[unix-history] / usr / src / usr.sbin / cron / cron.8

.\"	@(#)cron.8	5.1 (Berkeley) %G%
.\"
.TH CRON 8  "4 February 1983"
.AT 3
.SH NAME
cron \- clock daemon
.SH SYNOPSIS
.B /etc/cron
.SH DESCRIPTION
.I Cron
executes commands at specified dates and times
according to the instructions in the file
/usr/lib/crontab.
Since
.I cron
never exits,
it should only be executed once.
This is best done by running
.I cron
from the initialization
process through the file
/etc/rc;
see
.IR init (8).
.PP
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.
.PP
Crontab is examined by
.I cron
every minute.
.SH FILES
/usr/lib/crontab
Commit	Line	Data
aa99000f	1	.\" @(#)cron.8 5.1 (Berkeley) %G%
44828dbf	2	.\"
aa99000f	3	.TH CRON 8 "4 February 1983"
44828dbf KM	4	.AT 3
	5	.SH NAME
	6	cron \- clock daemon
	7	.SH SYNOPSIS
	8	.B /etc/cron
	9	.SH DESCRIPTION
	10	.I Cron
	11	executes commands at specified dates and times
	12	according to the instructions in the file
	13	/usr/lib/crontab.
	14	Since
	15	.I cron
	16	never exits,
	17	it should only be executed once.
	18	This is best done by running
	19	.I cron
	20	from the initialization
	21	process through the file
	22	/etc/rc;
	23	see
	24	.IR init (8).
	25	.PP
	26	Crontab
	27	consists of lines of six fields each.
	28	The fields are separated by spaces or tabs.
	29	The first five are integer patterns to
	30	specify the
	31	minute (0-59),
	32	hour (0-23),
	33	day of the month (1-31),
	34	month of the year (1-12),
	35	and day of the week (1-7 with 1=Monday).
	36	Each of these patterns may
	37	contain a number in the range above;
	38	two numbers separated by
	39	a minus
	40	meaning a range inclusive;
	41	a list of numbers separated by
	42	commas meaning any of the numbers;
	43	or an asterisk meaning all legal values.
	44	The sixth field is a string
	45	that is executed by the Shell at the
	46	specified times.
	47	A percent character
	48	in this field is translated to a new-line
	49	character.
	50	Only the first line (up to a % or end of line)
	51	of the command field is executed by the Shell.
	52	The other lines are made available to the
	53	command as standard input.
	54	.PP
	55	Crontab is examined by
	56	.I cron
	57	every minute.
	58	.SH FILES
	59	/usr/lib/crontab