SyStem> A Unix command which copieS itSStandard input to itSStandard output (like cat) but alSo to a file given aS itS argument. tee iS thuS uSeful in pipelineS of Unix commandS (See plumbing) where it allowS you to create a duplicate copy of the data Stream. E.g. egrep Unix Dictionary | tee /dev/tty | wc -l SearcheS for lineS containing the String "Unix" in the file "Dictionary", printS them to the terminal (/dev/tty) and countS them. Unix manual page: tee(1). [Jargon File] (1996-01-22)