On Wed, 9 Nov 2011, Joao Paulo Saldanha wrote:

Please, I need help setting up a cron to run rsync every 3 hours. Can someone help me create this?

Wait. Thank.

Joao,

To run a program every 3 hours, use an entry like this: 0 */3 * * * /run/this/program

Cron will run the program when all the fields match.

More explanation (from "man 5 crontab"):

The time and date fields are:

field allowed values ----- -------------- minute 0-59 hour 0-23 day of month 1-31 month 1-12 (or names, see below) day of week 0-7 (0 or 7 is Sun, or use names)

A field may be an asterisk (*), which always stands for "first-last".

Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen. The specified range is inclusive. For example, 8-11 for an "hours" entry specifies execution at hours 8, 9, 10 and 11.

Lists are allowed. A list is a set of numbers (or ranges) separated by commas. Examples: "1,2,5,9", "0-4,8-12".

Step values can be used in conjunction with ranges. Following a range with "<number>" specifies skips of the numberâs value through the range. For example, "0-23/2" can be used in the hours field to specify command execution every other hour (the alternative in the V7 standard is "0,2,4,6,8,10,12,14,16,18,20,22"). Steps are also permitted after an asterisk, so if you want to say "every two hours", just use "*/2".

Hope this helps, DR