[Linux] Journal.

Cron is used to automate periodic tasks. You can simply copy scripts in cron directories under /etc/cron.hourly, daily, weekly or monthly to run it at these specific intervals.

If you need finer control, as a user you can run cronstab -e which allows you to edit your own configuration file using vi. This file is stored in /var/spool/cron/crontabs/ under your user name.

The syntax of a cron file looks like:

1 2 3 4 5  /path/script args
  Where:
    1: minutes (0-59)
    2: Hours (0-23)
    3: Day     (0-31)
    4: Month   (0-12 or January, February, ... 0 and 12=December)
    5: Day of the week(0-7 or Monday, Tuesday, Wednesday, ... 0 and 7=Sunday)

You can also use wildcards:

*:         applies everytime
1-4:       start if 1,2,3 or 4 matche
1-4/2      step-by-step, here: 1 and 3
1,5,6:     enumeration
*/3:       every third
1-4,10-15: enummeration and range combined

Examples:

# every 10 minutes
*/10 * * * * /etc/job
# on weekdays at 19:00
0 19 * * 1-5   mail -s "It's 7pm watch TV"

This entry was posted on Tuesday, June 29th, 2004 at 11:10 am and is filed under Debian. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.