How can I set a cron and how can I execute it in Linux?

abhik · 05-27-2016, 02:12 AM

pan64 · 05-27-2016, 02:14 AM

man crontab ?
man cron ?

Turbocapitalist · 05-27-2016, 03:09 AM

Quote:

Originally Posted by pan64

man crontab ?
man cron ?

The file format is described in section number 5, and the program itself is described in section number 1. So, "man crontab" by itself will find the section 1 page only, since it is the first. But section 5 is where you'll find the necessary information about how to structure the crontab itself. You'll have to tell "man" explicitly to show the section 5 page, compare:

Code:

man crontab
man 1 crontab
man 5 crontab
man man

One tip is that if you are trying to run a complex chain of programs, it is easier to put them into a script and then call the script from cron.

HMW · 05-27-2016, 04:26 AM

Agreed to what has already been posted. Also, not all GNU/Linux distributions have cron installed by default (Arch Linux for instance).

Best regards,
HMW

thorkelljarl · 05-27-2016, 04:55 AM

Note...

If you want to use crontab to run commands requiring root, such as shutdown, you may be required to become root before using crontab. I found using su is not sufficient.

You may then have two crontab files with two instances of the cron function running, one set up to run commands requiring root and another for any other command, such as playing a video file at a set time, that you would not want to run as root.