CRON(8)                 OpenBSD System Manager's Manual                CRON(8)

NAME
     cron - daemon to execute scheduled commands (Vixie Cron)

SYNOPSIS
     cron

DESCRIPTION
     cron should be started from /etc/rc or /etc/rc.local. It will return im-
     mediately, so you don't need to start it with `&'.

     cron searches its spool directory (/var/cron/tabs) for crontab(5) files
     which are named after accounts in /etc/passwd; crontabs found are loaded
     into memory.  cron also searches for /etc/crontab which is in a different
     format (see crontab(5)). cron then wakes up every minute, examining all
     loaded crontabs, checking each command to see if it should be run in the
     current minute.  When executing commands, any output is mailed to the us-
     er named in the MAILTO environment variable in the crontab, or to the
     owner of the crontab if MAILTO is not present.

     Additionally, cron checks each minute to see if its spool directory's
     modtime (or the modtime on /etc/crontab) has changed, and if it has, cron
     examines the modtime on all crontabs and reloads those which have
     changed.  Thus cron need not be restarted whenever a crontab file is mod-
     ified.  Note that the crontab(1) command updates the modtime of the spool
     directory whenever it changes a crontab.

     Special considerations exist when the clock is changed by less than 3
     hours; for example, at the beginning and end of Daylight Saving Time.  If
     the time has moved forward, those jobs which would have run in the time
     that was skipped will be run soon after the change.  Conversely, if the
     time has moved backward by less than 3 hours, those jobs that fall into
     the repeated time will not be run.

     Only jobs that run at a particular time (not specified as @hourly, nor
     with `*' in the hour or minute specifier) are affected.  Jobs which are
     specified with wildcards are run based on the new time immediately.

     Clock changes of more than 3 hours are considered to be corrections to
     the clock, and the new time is used immediately.

SIGNALS
     On receipt of a SIGHUP, the cron daemon will close and reopen its log
     file.  This is useful in scripts which rotate and age log files.  Natu-
     rally this is not relevant if cron was built to use syslog(3).

SEE ALSO
     crontab(1), crontab(5)

AUTHOR
     Paul Vixie <paul@vix.com>

OpenBSD 2.9                      June 6, 1999                                1
