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crontab [-u user] file
crontab [-u user] [-l | -r | -e] [-i] [-s]
Crontab is the program used to install, remove or list the tables used
to drive the cron(8) daemon. 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).
The cron jobs could be allow or disallow for different users. For clas-
sical crontab there exists cron.allow and cron.deny files. If
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. The
second option is using PAM authentication, where you set up users,
which could or couldn't use crontab and also system cron jobs from
The temporary directory could be set in enviroment variables. If it's
not set by user than /tmp is used.
-u Append 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).
Paul Vixie <email@example.com>
Marcela Maslanova 20 July 2009 CRONTAB(1)