usr/src/usr.sbin/cron/cron.8

.\"	@(#)cron.8	6.4 (Berkeley) %G%
.\"
.TH CRON 8 ""
.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 files
/usr/lib/crontab and /usr/lib/crontab.local.
None, either one, or both of these files may be present.
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
The
crontab files
consist of lines of seven fields each.
The fields are separated by spaces or tabs.
The first five are integer patterns to specify:
.in +2m
.TP 2m
\(bu
minute (0-59)
.nr .0 \n()Pu
.nr )P 0
.TP 2m
\(bu
hour (0-23)
.TP 2m
\(bu
day of the month (1-31)
.TP 2m
\(bu
month of the year (1-12)
.TP 2m
\(bu
day of the week (1-7 with 1 = Monday)
.nr )P \n(.0u
.in -2m
.LP
Each of these patterns may contain:
.in +2m
.TP 2m
\(bu
a number in the range above
.nr .0 \n()Pu
.nr )P 0
.TP 2m
\(bu
two numbers separated by a minus
meaning a range inclusive
.TP 2m
\(bu
a list of numbers separated by
commas meaning any of the numbers
.TP 2m
\(bu
an asterisk meaning all legal values
.nr )P \n(.0u
.in -2m
.LP
The sixth field is a user name: the
command will be run ``as'' that user.
The seventh field consists of all the text
on a line following the sixth field,
including 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.
.PP
Both
crontab files are checked by
.I cron
every minute, on the minute.
.SH FILES
/usr/lib/crontab
.br
/usr/lib/crontab.local
Commit	Line	Data
	1	.\" @(#)cron.8 6.4 (Berkeley) %G%
	2	.\"
	3	.TH CRON 8 ""
	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 files
	13	/usr/lib/crontab and /usr/lib/crontab.local.
	14	None, either one, or both of these files may be present.
	15	Since
	16	.I cron
	17	never exits,
	18	it should only be executed once.
	19	This is best done by running
	20	.I cron
	21	from the initialization
	22	process through the file
	23	/etc/rc;
	24	see
	25	.IR init (8).
	26	.PP
	27	The
	28	crontab files
	29	consist of lines of seven fields each.
	30	The fields are separated by spaces or tabs.
	31	The first five are integer patterns to specify:
	32	.in +2m
	33	.TP 2m
	34	\(bu
	35	minute (0-59)
	36	.nr .0 \n()Pu
	37	.nr )P 0
	38	.TP 2m
	39	\(bu
	40	hour (0-23)
	41	.TP 2m
	42	\(bu
	43	day of the month (1-31)
	44	.TP 2m
	45	\(bu
	46	month of the year (1-12)
	47	.TP 2m
	48	\(bu
	49	day of the week (1-7 with 1 = Monday)
	50	.nr )P \n(.0u
	51	.in -2m
	52	.LP
	53	Each of these patterns may contain:
	54	.in +2m
	55	.TP 2m
	56	\(bu
	57	a number in the range above
	58	.nr .0 \n()Pu
	59	.nr )P 0
	60	.TP 2m
	61	\(bu
	62	two numbers separated by a minus
	63	meaning a range inclusive
	64	.TP 2m
	65	\(bu
	66	a list of numbers separated by
	67	commas meaning any of the numbers
	68	.TP 2m
	69	\(bu
	70	an asterisk meaning all legal values
	71	.nr )P \n(.0u
	72	.in -2m
	73	.LP
	74	The sixth field is a user name: the
	75	command will be run ``as'' that user.
	76	The seventh field consists of all the text
	77	on a line following the sixth field,
	78	including spaces and tabs;
	79	this text is treated as a command
	80	which is executed by the Shell at the
	81	specified times.
	82	A percent character (``%'')
	83	in this field is translated to a new-line
	84	character.
	85	.PP
	86	Both
	87	crontab files are checked by
	88	.I cron
	89	every minute, on the minute.
	90	.SH FILES
	91	/usr/lib/crontab
	92	.br
	93	/usr/lib/crontab.local