etccronallow
Explanation:
The /etc/cron.d/cron.allow file is a text file that contains the names of the users who are allowed to use the crontab command to create and manage their own cron jobs12. If this file exists, only the users listed in it can use the crontab command, and all other users are denied access12. If this file does not exist, the /etc/cron.d/cron.deny file is checked to see which users are not allowed to use the crontab command12. If neither file exists, only the root user can use the crontab command12.
To modify the /etc/cron.d/cron.allow file, the root user can use any text editor to add or remove the names of the users who will be allowed to use the crontab command1234. For example, to allow the user frank to use the crontab command, the root user can append the name frank to the /etc/cron.d/cron.allow file1234. The root user must always be included in this file, otherwise the superuser access to the crontab command will be denied4.