Shell Programming and Scripting

What keeps you from plainly trying Don Cragun's simple proposal?

Code:

minute hour 1-7 3,6,9,12 0 command_string

Anyone would know a reason why this wouldn't do it? Since the day of the week is set as 0 (Sun) and the days of the month are 1 through 7 (for the first week), wouldn't 0 negate already any day that is not Sunday, out of those first seven days?

man crontab :

Since minute hour 1-7 3,6,9,12 0 command_string would run every day from 1 to 7 and also every Sunday, perhaps this might do it.

Code:

minute hour * 3,6,9,12 0 [ $(/usr/bin/date +%e) -le 7 ] && /path/to/script

Yes, this would do it. But it might be a bit "tidier" (for lack of a better word) to have everything in one place (like the scripts text) than spread over several places (part of the logic in cron, part of the logic in the script. If you put [ $(/usr/bin/date +%e) -le 7 ] && into the scripts text or into the commandline of the cron command should (otherwise) make no big difference.

At least this is my personal POV on the matter and maybe only makes sense because of the acquired style i work in. Technically there is no real difference and with another way of doing things the opposite may make equal sense.

I hope this helps.

bakunin

Glad you mentioned that it was your opinion, since it is debatable. I could make the argument that since the time when it runs is related to the cron job, separating the actual work from it (the script) is more logical, in that way if I decided to run it the first Sunday and the third Sunday, I do not have to get involved with the script, but rather the facility that deals with the time. Also, if I am not who created the script and I am administering an issue in the box, related to this particular run job, I could right away see what and when it is trying to run, without having to delve into any script to find out. Now, this is my reasoning.

I'll go with Bakunin

If you can not instantly decipher the purpose of command in cron, that code should be in script.
In this case i would use a case condition in script.
Alternatively you could be passing argument in cron to script with desired condition ($1) which one could change in crontab directly.

This is just my opinion and has nothing to do with right and wrong.

Best regards
Peasant.