Cron on Monday, Wednesday and Friday
List the weekdays in the 5th field: 1,3,5 means Monday, Wednesday and Friday. Cron numbers days 0 (Sun) to 6 (Sat), and 7 is Sunday too.
The crontab line
0 9 * * 1,3,5 /path/to/job.sh
The comma list 1,3,5 picks Monday, Wednesday and Friday. Change 0 9 for a different time.
Day numbers
Cron day-of-week: 0=Sun, 1=Mon, 2=Tue, 3=Wed, 4=Thu, 5=Fri, 6=Sat. You can also write MON,WED,FRI.
Every other weekday
For a stepped pattern within the week use a range with a step, e.g. * * * * 1-5/2 — but explicit lists like 1,3,5 are clearer and less error-prone.
FAQ
What is the cron for Monday Wednesday Friday?
Use 0 9 * * 1,3,5 to run at 09:00 on Mon, Wed and Fri. The 1,3,5 in the day-of-week field selects those days.
Can I use day names instead of numbers?
Yes. 0 9 * * MON,WED,FRI works in Vixie cron and is equivalent to 1,3,5.
What number is Monday in cron?
Monday is 1. Days run 0 (Sunday) through 6 (Saturday), and 7 also means Sunday.