sac(1M)               UNIX System V(Essential Utilities)                sac(1M)


NAME
      sac - service access controller

SYNOPSIS
      sac -t sanity_interval

DESCRIPTION
      The Service Access Controller (SAC) is the overseer of the server
      machine.  It is started when the server machine enters multiuser mode.
      The SAC performs several important functions as explained below.

      Customizing the SAC environment.  When sac is invoked, it first looks for
      the per-system configuration script /etc/saf/sysconfig.  sac interprets
      sysconfig to customize its own environment.  The modifications made to
      the SAC environment by sysconfig are inherited by all the children of
      the SAC.  This inherited environment may be modified by the children.

      Starting port monitors.  After it has interpreted the sysconfig file,
      the sac reads its administrative file /etc/saf/sactab.  sactab
      specifies which port monitors are to be started.  For each port monitor
      to be started, sac forks a child [fork(2)] and creates a utmp entry with
      the type field set to LOGINPROCESS.  Each child then interprets its
      per-port monitor configuration script /etc/saf/pmtag/config, if the file
      exists.  These modifications to the environment affect the port monitor
      and will be inherited by all its children.  Finally, the child process
      execs the port monitor, using the command found in the sactab entry.
      (See sacadm; this is the command given with the -c option when the port
      monitor is added to the system.)

      Polling port monitors to detect failure.  The -t option sets the
      frequency with which sac polls the port monitors on the system.  This
      time may also be thought of as half of the maximum latency required to
      detect that a port monitor has failed and that recovery action is
      necessary.

      Administrative functions.  The Service Access Controller represents the
      administrative point of control for port monitors.  Its administrative
      tasks are explained below.
      When queried (sacadm with either -l or -L), the Service Access Controller
      returns the status of the port monitors specified, which sacadm prints on
      the standard output.  A port monitor may be in one of six states:

      ENABLED   The port monitor is currently running and is accepting
                connections.  See sacadm(1M) with the -e option.

      DISABLED  The port monitor is currently running and is not accepting
                connections.  See sacadm with the -d option, and see
                NOTRUNNING, below.

      STARTING  The port monitor is in the process of starting up.  STARTING is
                an intermediate state on the way to ENABLED or DISABLED.



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sac(1M)               UNIX System V(Essential Utilities)                sac(1M)


      FAILED    The port monitor was unable to start and remain running.

      STOPPING  The port monitor has been manually terminated but has not
                completed its shutdown procedure.  STOPPING is an intermediate
                state on the way to NOTRUNNING.

      NOTRUNNING
                The port monitor is not currently running.  (See sacadm with
                -k.)  This is the normal ``not running'' state.  When a port
                monitor is killed, all ports it was monitoring are
                inaccessible. It is not possible for an external user to tell
                whether a port is not being monitored or the system is down.
                If the port monitor is not killed but is in the DISABLED state,
                it may be possible (depending on the port monitor being used)
                to write a message on the inaccessible port telling the user
                who is trying to access the port that it is disabled.  This is
                the advantage of having a DISABLED state as well as the
                NOTRUNNING state.

      When a port monitor terminates, the SAC removes the utmp entry for that
      port monitor.

      The SAC receives all requests to enable, disable, start, or stop port
      monitors and takes the appropriate action.

      The SAC is responsible for restarting port monitors that terminate.
      Whether or not the SAC will restart a given port monitor depends on two
      things:

            -  the restart count specified for the port monitor when the port
               monitor was added by sacadm; this information is included in
               /etc/saf/pmtag/sactab

            -  the number of times the port monitor has already been restarted

SEE ALSO
      sacadm(1M), pmadm(1M).

FILES
      /etc/saf/sactab
      /etc/saf/sysconfig
      /var/adm/utmp
      /var/saf/log











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