Job Scheduling

Job Scheduling #

Job scheduling and execution is taken care of by two service daemons:

  • at (1) - queue, examine, or delete jobs for later execution
  • atd (8) - run jobs queued for later execution
  • cron (8) - daemon to execute scheduled commands
  • crond (8) - daemon to execute scheduled commands
[root@server1 ~]# ls -ld /etc/{at,cron}*
-rw-r--r--. 1 root root   1 Apr  4  2022 /etc/at.deny
drwxr-xr-x. 2 root root  21 Feb 16 09:08 /etc/cron.d
drwxr-xr-x. 2 root root   6 Mar 23  2022 /etc/cron.daily
-rw-r--r--. 1 root root   0 Jul 11  2022 /etc/cron.deny
drwxr-xr-x. 2 root root  22 Mar 23  2022 /etc/cron.hourly
drwxr-xr-x. 2 root root   6 Mar 23  2022 /etc/cron.monthly
-rw-r--r--. 1 root root 451 Mar 23  2022 /etc/crontab
drwxr-xr-x. 2 root root   6 Mar 23  2022 /etc/cron.weekly

By default all users are allowed to schedule jobs with the at and cron services, but this can be controlled with the /etc/at.{allow,deny} and /etc/cron.{allow,deny} files specifically.

at #