cron(1M)                   C2 Trusted DG/UX 5.4.2T                  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; crontab files are submitted via the crontab
       command.  You may also schedule commands which are to be executed
       only once via the at command.  Only a single cron process may be
       running at any one time.

       NOTE:  You must have permission to create crontab files.

       In C2 Trusted DG/UX, cron is a service initiator which must set the
       authentication ID (authid) for all cron sessions it starts.  In order
       to do this, cron must be running with its authid equal to zero.  The
       only way to accomplish this is to have cron be started by init (see
       rc.init(1M)), or by some other mechanism started from init.

       To keep a log of all actions taken by cron, CRONLOG=YES (by default)
       must be specified in the /etc/default/cron file.  If CRONLOG=NO is
       specified, no logging is done.  Keeping the log is a user
       configurable option since cron can potentially create huge log files.

       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 factorthe 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.



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cron(1M)                   C2 Trusted DG/UX 5.4.2T                  cron(1M)


       On a Trusted DG/UX system, cron jobs are run with the authentication
       identifier (AUTHID) equal to the originator's AUTHID and a MAC label
       of the submitting process.  The audit mask is CRON_DEFAULT, which
       must always be defined in /etc/tcb/auditaliasdefs.  A value for
       CRON_DEFAULT is supplied with the system, but it may be changed as
       long as it is always a valid mask.

FILES
       /etc/cron.d            main cron directory
       /etc/cron.d/queuedefs  scheduling information
       /var/cron/log          accounting information (log file)
       /var/spool/cron        spool area
       /etc/default/cron      defaults file
       /var/spool/cron/atjobs directory containing jobs submitted through at
       /var/spool/cron/crontabs
                              directory containing jobs submitted through
                              crontab

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

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

NOTES
       Cron(1M) examines crontab files (located in /var/spool/cron/crontabs)
       and at command files (located in /var/spool/cron/atjobs) only during
       process initialization and when a file changes.  This reduces the
       overhead of checking for new or changed files.  On a Trusted DG/UX
       system, these two directories are both multilevel directories.  This
       allows users to have concurrent cron jobs at any level they are
       authorized to submit cron jobs at.

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)                         2