>You, like many others, underestimate Tcl. Not in this case, at least :-), since on that wiki page there is one implementation of command pipes that I wrote an

>You, like many others, underestimate Tcl. Not in this case, at least :-), since on that wiki page there is one implementation of command pipes that I wrote and a link to another (in fptools). What I mean when I say that "you cannot pipe to or from functions" is that while you can pipe data from one external process to another in an [exec] command, you can't pipe it from an external process to a proc or vice versa, which would be analogous to what the POSIX shell can do. Functions and external processes are less similar in Tcl than they are in sh. The best you can do with a simple command pipe implementation like those on the wiki page is pipe data from [exec foo] to [bar $arg] to [exec baz << $arg], which, unlike [exec foo | baz], will read foo's entire output before passing it along. The only real solution that I know to allow you to treat snippets of Tcl code and external processes as basically interchangeable in a gradually read pipeline is rkeene's pipethread library. I am a big fan of it, but using an external dependency that isn't in your operating system's package repositories adds considerable friction to writing and distributing a simple script. (I do hope pipethread ends up in Tcllib.)