Department of Engineering

Terminal types

When an application starts in a text-only window (perhaps on an old-style text-only terminal, but more likely a terminal-emulation window on a graphics terminal) it needs to know what kind of facilities the terminal window provides (is colour available? - how big is the window?). Many terminal types exist. Programs determine what type of terminal they're being run on by inspecting the TERM environmental variable. You can print the value of this by typing print $TERM.

If you log directly into the Teaching System, TERM will be set to xterm, which suits the xterm terminal-emulation program that we use. If you log in from another machine, you'll be invited to choose a terminal type. vt100 (the default) is supported by most terminals.

If you pick a terminal type that your terminal doesn't understand, or that a program doesn't cope well with, you can try changing the terminal type by typing something like export TERM=vt100 then typing reset.

Programs determine the terminal window size by inspecting the LINES and COLUMNS variables. If you change the window size then these values usually change automatically, but programs already running within such a window might not notice the change.

If you want to run graphics programs remotely, setting the TERM variable won't help. You need to set the DISPLAY variable to be the display you're sat at, but you'll probably need to do more. Consult the X Security page. If you're using Xwin see the X-Win32 configuration page.