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crontab - maintain crontab files for individual users (V3)
crontab [ -u user ] file
crontab [ -u user ] [ -l | -r | -e ]
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, they are not
intended to be edited directly.
If the allow file exists, then you must be listed therein in order to
be allowed to use this command. If the allow file does not exist but
the deny file does exist, then you must not be listed in the 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.
The default maximum size for a crontab is 256 kilobytes, but this may
be changed for all users on the system by putting the desired maximum
size (in bytes) in the maxtabsize file.
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(1) can confuse crontab and that if you are running
inside of su(1) 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
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-
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
Paul Vixie <email@example.com>
4th Berkeley Distribution 29 December 1993 CRONTAB(1)