cron(1M)																  cron(1M)

NAME

       cron - timed-job execution daemon

SYNOPSIS

DESCRIPTION

       executes  commands  at specified dates and times.  Regularly scheduled commands can be specified according to instructions placed in files.
       Users can submit their own files with a command (see crontab(1)).  Users can submit commands that are to be executed only once with  an	or
       command.

       Since  never  exits, it should be executed only once.  This is best done by running from the initialization process with the startup script
       (see init(1M)).

       only establishes a schedule for files and or command files during process initialization and when it is notified by or that a file has been
       added, deleted, or modified.

       When executes a job, the job's user and group IDs are set to those of the user who submitted the job.

   Spring and Autumn Time Transitions
       On  the days of daylight savings (summer) time transition (in time zones and countries where daylight savings time applies), schedules com-
       mands differently from normal.

       In the following description, an ambiguous time refers to an hour and minute that occurs twice in the same day because of a  daylight  sav-
       ings  time  transition  (usually  on  a day during the Autumn season).  A nonexistent time refers to an hour and minute that does not occur
       because of a daylight savings time transition (usually on a day during the Spring season).  DST-shift refers to the offset that is  applied
       to  standard  time to result in daylight savings time.  This is normally one hour, but can be any combination of hours and minutes up to 23
       hours and 59 minutes (see tztab(4)).

       When a command is specified to run at an ambiguous time, the command is executed only once at the occurrence of the ambiguous time.

       When a command is specified to run at a nonexistent time, the command is executed after the specified time by an amount of  time  equal	to
       the  DST-shift.	When such an adjustment would conflict with another time specified to run the command, the command is run only once rather
       than running the command twice at the same time.

       Commands that are scheduled to run during all hours (there is a is in the hour field of the entry) are scheduled without any adjustment.

EXTERNAL INFLUENCES

   Environment Variables
       determines the language in which messages are displayed.

       If is not specified or is set to the empty string, it defaults to "C" (see lang(5)).  If  any  internationalization  variable  contains	an
       invalid setting, all internationalization variables default to "C" (see environ(5)).

DIAGNOSTICS

       A history of all actions taken by is recorded in

EXAMPLES

       The  following  examples assume that the time zone is In this time zone, the DST transition occurs one second before 2:00 a.m. and the DST-
       shift is 1 hour.

       Consider the following entries in a file:

       For the period of 1:00 a.m. to 4:00 a.m. on the days of DST transition, the results will be:

						  Job	       Times Run in Fall   Times Run in Spring
						  -----------------------------------------------------
						  Job_1 	   01:00 MDT		01:00 MST
						  Job_2 	   02:00 MDT		03:00 MDT
						  Job_3 	   03:00 MST		03:00 MDT
						  Job_4 	   04:00 MST		04:00 MDT
						  Job_hourly	   01:00 MDT		01:00 MST
								   02:00 MDT
								   02:00 MST
								   03:00 MST		03:00 MDT
								   04:00 MST		04:00 MDT
						  Multiple_1	   02:00 MDT
								   03:00 MST		03:00 MDT
								   04:00 MST		04:00 MDT
						  Multiple_2	   02:00 MDT		03:00 MDT
								   04:00 MST		04:00 MDT

WARNINGS

       In the Spring, when there is a nonexistent hour because of daylight savings time, a command that is scheduled to run multiple times  during
       the  nonexistent  hour will only be run once.  For example, a command scheduled to run at 2:00 and 2:30 a.m. in the time zone will only run
       at 3:00 a.m.  The command that was scheduled at 2:30 a.m. will not be run at all, instead of running at 3:30 a.m.

DEPENDENCIES

   HP Process Resource Manager
       If the optional HP Process Resource Management (PRM) software is installed and  configured,  jobs  are  launched  in  the  initial  process
       resource group of the user that scheduled the job.  The user's initial group is determined at the time the job is started, not when the job
       is scheduled.  If the user's initial group is not defined, the job runs in the user default group See prmconfig(1) for a description of how
       to configure HP PRM, and prmconf(4) for a description of how the user's initial process resource group is determined.

AUTHOR

       was developed by AT&T and HP.

FILES

       Main			     directory

       Directory containing	     and job files

       Directory containing	     files

       Accounting information

SEE ALSO

       at(1), crontab(1), sh(1), init(1M), queuedefs(4), tztab(4).

       HP Process Resource Manager: prmconfig(1), prmconf(4) in

STANDARDS CONFORMANCE

																	  cron(1M)