## problem: prints all columns from specified files but ignores the $nextUnless specification - why?

The reason for this is that the line number $. doesn't reset for all the files (in @ARGV) unless you close ARGV at the end of each file.

You need to add this line as the last line in your 'while' loop'

close ARGV if eof;

UPDATE: This only addresses a small part of the problem. Looking at your code above, why are you opening a file (and not use it), then push that file to '@ARGV'?