./13: un script Perl qui lit le fichier en entier en un seul coup et une forêt de s///g ressemblerait à:

use strict;
use File::Path;

# Files not explicitely closed on exit, but Perl does it for us.
package main;
    my $file;
    my $file2;
    my $filecontents;

    $file = $ARGV[0];
    $file2 = $ARGV[1];

    # Sanitize input file names - optional.

    # Slurp input file !
    open(INFILE,"$file") or die "Can't open $file: $!";
    read(INFILE, $filecontents, -s INFILE);
    close INFILE;

    $filecontents =~ s/jbsr\s+rename/.word 0xFnnn/g;
    $filecontents =~ s/jbsr\s+unlink/.word 0xFmmm/g;
    ...

    print $filecontents; # sur stdout
    # ou bien
    # open(OUTFILE, ">$file2") or die "Can't open $file2: $!";
    # print OUTFILE, $filecontents;
    # close OUTFILE;

En C/C++, c'est plus long à développer