Does cron expression in unix/linux allow specifying exact start and end dates

Question

I want to be able to configure something like this.

1. I want to run job 'X' at 7 AM everyday starting from 29/june/2009 till 30/12/2009. Consider current date as 4/4/2009.

Answer 1

It can be done in a tricky sort of way.

You need three separate cron jobs for that range, all running the same code (X in this case):

• one for the 29th and 30th of June ("0 7 29,30 6 * X").
• one for every day in the months July through November ("0 7 * 7-11 * X").
• one for all but the last day in December ("0 7 1-30 12 * X").

This gives you:

# Min   Hr   DayOfMonth   Month   DayOfWeek   Command
# ---   --   ----------   -----   ---------   -------
   0     7      29,30        6        *          X
   0     7          *     7-11        *          X
   0     7       1-30       12        *          X

Then make sure you comment them out before June 29, 2010 comes around. You can add a final cron job on December 31 to email you that it needs to be disabled.

Or you could modify X to exit immediately if the year isn't 2009.

if [[ "$(date +%Y)" != "2009" ]] ; then
    exit
fi

Then it won't matter if you forget to disable the jobs.