A short piece of pipe having a lateral outlet, used to connect a line of pipe with a pipe at a right angle with the line; -- so called because it resembles the letter T in shape.
The letter T, t; also, something shaped like, or resembling in form, the letter T.
To copy text from a pipe into a file. tee is most useful for making a log of the output of a slow or long-running program while still seeing its output on-scree. It's also good for debugging scripts so that you can see what's coming out of one program and going into another.