An active line in a crontab will be either an environment setting or a cron command. Otherwise mail is sent to the owner of the crontab. The format of a cron command is very much the V7 standard, with a number of upward-compatible extensions. Each line has five time and date fields, followed by a user name if this is the system crontab file, followed by a command. Ranges of numbers are allowed.
Ranges are two numbers separated with a hyphen.
The specified range is inclusive. Lists are allowed. Step values can be used in conjunction with ranges. Ranges or lists of names are not allowed. When specifying day of week, both day 0 and day 7 will be considered Sunday.