crontab(1)               USER COMMANDS                 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. If
     the VISUAL shell variable is set, it will be used instead of
     the  EDITOR  variable.  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 /usr/sbin/cron.d/cron.allow.  If that file does not
     exist, the file  /usr/sbin/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



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crontab(1)               USER COMMANDS                 crontab(1)



     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 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 stan-
     dard 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
     /usr/sbin/cron.d/logaccounting information
     /usr/sbin/cron.d/cron.allowlist of allowed users
     /usr/sbin/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.

     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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