crontab header for reminder

crontab_header

#┌──────────────────────────────────────── minutes: 0-59, */2 every 2 minutes
#│ ┌────────────────────────────────────── Hours: 0-23
#│ │ ┌──────────────────────────────────── Day: 1-31
#│ │ │ ┌────────────────────────────────── Month: 1-12
#│ │ │ │ ┌──────────────────────────────── WeekDay: 0-7; Sunday=0, Saturday=6
#│ │ │ │ │  ┌───────────────────────────── user which will exec the command (can be not supported on somes systems)
#│ │ │ │ │  │
#* * * * * user command to execute
#eg: execute backup at 2h30 and 14h30 from monday to friday
#30 2,14 * * 1-5 root /usr/local/sbin/backup.sh