Each user has their own crontab, and com- mands in any given crontab will be executed as the user who owns the crontab. Blank lines and leading spaces and tabs are ignored. Note that comments are not allowed on the same line as cron commands, since they will be taken to be part of the command. Similarly, comments are not allowed on the same line as environment variable settings. 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.
Ranges of numbers are allowed. Ranges are two numbers separated with a hyphen. The specified range is inclu- sive. Lists are allowed. Step values can be used in conjunction with ranges.