┌───────────── minute (0 - 59)
 │ ┌───────────── hour (0 - 23)
 │ │ ┌───────────── day of month (1 - 31)
 │ │ │ ┌───────────── month (1 - 12)
 │ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday;
 │ │ │ │ │                                       7 is also Sunday on some systems)
 │ │ │ │ │
 │ │ │ │ │
 * * * * *  schedule command to execute