11/3/71                                       LOGIN, LOGOUT (VII)

NAME            logging in and logging out

SYNOPSIS        --

DESCRIPTION     UNIX must be called from an appropriate terminal.

                The two general classes of terminals which UNIX

                supports are typified by the 37 Teletype on the

                one hand and the GE TermiNet 300 and Memorex 1240

                on the other.  The principal difference is the

                baud rate (150 vs. 300) and the treatment of the

                carriage return character.  Most terminals oper-

                ating at 150, 300, or 1200 baud using the ASCII

                character set either work (more or less) at the

                moment or can be used by special arragement.  In

                particular, special arrangement is necessary for

                terminals which do not generate lower-case ASCII


                It is also necessary to have a valid UNIX user ID

                and (if desired) password.  These may be ob-

                tained, together with the telephone number, from

                the system administrators.

                The same telephone number serves terminals oper-

                ating at both the standard speeds.  When a con-

                nection is established via a 150-baud terminal

                (e.g. TTY 37) UNIX types out "login:"; you re-

                spond with your user name, and, if a mask is

                typed, with a password.  If the login was suc-

                cessful, the "@" character is typed by the Shell

                to indicate login is complete and commands may be

                issued.  A message of the day may be typed if

                there are any announcements.  Also, if there is a

                file called "mailbox", you are notified that

                someone has sent you mail.  (See the mail com-


                From a 300-baud terminal, the procedure is

                slightly different.  Such terminals often have a

                full-duplex switch, which should be turned on (or

                conversely, half-duplex should be turned off).

                When a connection with UNIX is established, a few

                garbage characters are typed (these are the "lo-

                gin:" message at the wrong speed).  You should

                depress the "break" key; this is a speed-

                independent signal to UNIX that a 300-baud termi-

                nal is in use.  It will type "login:" (at the

                correct speed this time) and from then on the

                procedure is the same as described above.

                Logging out is simple by comparison (in fact,

                sometimes too simple).  Simply generate an end-

                of-file at Shell level by using the EOT charac-

                ter; the "login:" message will appear again to

                indicate that you may log in again.

                It is also possible to log out simply by hanging

                up the terminal; this simulates an end-of-file on

                the typewriter.

FILES           --

SEE ALSO        init


BUGS            Hanging up on programs which never read the type-

                writer or which ignore end-of-files is very dan-

                gerous; in the worst cases, the programs can only

                be halted by restarting the system.

OWNER           ken, dmr