Linux Fu: Controlling the Terminal

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The most fundamental question you have to ask is what kind of terminal are you talking to. The answer is in the $TERM environment variable and if you ask your shell to print that variable, you’ll see what it thinks you are using: echo $TERM.

For example, a common type is vt100 or linux console. This is usually set by the system and you shouldn’t change it unless you have a good reason. In theory, of course, you could manually process this information but it would be daunting to have to figure out all the way to do something like clear the screen on the many terminals Linux understands.

That’s why there’s a terminfo database. On my system, there are 43 files in /lib/terminfo (not counting the directories) for terminals with names like dumbcygwinansisun, and xterm. Looking at the files isn’t very useful since they are in a binary format, but the infocmp program can reverse the compilation process. Here’s part of the result of running infocmp and asking for the definition of a vt100:

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