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)

Answer 2

Your Cron job description looks different from the general crontab. But to give you an idea of how to achieve what you're looking for:

1. Edit cron-table. Choose your editor.

crontab -e

2. Add 2 lines cron jobs.

* 4 * * 1-5 /usr/bin/...# Your command goes here 04:00 am.
* 16 * * 1-5 /usr/bin/...# Your command goes here 04:00 pm.

Answer 3

4PM (16:00): 0 16 * * MON-FRI
See crontab guru
"At 16:00 on every day-of-week from Monday through Friday.”

4AM &4 PM (4:00 & 16:00): 0 4,16 * * MON-FRI
See crontab guru
“At minute 0 past hour 4 and 16 on every day-of-week from Monday through Friday.”