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Start program in background (or start crontab ahead of time)
07-21-2009
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CRONTAB(1) BSD General Commands Manual CRONTAB(1) NAME
crontab -- maintain crontab files for individual users (V3) SYNOPSIS
crontab [-u user] file crontab [-u user] { -l | -r | -e } DESCRIPTION
The crontab utility is the program used to install, deinstall or list the tables used to drive the cron(8) daemon in Vixie Cron. Each user can have their own crontab, and they are not intended to be edited directly. (Darwin note: Although cron(8) and crontab(5) are officially supported under Darwin, their functionality has been absorbed into launchd(8), which provides a more flexible way of automatically executing commands. See launchctl(1) for more information.) If the /usr/lib/cron/cron.allow file exists, then you must be listed therein in order to be allowed to use this command. If the /usr/lib/cron/cron.allow file does not exist but the /usr/lib/cron/cron.deny file does exist, then you must not be listed in the /usr/lib/cron/cron.deny file in order to use this command. If neither of these files exists, then depending on site-dependent configuration parameters, only the super user will be allowed to use this command, or all users will be able to use this command. The format of these files is one username per line, with no leading or trailing whitespace. Lines of other formats will be ignored, and so can be used for com- ments. 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. The following options are available: -u Specify 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(1) can confuse crontab and that if you are running inside of su(1) you should always use the -u option for safety's sake. -l Display the current crontab on standard output. -r Remove the current crontab. -e Edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables. The specified editor must edit the file in place; any editor that unlinks the file and recreates it cannot be used. After you exit from the editor, the modified crontab will be installed automatically. FILES
/usr/lib/cron/cron.allow /usr/lib/cron/cron.deny DIAGNOSTICS
A fairly informative usage message appears if you run it with a bad command line. SEE ALSO
crontab(5), compat(5), cron(8), launchctl(1) STANDARDS
The crontab command conforms to IEEE Std 1003.2 (``POSIX.2''). The new command syntax differs from previous versions of Vixie Cron, as well as from the classic SVR3 syntax. AUTHORS
Paul Vixie <paul@vix.com> BSD
December 29, 1993 BSD