plumbing [UNIX] n. Term used for shell code, so called because of the prevalence of `pipelines' that feed the output of one program to the input of another. Under UNIX, user utilities can often be implemented or at least prototyped by a suitable collection of pipelines and temp-file grinding encapsulated in a shell script; this is much less effort than writing C every time, and the capability is considered one of UNIX's major winning features. A few other OSs such as IBM's VM/CMS support similar facilities. Esp. used in the construction `hairy plumbing' (see hairy). "You can kluge together a basic spell-checker out of `sort(1)', `comm(1)', and `tr(1)' with a little plumbing." See also tee.