gno/usr.sbin/cron/cron.8
1998-03-09 15:50:56 +00:00

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CRON(8) UNIX Programmer's Manual CRON(8)
NAME
cron - clock daemon
SYNOPSIS
/usr/sbin/cron
DESCRIPTION
Cron executes commands at specified dates and times accord-
ing to the instructions in the file /etc/crontab (if it exists).
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/inittab; see init(8).
The crontab file consists of lines of seven fields each.
The fields are separated by spaces or tabs. The first five
are integer patterns to specify:
o+ minute (0-59)
o+ hour (0-23)
o+ day of the month (1-31)
o+ month of the year (1-12)
o+ day of the week (1-7 with 1 = Monday)
Each of these patterns may contain:
o+ a number in the range above
o+ two numbers separated by a minus meaning a range inclusive
o+ a list of numbers separated by commas meaning any of the
numbers
o+ an asterisk meaning all legal values
The sixth field is a user name: the command will be run with
that user's uid and permissions. The seventh field consists
of all the text on a line following the sixth field, includ-
ing spaces and tabs; this text is treated as a command which
is executed by the Shell at the specified times. A percent
character (``%'') in this field is translated to a new-line
character.
The crontab file is checked by cron every minute, on the
minute.
FILES
/etc/crontab