Crontab Format: Minute Hour Day Week Month

if you want to learn the format syntax for a crontab to work properly follow this format when editing the crontab files in your linux server:

for example, i have this:

02 4 * * * * root SomeScript /etc/mycrons

the above command begins with five fields that specify the time. the fields are:

0-59 = minute
0-23 = hour
1-31 = day
1-12 = month
0-7 = week


here is a breakdown:

* * * * * command to be executed
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)

if you had something more complicated like lets say you want to run the script on every Friday the 13th... 5 1 13 * 5 root SomeScript /etc/mycrons

5 = 5 minutes past the hour
1 = 01:00 (1am)
13 = day of the month
* = month (in this case, we leave * to ANY month)
5 = Friday

hope that helps