Syntax of crontab File Entries

A crontab file consists of commands, one command per line, that execute automatically at the time specified by the first five fields of each command line. These five fields, described in the following table, are separated by spaces.

Follow these guidelines for using special characters in crontab time fields:

• Use a space to separate each field.

• Use a comma to separate multiple values.

• Use a hyphen to designate a range of values.

• Use an asterisk as a wildcard to include all possible values.

• Use a comment mark (#) at the beginning of a line to indicate a comment or a blank line.

For example, the following crontab command entry displays a reminder in the user's console window at 4 p.m. on the first and fifteenth days of every month.

0 16 1,15 * * echo Timesheets Due > /dev/console

Each command within a crontab file must consist of one line, even if that line is very long. The crontab file does not recognize extra carriage returns. For more detailed information about crontab entries and command options, refer to the crontab(1) man page.