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A text terminal or often just '''terminal''' (sometimes '''text console''') is a serial computer interface for text entry and display. Original text terminals were electronic Computer Terminal s connected to computers by a Serial Line , but later computers have built-in System Console s, and Terminal Emulator programs that work in a graphical Desktop Environment . Graphical displays have not eradicated the text terminal as it is convenient for computer programmers and appropriate for Command-line Interface s and Text User Interface s. Most programming languages support Standard Streams for inputting and printing text, and it is simplest to connect the streams to a text terminal. TYPES OF TEXT TERMINALS teleprinter]] ]] At first in the history of computers, Teleprinter s were used. Later, Computer Terminal s developed to have video displays. System Console is a text terminal used to operate a computer. Modern computers have a built-in keyboard and display for the console. Some operating systems such as Linux and FreeBSD have Virtual Console s to provide several text terminals on a single computer. Terminal Emulator is a computer program in a graphical Windowing System that let's the user operate a text terminal in a window. This lets text terminals coexist with modern Graphical User Interface s. Popular Terminal Emulator s include Win32 Console and '' Xterm ''. There are also specialized terminal emulators such as those used with modems. PuTTY is a terminal emulator and '' Ssh '' client. APPLICATIONS RUNNING ON A TEXT TERMINAL running the Cmd.exe shell]] text editor running in the Xterm terminal emulator]] The fundamental type of application running on a text terminal is a Command Line Interpreter Shell , which Prompts for commands from the user and executes each command after a press of ''Enter''. This includes Unix Shell s and some Interactive Programming environments. In a shell, most of the commands are small applications themselves. Another important application type is Text Editor . It occupies the whole area of display, shows a text document, and allows the user to edit the document. This has in part been replaced by Word Processor s. First word processors used text to communicate the structure of the document, but later work outside of the text terminal and simulate the final paper document in a graphical user interface. Programs such as Telix and Minicom control a Modem and the local terminal to let the user interact with remote servers. In the Internet , Telnet and Ssh work similarly. PROGRAMMING INTERFACE In the simplest form, a text terminal is like a file. Writing to the file displays the text and reading from the file produces what the user enters. In Unix-like operating systems, there are several Character Special File s that correspond to available text terminals. These include Virtual Console s /dev/tty1 etc., Serial Port s /dev/ttyS0 etc. and Pseudo Terminal s /dev/pts0 etc. There are also special files /dev/console, /dev/tty and /dev/tty0. Virtual consoles, computer terminals and modem lines can be configured in the file /etc/inittab read by '' Init '' -- typically it starts the text mode Login process ''getty'' for several virtual consoles. The programs used to control the device files include ''setserial'', ''setterm'' and ''stty''. The command '' Tty '' tells the name of the text terminal that it is run on. For other operations, there are special Escape Sequence s, Control Character s and termios Function s that a program can use, most easily via a library such as '' Ncurses ''. For more complex operations, the programs can use terminal special '' Ioctl '' system calls.EXTERNAL LINKS |
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