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crontab(1)							   crontab(1)



NAME

  crontab - Submits a schedule of commands to cron

SYNOPSIS

  crontab [file]

  crontab -l  |	-v  | -r  | -e [username]

STANDARDS

  Interfaces documented	on this	reference page conform to industry standards
  as follows:

  crontab:  XCU5.0

  Refer	to the standards(5) reference page for more information	about indus-
  try standards	and associated tags.

OPTIONS

  -e [username]
      Edits a copy of your crontab entry.  If the crontab entry	does not
      exist, creates an	empty entry to edit. The -e option invokes the editor
      specified	by the EDITOR environment variable, or uses /usr/bin/vi	by
      default.	The crontab command installs the new entry when	editing	is
      complete.

      [Tru64 UNIX]  If username	is specified, edits the	file for the speci-
      fied user.  You must have	appropriate privileges to use this option.

  -l  Displays the contents of your crontab file.

  -r  Removes the crontab file from the	crontab	directory.

  -v  [Tru64 UNIX]  Displays the name of your crontab file and the date	and
      time at which you	submitted it with crontab.

OPERANDS

  file
      Path name	of file	that contains crontab specifications in	the format
      described.

DESCRIPTION

  The crontab command copies the specified file	or standard input if you do
  not specify a	file into the /var/spool/cron/crontabs directory, which	holds
  all users' crontab files.

  The cron command runs	commands according to the instructions in the crontab
  files.  The crontab files are	named for users, and the commands in the
  files	are run	under the user's authority.  For example, the commands in the
  /var/spool/cron/crontabs/root	file are run under root	authority.  When you
  use the crontab command, the file under your authority is affected.  For
  example, if adm invokes the crontab -l command, the
  /var/spool/cron/crontabs/adm file is displayed.  If the username argument
  is included, the specified user's crontab file is listed and edited rather
  than the current user's crontab file.	 You must have root privileges to
  specify the username argument.  By default, the vi editor is used.

  Note that the	file /var/spool/cron/crontabs/root contains several entries
  that will run	by default, such as the	following command to back up and
  clean	the /var/adm/wtmp log file:

       0 2 * * 0 /usr/bin/logclean /var/adm/wtmp >> dev/null

  You can configure these default commands to suit your	local system require-
  ments.

  After	cron runs commands according to	the contents of	your crontab file, it
  mails	you the	output from standard output and	standard error for these com-
  mands, unless	you redirect standard output or	standard error.

				     Note

       When entries are	made to	a crontab file by using	the crontab command,
       all previous entries in the file	are removed.

  You can use the crontab command if your user name appears in the
  /usr/lib/cron/cron.allow file.  If that file does not	exist, the crontab
  command checks the /usr/lib/cron/cron.deny file to determine if you should
  be denied access to crontab.	The allow/deny files contain one user name
  per line.  If	neither	file exists, you can submit a job only if you are
  operating with superuser authority.

  Each crontab file entry consists of a	line with six fields, separated	by
  spaces and tabs.  The	information in the fields specifies when the command
  runs and the name of the command.  The fields	specify	the following:

    +  The first field specifies the minute (0 to 59).

    +  The second field	specifies the hour (0 to 23).

    +  The third field specifies the day of the	month (1 to 31).

    +  The fourth field	specifies the month of the year	(1 to 12).

    +  The fifth field specifies the day of the	week (0	to 6 for Sunday	to
       Saturday).

    +  The sixth field specifies the shell command to be executed.

  You can specify the following	values in the fields that indicate the time:

    +  An integer (within the appropriate range	of values)

    +  Two integers separated by a dash	to indicate an inclusive range

    +  A list of integers separated by commas

    +  An asterisk to select all possible values

  You can specify the days on which the	command	is to execute in two fields
  (day of the month and	day of the week).  You can specify both	fields,	or
  you can specify only one field.  To use only one field to specify the	days,
  the other field should contain an asterisk (*).  If both methods are used,
  the command is executed whenever either of the specifications	is met.

  [Tru64 UNIX]	For example, the following entry runs command at midnight on
  the first and	fifteenth days of each month, as well as every Monday:

       0 0 1,15	* 1 command

  The cron program runs	the command named in the sixth field at	the specified
  date and time.  If you include a percent sign	(%) in the sixth field,	cron
  treats everything that precedes it (in that field) as	the command invoca-
  tion,	and makes all that follows it available	to standard input, unless you
  escape the percent sign (\%) or double quote it ("%").  An exclamation
  point	(!) in the sixth field is translated as	a newline character.

  The shell runs only the first	line of	the command field (up to a percent
  sign or End-of-Line).	 All other lines are made available to the command as
  standard input.

  The cron program invokes a subshell from your	$HOME directory.  This means
  that it will not run your .profile file.  If you schedule a command to run
  when you are not logged in and you want to have commands in your .profile
  run, you must	explicitly do so in the	crontab	file.  (For a more detailed
  discussion of	how sh can be invoked, see the sh command.)

  The cron program supplies a default environment for every shell, defining
  HOME,	LOGNAME, SHELL (=/usr/bin/sh), and PATH	(=:/usr/bin).

  [Tru64 UNIX]	To submit commands to the cron daemon, invoke the crontab
  command with the -e option, or perform the following tasks:

   1.  [Tru64 UNIX]  Become the	user that corresponds to the appropriate file
       in the /usr/spool/cron/crontabs directory.  For example,	if you want
       to submit commands that will run	under adm authority, become user adm.

   2.  [Tru64 UNIX]  Use the crontab command with the -l option	to copy	the
       appropriate file	from the /usr/spool/cron/crontabs directory to a tem-
       porary file in your home	directory.  For	example, if you	are user adm,
       you could use the following command:
	    crontab -l >> temp_adm

   3.  [Tru64 UNIX]  Edit the temporary	file and add the commands you want to
       run at a	specified time.

   4.  [Tru64 UNIX]  Use the crontab command and specify the temporary file
       to submit the commands to the cron daemon.

NOTES

   1.  When entries are	made to	a crontab file,	all previous entries are
       erased.

   2.  If your user ID is associated with more than one	user name, crontab
       uses the	first user name	that appears in	the /etc/passwd	file, regard-
       less of which user name you might actually be using.

   3.  [Tru64 UNIX]  The file /usr/lib/cron is a symbolic link to
       /var/adm/cron.

   4.  [Tru64 UNIX]  If	cron.allow exists, the superuser's user	name must
       appear there for	that superuser to be able to use the command.








EXIT STATUS

  The following	exit values are	returned:

  0   Successful completion.

  >>0  An error occurred.

EXAMPLES

   1.  The following example writes the	time to	the console every hour on the
       hour:
	    0 *	* * * echo The hour is `date`. >>/dev/console

   2.  The following example runs calendar at 6:30 a.m.	every Monday, Wednes-
       day, and	Friday:
	    30 6 * * 1,3,5 /usr/bin/calendar -

   3.  The following example writes the	contents of happyholidays.txt to all
       users logged in at 4:00 p.m. each Friday	in December and	each day
       between December	10 and December	31 inclusive:
	    0 16 10-31 12 5 /usr/sbin/wall /var/tmp/happyholidays.txt



ENVIRONMENT VARIABLES

  The following	environment variables affect the execution of crontab:

  EDITOR
      Determines the editor used with the -e option.

  LANG
      Provides a default value for the internationalization variables that
      are unset	or null. If LANG is unset or null, the corresponding value
      from the default locale is used. If any of the internationalization
      variables	contain	an invalid setting, the	utility	behaves	as if none of
      the variables had	been defined.

  LC_ALL
      If set to	a non-empty string value, overrides the	values of all the
      other internationalization variables.

  LC_CTYPE
      Determines the locale for	the interpretation of sequences	of bytes of
      text data	as characters (for example, single-byte	as opposed to multi-
      byte characters in arguments).

  LC_MESSAGES
      Determines the locale for	the format and contents	of diagnostic mes-
      sages written to standard	error.

  NLSPATH
      Determines the location of message catalogues for	the processing of
      LC_MESSAGES.

FILES

  /var/adm/cron
      Main cron	directory.

  /var/spool/cron/crontabs
      Directory	containing the crontab files adm, cronuucp, root, sys,and
      uucp.

  /var/adm/cron/cron.allow
      List of allowed users.

  /var/adm/cron/cron.deny
      List of denied users.

  /var/adm/cron/log
      Log of cron activity.

  /var/adm/cron/queuedefs
      Queue description	file for at, batch, and	cron.

  /etc/passwd
      Contains user information.

  $HOME/.profile
      User profile.

SEE ALSO

  Commands:  at(1), cron(8), mail(1), mailx(1),	Bourne shell sh(1b), POSIX
  shell	sh(1p)

  Files:  queuedefs(4)

  Standards:  standards(5)