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.
OPTIONS
-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 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 automatically.
-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 / replacement
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.
DIAGNOSTICS
A fairly informative usage message appears if you run it with a bad command
line.
