var/log/messages file:
# tail -f /var/log/messages
--Find out if cron daemon is running or not, enter:
# pgrep cron