cron(1M)                                                    cron(1M)


       NAME
             cron - clock daemon

       SYNOPSIS
             /usr/sbin/cron [nofork]

       DESCRIPTION
             The cron command starts a process that executes commands at
             specified dates and times.  Regularly scheduled commands can
             be specified according to instructions found in crontab files
             in the directory /var/spool/cron/crontabs.  Users can submit
             their own crontab file via the crontab command.  Commands to
             be executed only once may be submitted via the at command.

             cron normally forks itself and places itself into the
             background.  When the nofork option is specified, this initial
             fork is not performed. This would allow cron to be started via
             inittab rather than during system boot time.

             The commands are not executed if, at the time of execution,
             the requesting user ID or level ID has been deleted, or if the
             level is no longer a valid login level for the requesting
             user.

             cron only examines crontab files and at command files during
             process initialization and when a file changes via the crontab
             or at commands.  This reduces the overhead of checking for new
             or changed files at regularly scheduled intervals.

             Because cron never exits, it should be executed only once,
             normally through /etc/rc2.d/S75cron at system boot time.  The
             file /etc/cron.d/LCK_CRON is used as a lock file to prevent
             the execution of more than one cron.

             Use the following files, described in cron(4), to control
             cron:

                   To specify whether cron is to log all actions, set
                   CRONLOG to YES or to NO in /etc/default/cron.  cron
                   usually creates huge log files.

                   Specify the number of concurrent jobs per user, their
                   priority, and a retry interval in the file
                   /etc/cron.d/queuedefs.




                           Copyright 1994 Novell, Inc.               Page 1

      cron(1M)                                                    cron(1M)


      NOTE
            Changing the time of day clock on the system affects the
            execution of jobs specified in crontab files.  If the clock is
            moved ahead, the jobs scheduled for the skipped time interval
            will not be run.  If the clock is moved back, the jobs already
            executed in the time interval to be revisited will be run a
            second time.  Adjusting the system time because of standard or
            alternate time zone changes, including daylight time changes,
            causes this problem.

      FILES
            /etc/cron.d                   main cron directory
            /etc/cron.d/queuedefs         concurrency, priority, retry
                                          options file
            /etc/cron.d/LCK_CRON          lock file
            /etc/default/cron             log options file
            /var/cron/log                 accounting information
            /var/spool/cron               spool area
            /usr/lib/locale/locale/LC_MESSAGES/uxcore
                                          language-specific message file
                                          [See LANG on environ(5).]

      REFERENCES
            at(1), cron(4), crontab(1)

      DIAGNOSTICS
            A history of all actions taken by cron is recorded in
            /var/cron/log if logging is turned on.




















                          Copyright 1994 Novell, Inc.               Page 2