6/15/72 LOGIN, LOGOUT (VII) NAME logging in and logging out SYNOPSIS -- DESCRIPTION UNIX 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 terminals on the other. Not all installations support all these termi- nals. Often the M33/35 Teletype is supported in- stead of the 2741. Depending on the hardware in- stalled, most terminals operating at 110, 134.5, 150, or 300 baud can be accommodated. To use UNIX, it is also necessary to have a valid UNIX user ID and (if desired) password. These may be obtained, together with the telephone num- ber, from the system administrators. The same telephone number serves terminals oper- ating at all the standard speeds. The discussion below applies when the standard speeds of 134.5 (2741's) 150 (TTY 37's) and 300 (Terminet 300's) are available. 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 re- quested, with a password. (The printer is turned off while you type the password.) 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 com- mand.) 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. From a 2741, no message will appear. After the telephone connection is established, press the "ATTN" button. UNIX should type "login:" as de- scribed above. If the greeting does not appear after a few seconds, hang up and try again; some- thing has gone wrong. If a password is required, the printer cannot be turned off, so it will ap- pear on the paper when you type it. 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 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 /etc/motd may contain a message-of-the-day. SEE ALSO init(VII), getty(VII), tty0(IV) DIAGNOSTICS -- 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