12/11/72 GETTY (VII)





12/11/72                                              GETTY (VII)





NAME            getty  -- set typewriter mode and get user's name



SYNOPSIS        /etc/getty



DESCRIPTION

        getty is invoked by init (VII) immediately after a type-

        writer is opened following a dial-in.  The user's login

        name is read and the login(I) command is called with this

        name as an argument.  While reading this name getty at-

        tempts to adapt the system to the speed and type of ter-

        minal being used.



        getty initially sets the speed of the interface to 150

        baud, specifies that raw mode is to be used (break on ev-

        ery character), that echo is to be suppressed, and either

        parity allowed.  It types the "login:" message (which in-

        cludes the characters which put the 37 Teletype terminal

        into full-duplex and unlock its keyboard).  Then the

        user's name is read, a character at a time.  If a null

        character is received, it is assumed to be the result of

        the user pushing the "break" ("interrupt") key.  The

        speed is then changed to 300 baud and the "login:" is

        typed again, this time with the appropriate sequence

        which puts a GE TermiNet 300 into full-duplex.  This se-

        quence is acceptable to other 300 baud terminals also.

        If a subsequent null character is received, the speed is

        changed again.  The general approach is to cycle through

        a set of speeds in response to null characters caused by

        breaks.  The sequence at this installation is 150, 300,

        and 134.5 baud.



        Detection of IBM 2741s is accomplished while the speed is

        set to 150 baud.  The user sends a 2741 style "eot" char-

        acter by pushing the attention key or by typing return;

        at 150 baud, this character looks like the ascii "~"

        (174 ).  Upon receipt of the "eot", the system is set to
            8
        operate 2741s and a "login: " message is typed.



        The user's name is terminated by a new-line or carriage-

        return character.  The latter results in the system being

        set to to treat carriage returns appropriately (see

        stty(II)).



        The user's name is scanned to see if it contains any

        lower-case alphabetic characters; if not, and if the name

        is nonempty, the system is told to map any future upper-

        case characters into the corresponding lower-case charac-

        ters.  Thus UNIX is usable from upper-case-only termi-

        nals.



        Finally, login is called with the user's name as argu-

        ment.



FILES           --



SEE ALSO        init(VII), login(I), stty(II)
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