Monday, July 27, 2009

TTY and PTS

tty is a Unix command that prints to standard output the name of the file connected to standard input. The name of the program comes from teletypewriter, abbreviated "TTY".

pts stands for pseudo terminal slave. A terminal (or console) is a keyboard/screen combination you sit and type at. Old UNIX boxes would have dozens of them hanging off the back, all connected with miles of cable. A pseudo terminal provides just the same facility only without the hardware. In other words, it's an xterm window or a konsole window, or whatever utility you use. They pop into life as you ask for them and get given sequential numbers: pts/0, then pts/1 and so on.