you mean something like this?

use warnings 'all';
use strict;
use autodie;

    open my $input, '<', $ARGV[0];
    open my $out,   '>', 'hex.txt';

        while (my $sentence = <$input>) {
    
            my $substring = '...pck.*?\.c';
            $sentence =~ s{$substring}{}; 
        print $out unpack 'H*', $sentence;             
 
    }
[download]

and thank you for the nice explanations :D