INIT(8)                 COMMAND REFERENCE                 INIT(8)



NAME
     init - process control initialization

SYNOPSIS
     /etc/init

DESCRIPTION
     Init is invoked inside UTek as the last step in the boot
     procedure.  It normally then runs the automatic reboot
     sequence as described in reboot(8), and if this succeeds,
     begins multi-user operation.  If the reboot fails, it
     commences single-user operation by giving the super-user a
     shell on the console.

     It is possible to pass parameters from the boot program to
     init so that single-user operation is commenced immediately.
     For the 6200 series, the parameter S will cause this.  The
     parameter M will cause multi-user operation to begin after
     reboot, as described above.

     When such single user operation is terminated by killing the
     single-user shell (i.e. by hitting ^D), init runs /etc/rc
     without the reboot parameter.  This command file performs
     housekeeping operations such as removing temporary files,
     mounting file systems, and starting daemons.

     In multi-user operation, init's role is to create a process
     for each terminal port on which a user may log in.  To begin
     such operations, it reads the file /etc/ttys and forks
     several times to create a process for each terminal
     specified in the file.  Each of these processes opens the
     appropriate terminal for reading and writing.  These
     channels thus receive file descriptors 0, 1 and 2, the
     standard input and output and the diagnostic output.
     Opening the terminal will usually involve a delay, since the
     open is not completed until someone is dialed up and carrier
     established on the channel.  If a terminal exists but an
     error occurs when trying to open the terminal init complains
     by writing a message to the system console; the message is
     repeated every 10 minutes for each such terminal until the
     terminal is shut off in /etc/ttys and init is notified (by a
     hangup signal, as described below), or the terminal becomes
     accessible (init checks again every minute).  After an open
     succeeds, /etc/getty is called with argument as specified by
     the second character of the ttys file line.  Getty reads the
     user's name and invokes login to log in the user and execute
     the Shell.

     Ultimately the Shell will terminate because of an end-of-
     file either typed explicitly or generated as a result of
     hanging up.  The main path of init, which has been waiting
     for such an event, wakes up and removes the appropriate



Printed 10/17/86                                                1

INIT(8)                 COMMAND REFERENCE                 INIT(8)



     entry from the file utmp, which records current users, and
     makes an entry in /usr/adm/wtmp, which maintains a history
     of logins and logouts.  The wtmp entry is made only if a
     user logged in successfully on the line.  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.  The Shell process on each line which used to be
     active in ttys but is no longer there is terminated; a new
     process is created for each added line; lines 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 sending a hangup signal to the init process:
     use `kill -HUP 1.'

     Init will terminate multi-user operations and resume
     single-user mode if sent a terminate (TERM) signal, i.e.
     ``kill -TERM 1''.  If there are processes outstanding which
     are deadlocked (due to hardware or software failure), init
     will not wait for them all to die (which might take
     forever), but 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, i.e. ``kill -TSTP 1''.  A later hangup will resume
     full multi-user operations, or a terminate will initiate a
     single user shell.  This hook is used by reboot(8) and
     halt(8).

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 rc 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 configuration.

     WARNING: Something is hung (won't die); ps -axl advised.



Printed 10/17/86                                                2

INIT(8)                 COMMAND REFERENCE                 INIT(8)



         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), crash(8), getty(8),
     halt(8), rc(8), reboot(8), shutdown(8).















































Printed 10/17/86                                                3

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