On Fedora based system, whenever I need help writing a cron task and confused which field is minute, hour, day,..etc, I usually check the /etc/crontab file.

❯ cat /etc/crontab 
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed

Recently, I found an online cron scheduler editor - crontab.guru. It can be used to create a new task expression, or we can use it to verify the existing cron schedule expressions that we have.

I find this free service very useful.

Read more: