cron(1M)          MISC. REFERENCE MANUAL PAGES           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.  Com-
     mands  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 cron-
     tab 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.  /usr/lib/cron/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/lib/cron    main cron directory

     /etc/default/cronused to maintain a log

     /usr/lib/cron/FIFO
                      used as a lock file

     /usr/spool/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
     /usr/spool/cron/log.





                Last change: Essential Utilities                1