Index for Section 8

Alphabetical listing for C

cron(8)
NAME
  cron - The system clock daemon

SYNOPSIS
  /usr/sbin/cron

DESCRIPTION
  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 file.

  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 executes a sync system call (approximately once a minute)
  to ensure that all information in memory that should be on disk (buffered
  output) is written out.  These periodic updates minimize the possibility of
  file system damage in the event of a crash.  The cron command creates a log
  of its activities.  The cron daemon must be started from the system startup
  scripts because it must begin execution without a login user ID set.	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

  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

    ·  Kernel authorizations

DIAGNOSTICS
  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
  /usr/sbin/cron
	    Specifies the command path.


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

  Functions:  sync(2)