use Getopt::Long;

my $filename   = "";
my $pattern = "";

my $result = GetOptions ("file=s"   => \$filename,      # string
                        "pattern=s"  => \$pattern);  # flag
);

my $text;
# Daten einlesen
open (my $fh, "<", $filename) or die "ERROR: File $filename not opened: $!\n";
while ($text = <$fh>) { # zeilenweise Text aus Datei $filename einlesen
  my $ret = ermorde_Knuth($text, $pattern);
  if ($ret != -1) {
    print "Treffer $ret von $pattern in $text\n";
  }
}
close($fh) or die "ERROR: File $filename not closed: $!\n";