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CRONTAB(5)							    CRONTAB(5)

       crontab - tables for driving cron

       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 hash-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

       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 value string is
       not parsed for environmental substitutions, thus lines like

	   PATH = $HOME/bin:$PATH

       will not work as you might expect.

       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   crontabs	owner.	 PATH	is   set   to
       "/usr/bin:/bin".   HOME,  SHELL, and PATH may be overridden by settings
       in the crontab; LOGNAME is the user that the job is running  from,  and
       may not be changed.

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

       In addition to LOGNAME, HOME, and SHELL, cron(8) will look at MAILTO if
       it  has	any  reason  to  send  mail as a result of running commands in
       this crontab.  If MAILTO is defined (and non-empty), mail  is  sent
       to  the	user so named.	If MAILTO is defined but empty (MAILTO=""), no
       mail will be sent.  Otherwise mail is sent to the owner of the crontab.

       On  the	Debian GNU/Linux system, cron supports the pam_env module, and
       loads the environment specified	by  /etc/security/pam_env.conf.   How
       ever,  the PAM setting do NOT override the settings described above nor
       any settings in the crontab file itself. Note in particular that if you
       want  a PATH other than "/usr/bin:/bin", you will need to set it in the
       crontab file.

       By default, cron will send mail using the mail  "Content-Type:"	header
       of  "text/plain"  with  the  "charset="	parameter set to the charmap /
       codeset of the locale in which crond(8) is started up - ie. either  the
       default system locale, if no LC_* environment variables are set, or the
       locale specified by the LC_* environment variables  (  see  locale(7)).
       You can use different character encodings for mailed cron job output by
       setting the CONTENT_TYPE  and  CONTENT_TRANSFER_ENCODING  variables  in
       crontabs, to the correct values of the mail headers of those names

       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 command, followed by a newline character (\n).
       The system crontab (/etc/crontab) uses the same format, except that the
       username  for  the  command is specified after the time and date fields
       and before the command. The fields may be separated by spaces or  tabs.

       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) match 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 / specifies skips of the numbers  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

       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
       doesnt matter).	Ranges or lists of names are not allowed.

       The  sixth field (the rest of the line) specifies the command to be
       run.  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 crontab file.  Percent-signs (%) in the  command,
       unless escaped with backslash (\), will be changed into newline charac
       ters, and all data after the first % will be sent  to  the  command  as
       standard  input.  There	is  no way to split a single command line onto
       multiple lines, like the shells trailing "\".

       Note: The day of a commands execution can be specified by two fields
       day  of	month,	and day of week.  If both fields are restricted (i.e.,
       arent *), 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, one  of  eight  special  strings  may

	      string	     meaning
	      ------	     -------
	      @reboot	     Run once, at startup.
	      @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 * * * *".

       # use /bin/bash to run commands, instead of the default /bin/sh
       # mail any output to paul, no matter whose crontab this is
       # 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 "Its 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"

       This has the username field, as used by /etc/crontab.
       # /etc/crontab: system-wide crontab
       # Unlike any other crontab you dont have to run the crontab
       # command to install the new version when you edit this file
       # and files in /etc/cron.d. These files also have username fields,
       # that none of other the crontabs do.


       # m h dom mon dow user	 command
       42 6 * * *	 root	 run-parts --report /etc/cron.daily
       47 6 * * 7	 root	 run-parts --report /etc/cron.weekly
       52 6 1 * *	 root	 run-parts --report /etc/cron.monthly
       # Removed invocation of anacron, as this is now handled by a
       # /etc/cron.d file

       cron(8), crontab(1)

       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".

       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

       Command output is mailed to the crontab owner (BSD cant do this),  can
       be  mailed  to  a  person  other  than the crontab owner (SysV cant do
       this), or the feature can be turned off and no mail will be sent at all
       (SysV cant do this either).

       All  of	the  @	commands  that can appear in place of the first five
       fields are extensions.

       Paul Vixie 

4th Berkeley Distribution	24 January 1994 		    CRONTAB(5)

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