crontab(1)             (User Environment Utilities)              crontab(1)


   NAME
         crontab - user crontab file

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

   DESCRIPTION
         crontab copies the specified file, or standard input if no file is
         specified, into a directory that holds all users' crontabs.  The -e
         option 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 privileged user.  The environment variable EDITOR determines which
         editor is invoked with the -e option.  The default editor is vi(1).
         The -r option removes a user's crontab from the crontab directory.
         crontab -l will list the crontab file for the invoking user.  Only a
         privileged user can specify a username following the -r or -l options
         to remove or list the crontab file of the specified user.

         Users are permitted to use crontab if their names appear in the file
         /etc/cron.d/cron.allow.  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


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   crontab(1)             (User Environment Utilities)              crontab(1)


         would run a command only on Mondays).

         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 input.

         Any line beginning with a # is a comment and will be ignored.

         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), and
         PATH(=:/bin:/usr/bin:/usr/lbin).

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

   FILES
         /etc/cron.d         main cron directory
         /var/spool/cron/crontabsspool area
         /etc/cron.d/log     accounting information
         /etc/cron.d/cron.allowlist of allowed users
         /etc/cron.d/cron.denylist of denied users

   SEE ALSO
         atq(1), atrm(1), sh(1), su(1), vi(1).
         cron(1M) in the System Administrator's Reference Manual.

   WARNINGS
         If you inadvertently enter the crontab command with no argument(s),
         do not attempt to get out with a CONTROL-D. This will cause all
         entries in your crontab file to be removed.  Instead, exit with a DEL
         (or whatever the interrupt character is ).

         If a privileged user modifies another user's crontab file, resulting
         behavior may be unpredictable.  Instead, the privileged user should
         first su(1M) to the other user's login before making any changes to
         the crontab file."












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