> > > Same for the "|-" variant that spawns another Ruby
> > > interpreter... how/why/when would you use this?
> > The "|-" is mostly like popen(). One reason to use it is to be able to use
> > OS-level sandboxing, like limiting a process size, chroot(), jail(),
> > setuid(), etc. For untrusted code (unstable or malicious).
[...]
> Hmm... I thought it could only be used for reading??? I don't see
> aPortname referenced anywhere but IO.foreach, IO.readlines, and
> IO#readlines...

Please ignore my garbage. Whatever is left of the Perl open() notation,
like "|-", probably is best left ignored (or removed from Ruby). What
replaces all special filenames starting with "|" is File.popen(). 

matju