linux - Running a cron at 4 am and 4 pm

Question

The following cron expression cron(0 14 ? * MON-FRI *) basically runs something 4:00 pm from Monday to Friday.

I am wondering if it is possible to modify the expression so I can run something at 4:00 am and 4:00 pm every Monday to Friday.

Answer 1

Use this crontab line to run command_name at 4:00 and 16:00 (4 AM and 4 PM) Monday-Friday:

0 4,16 * * 1-5 command_name

From crontab manual:

   The time and date fields are:

          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 Sunday, or use names)