cron(1m)                   DG/UX 4.30                    cron(1m)



     NAME
          cron - clock agent

     SYNOPSIS
          /etc/cron

     DESCRIPTION
          Cron executes commands at specified dates and times.  You
          can schedule commands on a regular basis according to
          instructions found in crontab files.

          NOTE:
               You must have permission to create crontab files.

          Commands that are to be executed only once may be submitted
          via the command.  Because cron never exits, it should be
          executed only once.  This is best done by running cron from
          the initialization process through the rc script mechanism.
          (see rc.init(1m)).

          You can change the way cron schedules jobs by changing
          entries in the queuedefs file.  The file has two lines, one
          for the at queue (a.) and one for the batch queue (b.):

               a.XjYnZw
               b.XjYnZw

          where:

          X    is the maximum number of jobs allowed to execute
               simultaneously.  This cannot be set higher than 25.

          Y    is the nice factor--the job priority number will be
               raised by this amount.  The higher the number, the less
               attention the job gets from the CPU.  The maximum nice
               factor is 20.

          Z    is how long to wait, in seconds, before trying to
               reschedule a queue request when the job queue is full.

          The default limits are set to work as follows:

               a.4j1n
               b.2j2n90w

          If you increase the job limits, be on guard for a potential
          impact on system performance, especially on smaller machines
          or machines having lots of active users.

     FILES
          /var/spool/cron       main cron directory
          /var/spool/cron/log   accounting information



     Licensed material--property of copyright holder(s)         Page 1

     cron(1m)                   DG/UX 4.30                    cron(1m)



          /var/spool/cron/queuedefs
                                scheduling information
          /var/spool/cron       spool area
          /usr/bin/crontab      cron instruction file

     NOTES
          Cron(1m) examines crontab files (located in /var/spool/cron)
          and at command files only during process initialization and
          when a file changes.  This reduces the overhead of checking
          for new or changed files.  You can submit your own crontab
          file via the crontab command.

     SEE ALSO
          at(1), crontab(1), init(1m), sh(1).

     DIAGNOSTICS
          A history of all actions taken by cron are recorded in
          /var/spool/cron/log.

     BUGS
          When it runs out of jobs to do, cron(1m) tries to redo jobs
          it has already done.  This behavior is potentially
          dangerous, so you should always keep it busy, preferably
          with something like uuclean or a dummy job.  This bug
          originated in AT&T System V.






























     Licensed material--property of copyright holder(s)         Page 2