CRONTAB(1)							   User Commands							CRONTAB(1)

NAME

       crontab - maintains crontab files for individual users

SYNOPSIS

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

DESCRIPTION

       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

       -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

       crontab(5), cron(8)

FILES

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

STANDARDS

       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

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

AUTHOR

       Paul Vixie <vixie@isc.org>
       Colin Dean <colin@colin-dean.org>

cronie								    2012-11-22								CRONTAB(1)