2.11BSD/man/cat8/cron.0

CRON(8)             UNIX Programmer's Manual              CRON(8)



NAME
     cron - daemon to execute scheduled commands (Vixie Cron)

SYNOPSIS
     cron

DESCRIPTION
     _C_r_o_n should be started from /etc/rc or /etc/rc.local.  It
     will return immediately, so you don't need to start it with
     '&'.

     _C_r_o_n searches /var/cron/tabs for crontab files which are
     named after accounts in /etc/passwd; crontabs found are
     loaded into memory.  _C_r_o_n also searches for /etc/crontab
     which is in a different format (see _c_r_o_n_t_a_b(_5)).  _C_r_o_n then
     wakes up every minute, examining all stored crontabs, check-
     ing each command to see if it should be run in the current
     minute.  When executing commands, any output is mailed to
     the owner of the crontab (or to the user named in the MAILTO
     environment variable in the crontab, if such exists).

     Additionally, _c_r_o_n checks each minute to see if its spool
     directory's modtime (or the modtime on /_e_t_c/_c_r_o_n_t_a_b) has
     changed, and if it has, _c_r_o_n will then examine the modtime
     on all crontabs and reload those which have changed.  Thus
     _c_r_o_n need not be restarted whenever a crontab file is modi-
     fied.  Note that the _C_r_o_n_t_a_b(1) command updates the modtime
     of the spool directory whenever it changes a crontab.

SEE ALSO
     crontab(1), crontab(5)

AUTHOR
     Paul Vixie <paul@vix.com>





















Printed 11/26/99        20 December 1993                        1