INIT(8)                 COMMAND REFERENCE                 INIT(8)



NAME
     init - process control initialization

SYNOPSIS
     /etc/init

DESCRIPTION
     init is invoked as the last step in the boot procedure.  It
     normally runs the automatic startup sequence determined by
     the shell script /etc/rc. This command file performs
     housekeeping operations such as removing temporary files,
     mounting file systems, and starting daemons.  If successful,
     init begins multi-user operation, the normal operating mode
     of UTek for multi- and single-user workstations.

     For multi-user operation, init creates a process for each
     terminal or display port a user is logged into.  It forks a
     process for each port specified in the file /etc/ttys.  Each
     of these processes opens the appropriate port for reading
     and writing.  Opening a port may involve a delay on terminal
     ports, since the open may not complete until the terminal is
     fully connected and ready.

     If a terminal exists but an error occurs when trying to open
     it, init complains by writing a message to the system file
     /usr/adm/sulog. The message is repeated every 10 minutes for
     each terminal until it is shut off in /etc/ttys and init is
     notified by a hangup signal, as described here, or the
     terminal becomes accessible (init checks again every
     minute).

     After an open succeeds, init executes the command for that
     port as specified in the file /etc/ttys. This command is
     usually /etc/getty. The command getty reads the user's name
     and invokes the login command to log in the user and execute
     the appropriate shell.

     When the shell terminates because an end-of-file is typed or
     generated as a result of hanging up, init removes the
     appropriate entry from the file utmp that records current
     users. init then makes an entry in /usr/adm/wtmp that
     maintains a history of logins and logouts.  The wtmp entry
     is made only if a user logged in successfully.  Then the
     appropriate terminal is reopened and getty is reinvoked.

     init catches the hangup signal (signal SIGHUP) and
     interprets it to mean that the file /etc/ttys should be read
     again.  For ports that are no longer active, the controlling
     process (shell or getty) is terminated.  For newly active
     ports getty is started.  Ports unchanged in the file are
     undisturbed.  Thus it is possible to drop or add phone lines
     without rebooting the system by changing the ttys file and



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INIT(8)                 COMMAND REFERENCE                 INIT(8)



     sending a hangup signal to the init process. Use:

          kill -HUP 1

     init terminates multi-user operations and resumes single-
     user mode if sent a terminate (TERM) signal (kill -TERM 1).
     If there are processes outstanding that are deadlocked due
     to hardware or software failure, init will not wait for them
     all to die.  It will time out after 30 seconds and print a
     warning message.

     init will cease creating new getty's and allow the system to
     slowly die away if it is sent a terminal stop (TSTP) signal
     (kill -TSTP 1).  A later hangup will resume full multi-user
     operations or a terminate will initiate a single-user shell.
     This facility is used by reboot(8) and halt(8).

     Single-user mode provides the console with a shell with no
     other user-level processes running.  This controls operation
     of the system so that no background cpu or disk activity can
     occur.  It is required for some maintenance activities, such
     as checking active file systems.

     Single-user mode can be entered several ways: Intentionally
     from the boot process or by using the shutdown command with
     no options in multi-user mode.  Also, some failures of
     automatic startup will drop the console into single-user
     mode.

     When single-user operation is terminated by killing the
     single-user shell with a control-D, init runs automatic
     startup.  Since all single-user operations are performed as
     superuser, running in single-user mode is protected by the
     root password regardless of how it is entered.  When the
     single-user shell is terminated with a control-D,
     confirmation is requested so that unwanted multi-user
     activity can't be started inadvertently.

FILES
     /dev/console
     /dev/tty*
     /etc/utmp
     /usr/adm/wtmp
     /etc/ttys
     /etc/rc

DIAGNOSTICS
     init: tty: cannot open.
          A terminal which is turned on in the ttys file cannot
          be opened, usually because the requisite lines are
          either not configured into the system or the associated
          device was not attached during boot-time system



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INIT(8)                 COMMAND REFERENCE                 INIT(8)



          configuration.

     WARNING: Something is hung (won't die); ps -axl advised.
          A process is hung and could not be killed when the
          system was shutting down.  This is usually caused by a
          process which is stuck in a device driver due to a
          persistent device error condition.

SEE ALSO
     kill(1), login(1), sh(1sh), ttys(5), getty(8), halt(8),
     rc(8), reboot(8), shutdown(8)












































Printed 4/7/89                                                  3

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