Cron allows us to create scheduled tasks in Linux. It is a built-in system service that enables repetitive task execution at specified time intervals by adding custom configurations.
crontab
By executing this command, we can load our crontab file into /var/spool/cron/crontabs.
File format:
13 04 * * * Command
The first five columns from left to right represent minute, hour, day, month, and weekday respectively. The asterisk means every.
Separators:
, represents separated time points, such as: 00 10,12 * * * means 10 AM and 12 PM every day
- represents time range, for example: 00 10-12 * * * means every full hour from 10 AM to 12 PM daily
*/n represents every n units of time, such as: */5 * * * * means every 5 minutes
It’s worth noting that the executable files to be run need to use absolute paths
For example:
13 04 * * * /etc/init.d/smb restart
Common parameters
$ crontab -l // List tasks
$ crontab -r name // Delete task file
$ crontab -e // Modify and install task file, enter editor, save and exit after editing to complete successfully
If you need one-time task scheduling for a specific moment, you can use the at command.
