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CRONTAB(1)							    CRONTAB(1)

NAME    [Toc]    [Back]

     crontab - user crontab file

SYNOPSIS    [Toc]    [Back]

     crontab [file]
     crontab -r	[file]
     crontab -l	[file]
     crontab -e	[file]

DESCRIPTION    [Toc]    [Back]

     crontab copies the	specified file,	or standard input if no	file is
     specified,	into a directory that holds all	users' crontabs.  The -r
     option removes a user's crontab from the crontab directory.  crontab -l
     will list the crontab file	for the	invoking user. The -e option spawns an
     editor which contains the user's current crontab (as output by crontab
     -l), and automatically updates the	crontab	when the user saves the	file
     and exits the editor. The name of the editor to invoke can	be specified
     by	the environment	variable VISUAL	or EDITOR; else, vi is used by

     Normal users may only remove, list, or edit their own crontab files which
     is	the default.  The superuser (root) may supply any username following
     -r, -l, or	-e to remove, list, or edit that user's	crontab.

     If	the file /etc/cron.d/cron.allow	exists,	only users whose names appear
     in	the file are permitted to use crontab. This restriction	applies	to all
     users, including root.  If	that file does not exist, the file
     /etc/cron.d/cron.deny is checked to determine if the user should be
     denied access to crontab. If neither file exists, only root is allowed to
     submit a job.  If cron.allow does not exist and cron.deny exists but is
     empty, global usage is permitted.	The allow/deny files consist of	one
     user name per line.

     A crontab file consists of	lines of six fields each.  The fields are
     separated by spaces or tabs.  The first five are integer patterns that
     specify the following:

	  minute (0-59),
	  hour (0-23),
	  day of the month (1-31),
	  month	of the year (1-12),
	  day of the week (0-6 with 0=Sunday).

     Each of these patterns may	be either an asterisk  (meaning	all legal
     values) or	a list of elements separated by	commas.	 An element is either
     a number or two numbers separated by a minus sign (meaning	an inclusive
     range).  Note that	the specification of days may be made by two fields
     (day of the month and day of the week).  If both are specified as a list
     of	elements, both are adhered to.	For example, 0 0 1,15 *	1 would	run a
     command on	the first and fifteenth	of each	month, as well as on every
     Monday.  To specify days by only one field, the other field should	be set
     to	* (for example,	0 0 * *	1 would	run a command only on Mondays).

									Page 1

CRONTAB(1)							    CRONTAB(1)

     The sixth field of	a line in a crontab file is a string that is executed
     by	the shell at the specified times.  A percent character in this field
     (unless escaped by	\) 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

     The shell is invoked from your $HOME directory with an arg0 of sh.	 Users
     who desire	to have	their .profile executed	must explicitly	do so in the
     crontab file.  Cron supplies a default environment	for every shell,
     defining HOME, LOGNAME, USER, SHELL(=/bin/sh),
     PATH(=/usr/sbin:/usr/bsd/:/usr/bin:/bin/:/etc:/usr/etc), and TZ.

     If	you do not redirect the	standard output	and standard error of your
     commands, any generated output or errors will be mailed to	you.

     Any errors	encountered while parsing the crontab file (or stdin) will
     cause crontab to abort with no changes being made to any existing

FILES    [Toc]    [Back]

     /etc/cron.d		main cron directory
     /var/spool/cron/crontabs	spool area
     /var/cron/log		accounting information
     /etc/cron.d/cron.allow	optional list of allowed users
     /etc/cron.d/cron.deny	list of	denied users
     /etc/cron.d/FIFO		to communicate crontab changes to cron

SEE ALSO    [Toc]    [Back]

     sh(1), cron(1M)

NOTES    [Toc]    [Back]

     If	you inadvertently enter	the crontab command with no argument(s), you
     may exit without overwriting the existing crontab entry either by
     generating	an interrupt (typically	by typing ^C or	DEL), or by providing
     empty input (typically by typing ^D on the	first empty line).

     If	a job is scheduled during the 'witching	hour' -	the time during	a
     change from the main to alternate time zone, the job will either be run
     once (if the actual time exists twice) or not at all (if the actual time
     never exists).

									PPPPaaaaggggeeee 2222
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