But then you have to do the Module to Module-partial-path yourself, mentally. Not that hard, indeed. And one may actually prefer it that way. I wouldn't. However what's more important is that you're transversing all @INC recursively whereas you already know the potential locations for the wanted package. Also suppose you want to find the location of That::Particular::Foo. With your method unless I'm missing something, you're bound to search for 'Foo', and with your match you'll also get not only That::Other::Foo, but also That::Particular::eFoOZ. Last, there are indeed case insensitive (but case preserving) fs'es in widespread use, however case does matter for [Pp]erl, so I would most definitely avoid /i.

I would proceed like thus instead:

#!/usr/bin/perl 

use strict;
use warnings;
use File::Spec::Functions;

die "Usage: $0 <module> [<modules>]\n" unless @ARGV;

($\,$,)=("\n")x2;

for my $mod (@ARGV) {
    print "Searching for `$mod':";
    $mod =~ s{::}{/}g;
    $mod .= '.pm';
    
    my @results=grep -f, map {catfile $_, $mod} @INC;
    warn "`$mod' not found\n" and next unless @results;
    print @results, '';
}

__END__
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Of course if you don't mind your particular module being actually loaded, and you generally shouldn't care, then you may ask perl to tell you where it found it, inspecting %INC:

C:\temp>perl -MFile::Find -le "print $INC{'File/Find.pm'}"
C:/Programmi/Perl/lib/File/Find.pm
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