NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | FILES | STANDARDS | DIAGNOSTICS | AUTHOR | COLOPHON

CRONTAB(1)                      User Commands                     CRONTAB(1)

NAME         top

       crontab - maintains crontab files for individual users

SYNOPSIS         top

       crontab [-u user] file
       crontab [-u user] [-l | -r | -e] [-i] [-s]
       crontab -n [ hostname ]
       crontab -c

DESCRIPTION         top

       Crontab is the program used to install, remove or list the tables
       used to serve 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, you can
       define more crontabs for each range.  For more information, see
       selinux(8).

       In this version of Cron it is possible to use a network-mounted
       shared /var/spool/cron across a cluster of hosts and specify that
       only one of the hosts should run the crontab jobs in the particular
       directory at any one time.  You may also use crontab(1) from any of
       these hosts to edit the same shared set of crontab files, and to set
       and query which host should run the crontab jobs.

       Running cron jobs can be allowed or disallowed for different users.
       For this purpose, use the cron.allow and cron.deny files.  If the
       cron.allow file exists, a user must be listed in it to be allowed to
       use cron If the cron.allow file does not exist but the cron.deny file
       does exist, then a user must not be listed in the cron.deny file in
       order to use cron.  If neither of these files exists, only the super
       user is allowed to use cron.  Another way to restrict access to cron
       is to use PAM authentication in /etc/security/access.conf to set up
       users, which are allowed or disallowed to use crontab or modify
       system cron jobs in the /etc/cron.d/ directory.

       The temporary directory can be set in an environment variable.  If it
       is not set by the user, the /tmp directory is used.

OPTIONS         top

       -u     Appends the name of the user whose crontab is to be modified.
              If this option is not used, crontab examines "your" crontab,
              i.e., the crontab of the person executing the command.  Note
              that su(8) may confuse crontab, thus, when executing commands
              under su(8) you should always use the -u option.  If no
              crontab exists for a particular user, it is created for him
              the first time the crontab -u command is used under his
              username.

       -l     Displays the current crontab on standard output.

       -r     Removes the current crontab.

       -e     Edits 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     Appends 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).

       -n     This option is relevant only if cron(8) was started with the
              -c option, to enable clustering support.  It is used to set
              the host in the cluster which should run the jobs specified in
              the crontab files in the /var/spool/cron directory.  If a
              hostname is supplied, the host whose hostname returned by
              gethostname(2) matches the supplied hostname, will be selected
              to run the selected cron jobs subsequently.  If there is no
              host in the cluster matching the supplied hostname, or you
              explicitly specify an empty hostname, then the selected jobs
              will not be run at all.  If the hostname is omitted, the name
              of the local host returned by gethostname(2) is used.  Using
              this option has no effect on the /etc/crontab file and the
              files in the /etc/cron.d directory, which are always run, and
              considered host-specific.  For more information on clustering
              support, see cron(8).

       -c     This option is only relevant if cron(8) was started with the
              -c option, to enable clustering support.  It is used to query
              which host in the cluster is currently set to run the jobs
              specified in the crontab files in the directory
              /var/spool/cron , as set using the -n option.

SEE ALSO         top

       crontab(5), cron(8)

FILES         top

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

STANDARDS         top

       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         top

       An informative usage message appears if you run a crontab with a
       faulty command defined in it.

AUTHOR         top

       Paul Vixie ⟨vixie@isc.org⟩
       Colin Dean ⟨colin@colin-dean.org⟩

COLOPHON         top

       This page is part of the cronie (crond daemon) project.  Information
       about the project can be found at ⟨https://fedorahosted.org/cronie/⟩.
       If you have a bug report for this manual page, see 
       ⟨https://fedorahosted.org/cronie/⟩.  This page was obtained from the
       project's upstream Git repository
       (http://git.fedorahosted.org/git/cronie.git)on 2014-09-06.  If you
       discover any rendering problems in this HTML version of the page, or
       you believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

cronie                           2012-11-22                       CRONTAB(1)