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System Management Guide: Communications and Networks

TTY Overview

A tty terminal device is a character device that performs input and output on a character-by-character basis. The communication between terminal devices and the programs that read and write to them is controlled by the tty interface. Examples of tty devices are:

The tty devices can be added, deleted, listed, and changed like any other device on your system by using the Web-based System Manager Devices application, the SMIT tool, or device-specific commands.

TERM Values for Different Displays and Terminals

Information about terminal capabilities is stored in the terminfo database. The value of the TERM environment variable identifies the specific terminal description in the terminfo database. This provides all information that a program needs for communicating effectively with the current tty device.

TERM Values for Various Terminals
Display/Terminal Value
3161 ASCII Terminal ibm3161
3163 ASCII Terminal ibm3161
DEC VT100 (terminal) vt100
DECVT220 vt220
3151 ASCII Display Station with Cartridge or 3161 ASCII Display Station with Cartridge ibm3161-C
3162 ASCII Display Station ibm3161
3162 ASCII Display Station with Cartridge ibm3162
6091 Display lft
AIXwindows aixterm

For information about the entries in the terminfo database, see the terminfo file format. To convert termcap entries into terminfo entries, see the captoinfo command. (The termcap file contains the terminal descriptions for older Berkeley systems.)

Setting TTY Characteristics

The line discipline provides the hardware-independent user interface for communicating between the computer and an asynchronous device. For example, a user is able to erase a single line or to interrupt a currently running process by typing a particular sequence of characters. You can define the meaning of these character sequences as well as set other terminal characteristics, such as the communication speed, by using the Web-based System Manager Devices application, the chdev command, the System Management Interface Tool (SMIT), or the stty command.

Most applications (including shells and editors) are designed to interface with terminals using the POSIX line discipline (default). You can change to the Berkeley line discipline by using the stty command.

Setting Attributes on the Attached TTY Device

For correct communication between the host and an attached tty device, the following are required:

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