INIT (VII) 6/15/72 INIT (VII)





INIT (VII)                   6/15/72                   INIT (VII)





NAME            init  --  process control initialization



SYNOPSIS        /etc/init



DESCRIPTION

        init is invoked inside UNIX as the last step in the boot

        procedure.  Generally its role is to create a process for

        each typewriter on which a user may log in.



        First, init checks to see if the console switches contain

        173030.  (This number is likely to vary between systems.)

        If so, the console typewriter tty is opened for reading

        and writing and the shell is invoked immediately.  This

        feature is used to bring up a test system, or one which

        does not contain DC-11 communications interfaces.  When

        the system is brought up in this way, the getty and login

        routines mentioned below and described elsewhere are not

        needed.



        Otherwise, init does some housekeeping: the mode of each

        DECtape file is changed to 17 (in case the system crashed

        during a tap command); directory /usr is mounted on the

        RK0 disk; directory /sys is mounted on the RK1 disk.

        Also a data-phone daemon is spawned to restart any jobs

        being sent.



        Then init forks several times to create a process for

        each typewriter mentioned in an internal table.  Each of

        these processes opens the appropriate typewriter for

        reading and writing.  These channels thus receive file

        descriptors 0 and 1, the standard input and output.

        Opening the typewriter will usually involve a delay,

        since the open is not completed until someone is dialled

        in (and carrier established) on the channel.  Then the

        process executes the program /etc/getty (q.v.).  getty

        will read the user's name and invoke login (q.v.)  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 ap-

        propriate entry from the file utmp, which records current

        users, and makes an entry in wtmp, which maintains a his-

        tory of logins and logouts.  Then the appropriate type-

        writer is reopened and getty reinvoked.



FILES           /dev/tap?, /dev/tty, /dev/tty?, /tmp/utmp,

                /tmp/wtmp



SEE ALSO        login(I), login(VII), getty(VII), sh(I), dpd(VII)



DIAGNOSTICS     none possible



BUGS            none possible
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