Provided by: cron_3.0pl1-120ubuntu3_i386 bug


       crontab - maintain crontab files for individual users (Vixie Cron)


       crontab [ -u user ] file
       crontab [ -u user ] [ -i ] { -e | -l | -r }


       crontab  is  the  program used to install, deinstall or list the tables
       used to drive the cron(8) daemon in Vixie Cron.   Each  user  can  have
       their    own    crontab,    and    though    these    are    files   in
       /var/spool/cron/crontabs, they are not intended to be edited directly.

       If the /etc/cron.allow file exists, then you must be listed  (one  user
       per  line)  therein in order to be allowed to use this command.  If the
       /etc/cron.allow file does not exist but the  /etc/cron.deny  file  does
       exist,  then you must not be listed in the /etc/cron.deny file in order
       to use this command.

       If neither of these files  exists,  then  depending  on  site-dependent
       configuration  parameters,  only  the super user will be allowed to use
       this command, or all users will be able to use this command.

       If both files exist then /etc/cron.allow takes precedence. Which  means
       that  /etc/cron.deny  is not considered and your user must be listed in
       /etc/cron.allow in order to be able to use the crontab.

       Regardless  of  the  existance  of  any  of  these  files,   the   root
       administrative user is always allowed to setup a crontab.  For standard
       Debian systems, all users may use this command.

       If the -u option is given, it specifies the  name  of  the  user  whose
       crontab  is  to  be  used (when listing) or modified (when editing). If
       this option is not given, crontab examines "your"  crontab,  i.e.,  the
       crontab  of  the  person  executing  the  command.  Note that su(8) can
       confuse crontab and that if you are running inside of su(8) you  should
       always use the -u option for safety's sake.

       The  first  form  of this command is used to install a new crontab from
       some named file or standard  input  if  the  pseudo-filename  ``-''  is

       The  -l  option  causes the current crontab to be displayed on standard
       output. See the note under DEBIAN SPECIFIC below.

       The -r option causes the current crontab to be removed.

       The -e option is used to edit the  current  crontab  using  the  editor
       specified  by  the  VISUAL  or EDITOR environment variables.  After you
       exit  from  the  editor,  the  modified  crontab  will   be   installed
       automatically. If neither of the environment variables is defined, then
       the default editor /usr/bin/editor is used.

       The -i option modifies the -r option to prompt the  user  for  a  'y/Y'
       response before actually removing the crontab.


       The  "out-of-the-box"  behaviour for crontab -l is to display the three
       line "DO NOT EDIT THIS FILE" header that is placed at the beginning  of
       the  crontab  when  it  is  installed. The problem is that it makes the

       crontab -l | crontab -

       non-idempotent -- you keep adding copies of  the  header.  This  causes
       pain  to scripts that use sed to edit a crontab. Therefore, the default
       behaviour of the -l option has been changed to not output such  header.
       You  may  obtain  the  original  behaviour  by  setting the environment
       variable CRONTAB_NOHEADER to 'N',  which  will  cause  the  crontab  -l
       command to emit the extraneous header.


       crontab(5), cron(8)



       There    is    one   file   for   each   user's   crontab   under   the
       /var/spool/cron/crontabs directory. Users are not allowed to  edit  the
       files  under  that directory directly to ensure that only users allowed
       by  the  system  to  run  periodic  tasks  can  add  them,   and   only
       syntactically correct crontabs will be written there.  This is enforced
       by having  the  directory  writable  only  by  the  crontab  group  and
       configuring  crontab  command with the setgid bid set for that specific


       The crontab command conforms to IEEE Std1003.2-1992 (``POSIX'').   This
       new  command  syntax  differs  from previous versions of Vixie Cron, as
       well as from the classic SVR3 syntax.


       A fairly informative usage message appears if you run  it  with  a  bad
       command line.

       cron  requires that each entry in a crontab end in a newline character.
       If the last entry in a  crontab  is  missing  the  newline,  cron  will
       consider  the crontab (at least partially) broken and refuse to install


       Paul Vixie <>  is the author of
       and original creator of this manual page. This page has also been modified for
       Debian by Steve Greenland, Javier Fernandez-Sanguino and Christian Kastner.