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CRONTAB(5)		      File Formats Manual		    CRONTAB(5)

NAME
       crontab -- tables for driving cron

DESCRIPTION
       A  crontab file contains	instructions to	the cron(8) daemon of the gen-
       eral form: ``run	this command at	this time on this date''.   Each  user
       has  their  own crontab,	and commands in	any given crontab will be exe-
       cuted as	the user who owns the crontab.	Uucp  and  News	 will  usually
       have  their  own	 crontabs, eliminating the need	for explicitly running
       su(1) as	part of	a cron command.

       Blank lines and leading spaces and tabs are ignored.  Lines whose first
       non-space character is a	pound-sign (#) are comments, and are  ignored.
       Note  that  comments are	not allowed on the same	line as	cron commands,
       since they will be taken	to be part of the  command.   Similarly,  com-
       ments  are  not	allowed	 on the	same line as environment variable set-
       tings.

       An active line in a crontab will	be either an environment setting or  a
       cron command.  An environment setting is	of the form,

	   name	= value

       where the spaces	around the equal-sign (=) are optional,	and any	subse-
       quent non-leading spaces	in value will be part of the value assigned to
       name.   The value string	may be placed in quotes	(single	or double, but
       matching) to preserve leading or	trailing blanks.  The name string  may
       also  be	 placed	 in quote (single or double, but matching) to preserve
       leading,	trailing or inner blanks.

       Several environment variables are set up	automatically by  the  cron(8)
       daemon.	SHELL is set to	/bin/sh, and LOGNAME and HOME are set from the
       /etc/passwd  line of the	crontab's owner.  In addition, the environment
       variables of the	user's login class will	be set from /etc/login.conf.db
       and ~/.login_conf.  (A setting of HOME in the login class will override
       the value from /etc/passwd, but will not	change the  current  directory
       when  the  command is invoked, which can	only be	overridden with	an ex-
       plicit setting of HOME within the crontab file itself.)	If PATH	is not
       set    by    any	   other     means,	it     is     defaulted	    to
       /sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin.	 HOME,
       PATH and	SHELL, and any variables set from  the	login  class,  may  be
       overridden by settings in the crontab; LOGNAME may not.

       (Another	 note:	the  LOGNAME  variable is sometimes called USER	on BSD
       systems...  On these systems, USER will be set also).

       If cron(8) has any reason to send mail as a result of running  commands
       in  ``this''  crontab, it will respect the following settings which may
       be defined in the crontab (but which  are  not  taken  from  the	 login
       class).	If MAILTO is defined (and non-empty), mail is sent to the user
       so  named.   If	MAILFROM is defined (and non-empty), its value will be
       used as the from	address.  MAILTO may also be used to  direct  mail  to
       multiple	 recipients  by	 separating  recipient users with a comma.  If
       MAILTO is defined but empty (MAILTO=""),	no mail	will be	sent.	Other-
       wise  mail  is sent to the owner	of the crontab.	 This option is	useful
       if you decide on	/bin/mail instead of /usr/lib/sendmail as your	mailer
       when  you install cron -- /bin/mail does	not do aliasing, and UUCP usu-
       ally does not read its mail.

       The format of a cron command is very much the V7	standard, with a  num-
       ber  of upward-compatible extensions.  Each line	has five time and date
       fields, followed	by a user name (with optional ``:<group>'' and ``/<lo-
       gin-class>'' suffixes) if this is the system crontab file, followed  by
       a command.  Commands are	executed by cron(8) when the minute, hour, and
       month  of  year fields match the	current	time, and when at least	one of
       the two day fields (day of month, or day	of week) matches  the  current
       time  (see  ``Note''  below).  cron(8) examines cron entries once every
       minute.	The time and date fields are:

	     field	   allowed values
	     -----	   --------------
	     minute	   0-59
	     hour	   0-23
	     day of month  1-31
	     month	   1-12	(or names, see below)
	     day of week   0-7 (0 or 7 is Sun, or use names)

       A field may be an asterisk (*), which always stands for ``first-last''.

       Ranges of numbers are allowed.  Ranges are two numbers separated	with a
       hyphen.	The specified range is inclusive.  For example,	 8-11  for  an
       ``hours'' entry specifies execution at hours 8, 9, 10 and 11.

       Lists are allowed.  A list is a set of numbers (or ranges) separated by
       commas.	Examples: ``1,2,5,9'', ``0-4,8-12''.

       Step  values can	be used	in conjunction with ranges.  Following a range
       with ``/<number>'' specifies skips of the number's  value  through  the
       range.  For example, ``0-23/2'' can be used in the hours	field to spec-
       ify command execution every other hour (the alternative in the V7 stan-
       dard  is	``0,2,4,6,8,10,12,14,16,18,20,22'').  Steps are	also permitted
       after an	asterisk, so if	you want to say	``every	two hours'', just  use
       ``*/2''.

       Names  can  also	 be used for the ``month'' and ``day of	week'' fields.
       Use the first three letters of the particular day or month  (case  does
       not matter).  Ranges and	lists are also allowed.

       The  ``sixth'' field (the rest of the line) specifies the command to be
       run.  One or more command options may precede  the  command  to	modify
       processing  behavior.   The entire command portion of the line, up to a
       newline or % character, will be executed	by /bin/sh  or	by  the	 shell
       specified  in the SHELL variable	of the cronfile.  Percent-signs	(%) in
       the command, unless escaped with	backslash (\), will  be	 changed  into
       newline	characters, and	all data after the first % will	be sent	to the
       command as standard input.

       The following command options can be supplied:

       -n      No mail is sent after a successful run.	The  execution	output
	       will  only  be mailed if	the command exits with a non-zero exit
	       code.  The -n option is an attempt to cure potentially  copious
	       volumes of mail coming from cron(8).

       -q      Execution will not be logged.

       Duplicate options are not allowed.

       Note:  The  day of a command's execution	can be specified by two	fields
       -- day of month,	and day	of week.  If both fields are  restricted  (ie,
       are  not	*), the	command	will be	run when either	field matches the cur-
       rent time.  For example,	``30 4 1,15 * 5'' would	cause a	command	to  be
       run at 4:30 am on the 1st and 15th of each month, plus every Friday.

       Instead of the first five fields, a line	may start with `@' symbol fol-
       lowed  either  by  one  of eight	special	strings	or by a	numeric	value.
       The recognized special strings are:

	     string	     meaning
	     ------	     -------
	     @reboot	     Run once, at startup of cron.
	     @yearly	     Run once a	year, "0 0 1 1 *".
	     @annually	     (same as @yearly)
	     @monthly	     Run once a	month, "0 0 1 *	*".
	     @weekly	     Run once a	week, "0 0 * * 0".
	     @daily	     Run once a	day, "0	0 * * *".
	     @midnight	     (same as @daily)
	     @hourly	     Run once an hour, "0 * * *	*".
	     @every_minute   Run once a	minute,	"*/1 * * * *".
	     @every_second   Run once a	second.

       The `@' symbol followed by a numeric value has a	special	notion of run-
       ning a job that many seconds after completion of	the  previous  invoca-
       tion  of	 the job.  Unlike regular syntax, it guarantees	not to overlap
       two or more invocations of the same job during normal  cron  execution.
       Note,  however,	that  overlap may occur	if the job is running when the
       file containing the job is modified  and	 subsequently  reloaded.   The
       first  run  is scheduled	for the	specified number of seconds after cron
       is started or the crontab entry is reloaded.

EXAMPLE	CRON FILE
       # use /bin/sh to	run commands, overriding the default set by cron
       SHELL=/bin/sh
       # mail any output to `paul', no matter whose crontab this is
       MAILTO=paul
       #
       # run five minutes after	midnight, every	day
       5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
       # run at	2:15pm on the first of every month -- output mailed to paul
       15 14 1 * *     $HOME/bin/monthly
       # run at	10 pm on weekdays, annoy Joe
       0 22 * *	1-5    mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
       23 0-23/2 * * * echo "run 23 minutes after midn,	2am, 4am ..., everyday"
       5 4 * * sun     echo "run at 5 after 4 every sunday"
       # run at	5 minutes intervals, no	matter how long	it takes
       @300	       svnlite up /usr/src
       # run every minute, suppress logging
       * * * * *       -q date
       # run every minute, only	send mail if ping fails
       * * * * *       -n ping -c 1 freebsd.org

SEE ALSO
       crontab(1), cron(8)

EXTENSIONS
       When specifying day of week, both day 0 and day 7  will	be  considered
       Sunday.	BSD and	ATT seem to disagree about this.

       Lists  and ranges are allowed to	co-exist in the	same field.  "1-3,7-9"
       would be	rejected by ATT	or BSD cron --	they  want  to	see  "1-3"  or
       "7,8,9" ONLY.

       Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".

       Names of	months or days of the week can be specified by name.

       Environment  variables  can  be set in the crontab.  In BSD or ATT, the
       environment handed  to  child  processes	 is  basically	the  one  from
       /etc/rc.

       Command output is mailed	to the crontab owner (BSD cannot do this), can
       be  mailed  to  a  person  other	than the crontab owner (SysV cannot do
       this), or the feature can be turned off and no mail will	be sent	at all
       (SysV cannot do this either).

       All of the `@' directives that can appear in place of  the  first  five
       fields are extensions.

       Command processing can be modified using	command	options.  The `-q' op-
       tion  suppresses	 logging.  The `-n' option does	not mail on successful
       run.

AUTHORS
       Paul Vixie <paul@vix.com>

BUGS
       If you are in one of the	70-odd countries that observe Daylight Savings
       Time, jobs scheduled during the rollback	or advance may be affected  if
       cron(8)	is not started with the	-s flag.  In general, it is not	a good
       idea to schedule	jobs during this period	if cron(8) is not started with
       the -s flag, which is enabled by	default.  See  cron(8)	for  more  de-
       tails.

       For  US	timezones (except parts	of AZ and HI) the time shift occurs at
       2AM local time.	For others, the	output of the zdump(8) program's  ver-
       bose (-v) option	can be used to determine the moment of time shift.

FreeBSD	13.2			March 29, 2020			    CRONTAB(5)

NAME | DESCRIPTION | EXAMPLE CRON FILE | SEE ALSO | EXTENSIONS | AUTHORS | BUGS

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