I want to make a crontab entry which will run on every weekday except the 1st, 2nd, and 3rd of each month. Here’s what I have:
45 8,12,16 4-31 * 1-5 my_program
I thought that this had the following meaning:
minutes: 45 past the hour hours: 8, 12, and 16 day of month: 4th to 31st inclusive month: all day of week: Monday to Friday inclusive
That is what I read in the crontab(5) manual page. However, I can see that the job ran at 08:45 today, Monday 2nd October. I am certain the crontab file was loaded correctly (and crontab -l shows it); it wasn’t changed recently. The system date and time as shown by date is also correct.
What am I missing to make sure my cron job only runs from the 4th onwards? I am using Fedora Linux:
% rpm -qf `which crontab` cronie-1.5.0-3.fc23.x86_64 % rpm -q fedora-release fedora-release-23-1.noarch
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Answer
From crontab manual:
Note: The day of a command’s execution can be specified by two fields — day of month, and day of week. If both fields are restricted (i.e., aren’t *), the command will be run when either field matches the current time. For example, “30 4 1,15 * 5” would cause a command to be run at 4:30 am on the 1st and 15th of each month, plus every Friday. One can, however, achieve the desired result by adding a test to the command (see the last example in EXAMPLE CRON FILE below).
The mentioned example looks like this:
0 4 8-14 * * test $(date +%u) -eq 6 && echo "2nd Saturday"
So in your case it would be like this (not tested):
45 8,12,16 4-31 * * test $(date +%u) -lt 6 && my_program