With Perl's in-memory filehandles I get "run3(): Bad file descriptor redirecting STDIN at ...". With IPC::Run and, again, with Perl's in-memory filehandles, script just dies without giving any reason "at C:/PDL24/perl/vendor/lib/IPC/Run.pm line 1852." With references to scalars, IPC::Run works, it seems, just like IPC::Run3.

The IPC::Run documentation is a bit overwhelming, I'll browse through it, at leisure :)

As to "premature optimization" - of course, the solution with IPC::Run3 and temp files will work fine. It's not that something is broken and I'm desperate and asking someone to do a research for me. I just thought maybe there already is (and has been for a long time) some FAQ list with nicely enumerated items, etc. :) Thank you for answer.