Re: Run a command on "last day of month"

On 9/1/21 5:50 AM, Joel Carnat wrote:
> Hello,
>
> I would like to run a command on "the last day of each month".
>
> From what I understood reading the crontab(5) manpage, the simplest way
> would be setting day-of-month to "28-31". But this would mean running
> the command 4 times for months that have 31 days.
>
> Is there a simpler/better way to configure crontab(1) to run a command
> on "the last day of month" only ?
>
> Thank you,
> Joel C.
>

Just run your script every day, and first thing in the script, check to see
if it is the last day of the month -- and quickly exit if it isn't. Very
cheap to do and relatively easy if you know a good trick to do it.

http://holland-consulting.net/scripts/endofmonth.html

Find the last day of the month:
$ set $(cal)
$ shift $(($# - 1))
$ echo $1
30

Compare to today:
$ date "+%d"
1

rather easy, and fairly portable.
You could probably stuff it into a one-liner in a crontab, but I would not
recommend it.


Nick.