jjeong

CRONTAB(1)							    CRONTAB(1)

NAME
       crontab - maintain crontab files for individual users (V3)

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

DESCRIPTION
       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 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 con-
       figuration parameters, only the super user will be allowed to use  this
       command,  or  all  users will be able to use this command. 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 tweaked.  If this option is not given, crontab exam-
       ines "your" crontab, i.e., the crontab of the person executing the com-
       mand.   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
       given.

       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  automati-
       cally.  If  neither  of	the environment variables is defined, then the
       default editor /usr/bin/editor is used.

DEBIAN SPECIFIC
       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
       sequence

       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  vari-
       able  CRONTAB_NOHEADER  to 'N', which will cause the crontab -l command
       to emit the extraneous header.

SEE ALSO
       crontab(5), cron(8)

FILES
       /etc/cron.allow
       /etc/cron.deny

STANDARDS
       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.

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

BUGS
       Although  cron  requires  that each entry in a crontab end in a newline
       character, the neither the crontab command nor  the  cron  daemon  will
       detect this error. Instead, the crontab will appear load normally. How-
       ever, the command will never run. The best choice  is  to  ensure  that
       your crontab has a blank line at the end.

AUTHOR
       Paul Vixie <paul@vix.com>

4th Berkeley Distribution      29 December 1993 		    CRONTAB(1)