"In other words, you want to be able to see if there's a reason to process input without stopping your program to wait for it. AND you want it to work even if the user had redirected input." -- marinersk

Indeed. My objective is to collect input from any & all of the ways, as in command | program.pl file < file2.

"Not sure why you wish to avoid using Term::Readkey but without that I would expect you to not find a solution." -- marinersk

It is not that I want to avoid use of T::R. I am|was curious if I might have missed something otherwise obvious to others (say on the lines of readline, sysread, select, tell, etc).