crontab(1)         UNIX System V(User Environment Utilities)         crontab(1)


NAME
      crontab - user crontab file

SYNOPSIS
      crontab [file]
      crontab -e [ -u username ]
      crontab -r [ -u username ]
      crontab -l [ -u 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 -u 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 -e option invokes the editor specified by the VISUAL environment
      variable, and if that is null, it looks at the EDITOR environment
      variable, and if that is null, it invokes ed [see ed(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
      use -u username following the -r or -l options to remove or list the
      crontab file of the specified user.

      Note, the -u before the username only needs to be specified on Intel
      processor based computers.  Others can specify username without the -u.

      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


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crontab(1)         UNIX System V(User Environment Utilities)         crontab(1)


      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).

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

NOTES
      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.

      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.

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












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