cron(1M)              UNIX System V(Essential Utilities)               cron(1M)


NAME
      cron - clock daemon

SYNOPSIS
      /usr/sbin/cron

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 which are to be executed only once may be
      submitted via the at command.

      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.

      Since cron never exits, it should be executed only once.  This is done
      routinely through /sbin/rc2.d/S75cron at system boot time.
      /etc/cron.d/FIFO is used as a lock file to prevent the execution of more
      than one cron.

      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 usually creates huge log files.

FILES
     /usr/sbin/cron.d main cron directory

     /etc/default/cron
                       used to maintain a log

     /etc/cron.d/FIFO used as a lock file

     /var/cron/log    accounting information

     /var/spool/cron  spool area

SEE ALSO
      at(1), crontab(1), sh(1) in the User's Reference Manual.

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








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