You are not allowed to use this program (crontab)

The crontab command used in unix sometimes shows the following error.

crontab -e
You (UnixUser) are not allowed to use this program (crontab)
See crontab(1) for more information

The system checks cron.allow file for allowing the user to use the crontab command. So, just add the user to the crontab.allow using the following command.

[UnixUser~]$ su
Password:
[root UnixUser]# echo UnixUser> /etc/cron.allow

Cron is driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule.