How to execute recurring Bash script at specific times?

Question

How would I set a script to execute on every Tuesday and Thursday at 11:50am?

I've been looking at the at command, but I can't conceive how to use it the way I need to from its man page.

Solution

at is excellent tool for one-off commands. To run a program repetitively at the same times, however, the right tool is cron. Run crontab -e. It will open an editor. Add this line and save the file:

50 11 * * 2,4 /path/to/script

This will run /path/to/script every Tuesday and Thursday at 11:50am. crontab runs programs in a limited environment. So, script may need to set its own PATH, etc.

If the machine has a properly set up mail server, any output from script will be e-mailed to the user who owns the crontab file. Alternatively, output will be mailed to the address specified by the MAILTO variable in the crontab file. See man 5 crontab for details.

The first five columns of the line above define the time that the program is run. Their meaning is documented in man 5 crontab to be:

          field          allowed values
          -----          --------------
          minute         0-59
          hour           0-23
          day of month   1-31
          month          1-12 (or names, see below)
          day of week    0-7 (0 or 7 is Sun, or use names)

Comments

[jasonwryan]

Depending on your intit system, you could also use a systemd.timer...