Get updates via: rss | twitter | email | google+

Run a program or script every 5 or X minutes or hours

Written by Guillermo Garron .
Date: 2012-04-07 09:33:00 -0400

One of the best things computers do, is to execute repetitive jobs, and with *nix systems that is done using cronjob.

I usually want my jobs to run every X amount of time, let’s say every 5 minutes, or every 12 hours.

Here is how:

If you want to do it every 12 hours, add this line when editing crontab file.

0 */12 * * * /path/to/script-or-program

That will run on 12 and 0 hours, at 0 seconds.

Of course you can combine.

*/5 */3 * * * /path/to/script-or-program

This will execute every five minutes, only on hours 3, 6, 9, 12 and so on.

If you use that in day of month field, you can end up running your script every X days in a month, but then X-1 or X+1 when changing months, from even to odd days months.

So:

0 0 */2 * * * /path/to/script-or-command

Would result in every two days until the end of the month and then a three day interval when the next month is starting.

Using the method with months of year, can also lead to similar problems.

0 10 01 */3 * /path/to/script-or-program

Will run the command every three months on the first day at 10:00, so, 10:00 first of Jan, Apr, Jul, Oct.

But if you use an interval that does not divid the year in equal parts, like 5.

0 10 01 */5 * /path/to/script

The script will run at 10:00 first day of Jan, Jun, Dec and then Jan again, only one month after the last time.


permalink

If you enjoyed the article, please share it

twitter | facebook | google+ | linkedin | email | reddit


You may want to subscribe to my newsletter

If you want to receive articles similar to this every month sign in to our Newsletter and joing other 2.000 readers

You can see an example of what is going to be sent to you here

powered by TinyLetter