crontab - user crontab file


     crontab [filename]

     crontab [-elr username]


     The crontab utility manages a user's access with  cron  (see
     cron(1M))  by copying, creating, listing, and removing cron-
     tab files. If invoked without options,  crontab  copies  the
     specified  file,  or the standard input if no file is speci-
     fied, into a directory that holds all users' crontabs.

     If crontab is invoked with filename, this will overwrite  an
     existing crontab entry for the user that invokes it.

  crontab Access Control
     Users: Access to crontab is allowed:

        o  if the user's name appears in /etc/cron.d/cron.allow.

        o  if  /etc/cron.d/cron.allow  does  not  exist  and  the
           user's name is not in /etc/cron.d/cron.deny.

     Users: Access to crontab is denied:

        o  if /etc/cron.d/cron.allow exists and the  user's  name
           is not in it.

        o  if /etc/cron.d/cron.allow does not  exist  and  user's
           name is in /etc/cron.d/cron.deny.

        o  if  neither  file  exists,  only  a  user   with   the
  authorization is allowed to submit a

        o  If BSM audit is  enabled,  the  user's  shell  is  not
           audited  and  the  user is not the crontab owner. This
           can occur if the user logs in via a program,  such  as
           some versions of SSH, which does not set audit parame-

     Notice that the rules for allow and deny apply to root  only
     if the allow/deny files exist.

     The allow/deny files consist of one user name per line.

  crontab Entry Format
     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). Notice that the
     specification of days may be made by two fields (day of  the
     month and day of the week). Both are adhered to if specified
     as a list of elements. See EXAMPLES.

     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 NEWLINE character.

     Only the first line (up to a `%' or end of line) of the com-
     mand  field  is  executed by the shell. Other lines are made
     available to the command as standard input. Any  blank  line
     or  line  beginning  with  a  `#'  is  a comment and will be

     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,
     SHELL(=/bin/sh), TZ, and PATH. The  default  PATH  for  user
     cron  jobs  is  /usr/bin;  while  root  cron jobs default to
     /usr/sbin:/usr/bin.  The  default  PATH  can   be   set   in
     /etc/default/cron (see cron(1M)).

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


     The following options are supported:

     -e    Edits a copy of the current user's  crontab  file,  or
           creates  an  empty  file  to  edit if crontab does not
           exist. When editing is complete, the file is installed
           as  the  user's  crontab file. If a username is given,
           the specified user's crontab file  is  edited,  rather
           than the current user's crontab file; this may only be
           done by a user with the  authoriza-
           tion.   The  environment  variable  EDITOR  determines
           which editor  is  invoked  with  the  -e  option.  The
           default  editor is ed(1). Notice that all crontab jobs
           should be submitted using crontab. Do not add jobs  by
           just  editing  the crontab file, because cron will not
           be aware of changes made this way.

           If all lines in the crontab file are deleted, the  old
           crontab  file  will  be  restored.  The correct way to
           delete all lines is to remove the crontab file via the
           -r option.

     -l    Lists the crontab file for the invoking user.  Only  a
           user  with  the  authorization can
           specify a username following the -r or -l  options  to
           remove or list the crontab file of the specified user.

     -r    Removes a user's crontab from the crontab directory.


     Example 1: Cleaning up core files

     This example cleans up core files every weekday  morning  at
     3:15 am:

     15 3 * * 1-5 find $HOME -name core 2>/dev/null | xargs rm -f

     Example 2: Mailing a birthday greeting

     0 12 14 2 * mailx john%Happy Birthday!%Time for lunch.

     Example 3: Specifying days of the month and week

     This 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.


     See environ(5) for descriptions of the following environment
     variables  that  affect  the  execution  of  crontab:  LANG,

           Determine the editor to be invoked when the -e  option
           is specified. The default editor is vi(1).


     The following exit values are returned:

     0     Successful completion.

     >0    An error occurred.


           main cron directory

           list of allowed users

           contains cron default settings

           list of denied users

           accounting information

           spool area for crontab


     See attributes(5) for descriptions of the  following  attri-

    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Availability                | SUNWcsu                     |
    | Interface Stability         | Standard                    |


     atq(1), atrm(1), auths(1), sh(1), vi(1),  cron(1M),  su(1M),
     auth_attr(4), attributes(5), environ(5), standards(5)


     If you inadvertently  enter  the  crontab  command  with  no
     argument(s),  do not attempt to get out with Control-d. This
     removes all entries in your crontab file. Instead, exit with

     If an authorized user modifies another user's crontab  file,
     resulting   behavior  may  be  unpredictable.  Instead,  the
     super-user should first use su(1M) to become  super-user  to
     the  other  user's  login  before  making any changes to the
     crontab file.

     When updating cron, check first for existing crontab entries
     that  may be scheduled close to the time of the update. Such
     entries may be lost if the update  process  completes  after
     the  scheduled  event. This can happen because, when cron is
     notified by crontab to update the internal view of a  user's
     crontab  file, it first removes the user's existing internal
     crontab and any internal scheduled events. Then it reads the
     new  crontab  file  and  rebuilds  the  internal crontab and
     events. This last step takes time, especially with  a  large
     crontab  file,  and  may  complete after an existing crontab
     entry is scheduled to run if it is scheduled  too  close  to
     the  update. To be safe, start a new job at least 60 seconds
     after the current date and time.

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