CRON Question
 

How can I run cron on the 1st hr, 2nd hr, 4th hr...in a 24 hour period, everyday, every month, every year?

http://en.wikipedia.org/wiki/Cron

Generally by using @hourly or "0 * * * *" in your crontab file.

The "0" says "every time the minute is :00" which of course works out to hourly. But if you want to run it 30 minutes past the hour every hour you might do "30 * * * *", for example.

See the wiki article for more details. :)

I found my answer there!!

0 */2 * * * /home/user/jim/test.pl
0 */3 * * * /home/user/jim/test.pl
0 */4 * * * /home/user/jim/test.pl

Thanks!!

Oh that's what you wanted?

Just to make sure it is:

Means every other hour.

Every 3 hours.

Every 4 hours. :)

The following line causes the user program test.pl – possibly a Perl script – to be run every two hours, namely at midnight, 2am, 4am, 6am, 8am, and so on:

0 */2 * * * /home/user/jim/test.pl


oh no I guess it's not what I wanted... :L

I need it to run like this:

1:00 /home/user/jim/test.pl
2:00 /home/user/jim/test2.pl
3:00 /home/user/jim/test3.pl
4:00 /home/user/jim/test4.pl

and so forth

so would it be like this?

0 0/1 * * * /home/user/jim/test.pl
0 0/2 * * * /home/user/jim/test2.pl
0 0/3 * * * /home/user/jim/test3.pl

Just three different scripts then? There are different ways to go but in a pinch perhaps this might work:

0 1 * * * /home/user/jim/test.pl
0 2 * * * /home/user/jim/test2.pl
0 3 * * * /home/user/jim/test3.pl
0 4 * * * /home/user/jim/test.pl
0 5 * * * /home/user/jim/test2.pl

and so on.

In this example:

test.pl would run at 1am and 4am.
test2.pl would run at 2am and 5am
test3.pl would run at 3am.

Another way of doing the above (same thing) would be:

0 1,4 * * * /home/user/jim/test.pl
0 2,5 * * * /home/user/jim/test2.pl
0 3 * * * /home/user/jim/test3.pl

... but there are all sorts of ways to do it. :)

You'll probably want to redirect the output in some way too.

Also see this: http://www.tutorial5.com/content/view/95/51/
It's a decent tutorial which may be of some help.

You can type 'man crontab' at the command line to see the man page as well.

And to make it more clear if you were just wanting a different script for each hour of the day I guess you could do something like:

0 1 * * * /home/user/jim/test.pl >/dev/null 2>&1
0 2 * * * /home/user/jim/test2.pl >/dev/null 2>&1
0 3 * * * /home/user/jim/test3.pl >/dev/null 2>&1

...

0 23 * * * /home/user/jim/test23.pl >/dev/null 2>&1

The ">/dev/null 2>&1" at the end says to discard the output so that it doesn't email it to you for each hour.

Hope this helps.

That's exactly what I want it to do, to run different scripts every hour of the day. I'll give it a shot. Thank you! :)