v7 man page for cron

CRON(8) 						      System Manager's Manual							   CRON(8)

NAME
       cron - clock daemon

SYNOPSIS
       /etc/cron

DESCRIPTION
       Cron executes commands at specified dates and times according to the instructions in the file /usr/lib/crontab.	Since cron never exits, it
       should only be executed once.  This is best done by running cron from the initialization process through the file /etc/rc; see init(8).

       Crontab consists of lines of six fields each.  The fields are separated by spaces or tabs.  The first five are integer patterns to  specify
       the  minute (0-59), hour (0-23), day of the month (1-31), month of the year (1-12), and day of the week (1-7 with 1=monday).  Each of these
       patterns may contain a number in the range above; two numbers separated by a minus meaning a range inclusive; a list of	numbers  separated
       by  commas  meaning any of the numbers; or an asterisk meaning all legal values.  The sixth field is a string that is executed by the Shell
       at the specified times.	A percent character in this field is translated to a new-line character.  Only the first line (up to a % or end of
       line) of the command field is executed by the Shell.  The other lines are made available to the command as standard input.

       Crontab is examined by cron every minute.

FILES
       /usr/lib/crontab

																	   CRON(8)