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NAME    [Toc]    [Back]

       cron - The system clock daemon

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

       The cron daemon runs shell commands at specified dates and
       times.  Commands that are to run according to a regular or
       periodic schedule are found within the crontab files. Commands
 that are to run once only are found  within  the  at
       files.   You  submit  crontab and at file entries by using
       the crontab and at commands.   Because  the  cron  process
       exits  only when killed or when the system stops, only one
       cron daemon should exist on the system at any given  time.
       Normally, you start the cron daemon from within a run command


       Other   that   logging   a   startup    entry    in    the
       /var/adm/cron/log  file,  the cron daemon does not log its
       activities.  You can use the Event Manager (EVM) to create
       custom  events  for  tasks  that are scheduled by the cron
       daemon. See EVM(5) for more information.

       During process initialization  and  when  cron  detects  a
       change,  it examines the crontab and at files. This strategy
 reduces the overhead of checking for  new  or  changed
       files  at  regularly  scheduled intervals. The cron daemon
       must be started from the system startup scripts because it
       must begin execution without a login user ID set. It maintains
  the  /usr/spool  cron/atjobs  and  the  /usr  spool
       cron/crontabs  spool  direcitories  as multilevel directories;
 jobs and crontabs submitted reside in the  directory
       associated  with the sensitivity level of the process that
       invoked at or crontab. It uses the level of the  subdirectory
  as the one at which to start the job.  The cron communication
 FIFO is graded at the System  High  sensitivity
       level.  The cron daemon starts each job with the following
       process attributes stored with the  job  by  the  invoking
       process:  Login user ID Effective and real user IDs Effective
 and real group IDs Supplementary  groups  Sensitivity
       level Information label

       It  also  establishes  the  following  attributes from the
       authentication profile of the account associated with  the
       login  user  ID of the invoking process: Audit control and
       disposition masks  Clearance  Kernel  authorizations  Base
       privilege set

DIAGNOSTICS    [Toc]    [Back]

       The  at and batch programs will refuse to accept jobs submitted
 from processes whose login  user  ID  is  different
       from the real user ID.

FILES    [Toc]    [Back]

       Specifies the command path.  Main cron directory Directory
       containing the crontab  files.   List  of  allowed  users.
       List  of  denied users This file contains startup information.
 (It  is  not  a  log  of  cron  activities).   Queue
       description file for at, batch, and cron

SEE ALSO    [Toc]    [Back]

       Commands: at(1), crontab(1), rc0(8), rc2(8), rc3(8)

       Files: queuedefs(4)

       Misc: EVM(5)

[ Back ]
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