.he '6/15/72''LOGIN, LOGOUT (VII)'
NAME logging in and logging out
must be called from an appropriate terminal.
UNIX supports ASCII terminals typified by the Teletype M37,
the GE Terminet 300, the Memorex 1240, and various
graphical terminals on the one hand, and IBM 2741-type
Not all installations support
Often the M33/35 Teletype is supported instead
Depending on the hardware installed, most
terminals operating at 110, 134.5, 150, or 300 baud can
it is also necessary to have
a valid UNIX user ID and (if desired) password. These
may be obtained, together with the telephone number, from the system administrators.
The same telephone number
serves terminals operating at all the standard speeds.
The discussion below applies when the standard
150 (TTY 37's) and 300 (Terminet 300's)
When a connection is established via a 150-baud terminal
(e.g. TTY 37) UNIX types out "login:"; you respond with
your user name, and, if requested, with a password.
(The printer is turned off while you type the
If the login was successful, 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
\b\b\b\b____ command.)
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 "login:" message at the wrong speed).
You should depress the "break" key;
this is a speed-independent signal to UNIX that a 300-baud
terminal is in use. It will type "login:" (at the correct speed
this time) and from then on the procedure is the same as described
From a 2741, no message will appear.
After the telephone connection is established,
UNIX should type "login:" as described above.
If the greeting does not appear after a few seconds,
hang up and try again; something has gone wrong.
If a password is required,
the printer cannot be turned off, so it will appear on the paper
For more information, consult
getty(VII), which discusses the login sequence in more
detail, and tty0(IV), which discusses typewriter I/O.
Logging out is simple by comparison (in fact, sometimes too simple).
Simply generate an end-of-file at Shell level by using
the EOT character; 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.
may contain a message-of-the-day.
SEE ALSO init(VII), getty(VII), tty0(IV)
on programs which never read
the typewriter or which ignore end-of-files
is very dangerous; in the worst cases,
the programs can only be halted by restarting the system.
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