Cron job start and stop at certain time

Question

Is it possible to setup a cron job to work on certain days only at night, for example, the first day of each month from 03pm to 09pm?

I want to do an email campaign only at night when the server load is low.

Is it possible to run a cron job at a certain time and stop it at a certain time?

Answer 1

You could use a second cron job at 09pm to start a second program that tells the first program to terminate.

There are a number of ways to do this. One of the easiest might be to have the second program touch terminate.txt in a convenient place. On each loop of the first program, it could check for this file. If it exists, it could delete the file and gracefully exit.

Answer 2

Set up your cron job to run at desired time every day. Then add a test command to check if it is a first day of the month.

• Make sure your script only processes certain chunk of work and then exits on its own.
• Make sure that the script verifies that only one instance of itself is running.

So your cron job entry would be something like this:

* 15-20 * * * test `date +\%d` == 01 && script_name.sh

The script will be started at every minute between 3:00 pm and 8:59 pm (inclusive).

Answer 3

Not really. You could probably set something up to terminate a running script after six hours, but that usually wouldn't be a good solution because your script has no chance of cleaning things up.

The best thing to do would be to do a clean exit from inside the script when the time limit has been reached.

Answer 4

You can schedule cron to start your program on the first day of the month at 3PM. Your program will have to take care of killing itself at 9PM.

http://en.wikipedia.org/wiki/Cron