This currently only works on Linux.
I wrote this because I wanted in-memory streams when running programs with external-program, and found flexi-streams didn't work. That led to meandering about reading up on streams, and then I ended up here. Also, Unix programming in Lisp is a fun thing.
CL-USER> (defvar *pipes* (unix-pipes:pipe :element-type 'character))
*PIPES*
CL-USER> (format (second *pipes*) "Hello, world~%~%")
NIL
CL-USER> (force-output (second *pipes*))
NIL
CL-USER> (read-line (first *pipes*))
"Hello, world"
NIL
CL-USER> (mapcar #'close *pipes*)
(T T)
Copyright (c) 2015 Kyle Isom <kyle@metacircular.net>
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"MagrittePipe" by Image taken from a University of Alabama site, "Approaches to Modernism": [1]. Licensed under Fair use via Wikipedia - https://en.wikipedia.org/wiki/File:MagrittePipe.jpg#/media/File:MagrittePipe.jpg