Cron to run a Perl script

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Cron to run a Perl script by johngg (Canon) on Dec 09, 2015 at 14:27 UTC
Rather than trying to get `cron` jumping through hoops, it would be much easier to invoke the script via `cron` every third weekday then inside the script test if it is the first week and bail if not. Get epoch seconds from time, calculate epoch seconds a week ago by subtracting `86400 * 7` seconds then use Time::Local`::timelocal()` to get the month number from each one; if the month isn't different you are not in the first week. I hope this is helpful. Update: A general note of caution with this approach, if your `cron` job is running an hour either side of midnight then beware of daylight savings changes in case they throw the calculations off. I've been bitten on the bum by that :-) Cheers, JohnGG	[reply] [d/l] [select]
Re: Cron to run a Perl script by Corion (Patriarch) on Dec 09, 2015 at 14:37 UTC
Why not have the script exit unless it is run on a Wednesday, and then launching the script on the days 1 to 7 of the month?	[reply]
Re: Cron to run a Perl script by Maresia (Beadle) on Dec 09, 2015 at 19:26 UTC
Had similar problem before, this will run every first Monday of every month: `0 12 1-7 * * [ "$(date '+\%a')" = "Mon" ] && /script/script.pl` [download] I hope it helps!	[reply] [d/l]
Re: Cron to run a Perl script by GotToBTru (Prior) on Dec 09, 2015 at 16:45 UTC
If I understand you correctly, you'd want the job to run on Jan 5, Feb 3, Mar 3, Apr 5, May 4 those being the third weekday of the first week of the next few months. If not, please supply the list of actual dates you're looking for. Dum Spiro Spero	[reply]
Re^2: Cron to run a Perl script by Anonymous Monk on Dec 09, 2015 at 18:58 UTC
I meant every third weekday or every Wednesday of the first week of every month. Thanks!	[reply]
Re^3: Cron to run a Perl script by GotToBTru (Prior) on Dec 09, 2015 at 19:17 UTC
So which is it .. every third weekday or every Wednesday? If you would supply the dates, as I did, your meaning would be obvious. Dum Spiro Spero	[reply]
Re^4: Cron to run a Perl script by Anonymous Monk on Dec 09, 2015 at 19:43 UTC
Re^5: Cron to run a Perl script by GotToBTru (Prior) on Dec 09, 2015 at 19:47 UTC
Re: Cron to run a Perl script by Discipulus (Canon) on Dec 10, 2015 at 10:05 UTC
I prefere the Corion's solution even if it has a drowback: when you lately inspect the cron schedules you not see the real runs. You can workaround this using a self explaining named argument to the final script or, if frequently used, a dedicated minimodule: `0 7 * * 3 /script/script.pl --run_only_on_wednesdays #or 0 7 * * 3 perl -MExitUnlessWednsday script/script.pl` [download] L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l]