crontab - maintain crontab files for individual users (ISC Cron V4.1)
crontab [-u user] file
crontab [-u user] [-l | -r | -e] [-i] [-s]
Crontab is the program used to install, deinstall or list the tables
used to drive the cron(8) daemon in ISC Cron. Each user can have their
own crontab, and though these are files in /var/spool/ , they are not
intended to be edited directly. For SELinux in mls mode can be even
more crontabs - for each range. For more see selinux(8).
If the cron.allow file exists, then you must be listed therein in order
to be allowed to use this command. If the cron.allow file does not
exist but the cron.deny file does exist, then you must not be listed in
the cron.deny file in order to use this command. If neither of these
files exists, only the super user will be allowed to use this command.
-u It specifies the name of the user whose crontab is to be
tweaked. 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 given.
-l The current crontab will be displayed on standard output.
-r The current crontab will be removed.
-e This 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
-i This option modifies the -r option to prompt the user for a
'y/Y' response before actually removing the crontab.
-s It will append the current SELinux security context string as an
MLS_LEVEL setting to the crontab file before editing / replace-
ment occurs - see the documentation of MLS_LEVEL in crontab(5).
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 <firstname.lastname@example.org>
4th Berkeley Distribution 15 September 2011 CRONTAB(1)