Crontab on hourly basis

Shell Programming and Scripting
1

Hi..

I need to run the script on hourly basis.
How do I write the crontab on hourly basis i.e, 9:00, 10:00.....22:00.. 23:00 hours

Please let me know if the below is correct one for crontab on hourly basis.

00 * * * * ksh myscript.ksh > /dev/null

Regards,
John

2

It is correct.

3

here is the small explaination.

1 2 3 4 5 /root/backup.sh
 Where,
�1: Minute (0-59)
�2: Hours (0-23)
�3: Day (0-31)
�4: Month (0-12 [12 == December])
�5: Day of the week(0-7 [7 or 0 == sunday])
�/path/to/command - Script or command name to schedule
Easy to remember format:
* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)
here a good comparison table i use to make it easy Format Meaning 
0 0 1 1 * Run once a year 
0 0 1 * * Run once a month 
0 0 * * 0 Run once a week 
0 0 * * * Run once a day 
0 * * * * Run once an hour

and

@yearly (or @annually) Run once a year, midnight, Jan. 1st 0 0 1 1 * 
@monthly Run once a month, midnight, first of month 0 0 1 * * 
@weekly Run once a week, midnight on Sunday 0 0 * * 0 
@daily Run once a day, midnight 0 0 * * * 
@hourly Run once an hour, beginning of hour 0 * * * * 
@reboot Run at startup @reboot
4

If your requirement is to schedule your script to run each hour (24 times a day), then below setup is correct:

00 * * * * ksh myscript.ksh > /dev/null

But if you wan to run it only between 9:00 AM to 11:00 PM :

00 09-23 * * * ksh myscript.ksh > /dev/null

OR

00 09,10,11,12,13,14,15,16,17,18,19,20,21,22,23 * * * ksh myscript.ksh > /dev/null