use strict;
use warnings;

while (<DATA>) {
    chomp;
    my @parts = split /\./;
    pop @parts;
    my $file_no_ext = join '.', @parts;
    print "file_no_ext = $file_no_ext\n";
}

__DATA__
foo.bar.txt
goo.doc
boo.hoo.moo
[download]

prints:

file_no_ext = foo.bar
file_no_ext = goo
file_no_ext = boo.hoo
[download]