Since cron runs jobs time-based, not interval-based, there’s no blindingly simple way to do it. However, although it’s a bit of a hack, you can set up multiple lines in crontab until you find the common denominator. Since you want a job to run every 72 minutes, it must execute at the following times: 00:00 … Read more
In Vixie cron, which is possibly the most common, you can do this almost exactly like a shell script. VARIABLE=value PATH=/bin:/path/to/doathing 0 0 * * * doathing.sh $VARIABLE The man page says: An active line in a crontab will be either an environment setting or a cron command. An environment setting is of the form, … Read more
Cron utility is an effective way to schedule a routine background job at a specific time and/or day on an on-going basis. Linux Crontab Format MIN HOUR DOM MON DOW CMD Example::Scheduling a Job For a Specific Time The basic usage of cron is to execute a job in a specific time as shown below. … Read more
To run a task every 20 minutes starting at 5 past the hour, try this: 5-59/20 * * * * Explanation An * in the minute field is the same as 0-59/1 where 0-59 is the range and 1 is the step. The command will run at the first minute in the range (0), then … Read more
That’s not possible with a single expression in normal cron. The best you could do without modifying the code is: 0 0,3,6,9,12,15,18,21 * * * [cmd] 30 1,4,7,10,13,16,19,22 * * * [cmd] These might be compressible, depending on the version of cron you have to: 0 */3 * * * [cmd] 30 1-23/3 * * … Read more
Run it every three days… 0 0 */3 * * How about that? If you want it to run on specific days of the month, like the 1st, 4th, 7th, etc… then you can just have a conditional in your script that checks for the current day of the month. if (((date(‘j’) – 1) % … Read more
From here: Cron also supports ‘step’ values. A value of */2 in the dom field would mean the command runs every two days and likewise, */5 in the hours field would mean the command runs every 5 hours. e.g. * 12 10-16/2 * * root backup.sh is the same as: * 12 10,12,14,16 * * … Read more