#!/usr/bin/perl
use strict;
use warnings; 
use File::Spec;

my $dir_name='C:\Desktop\Plots\Abflusswerte';
my $file_out='hq_regio_neu.txt';

opendir( my $DIR,$dir_name) or die("ERROR open dir $dir_name ($!)\n"); 
my @files = readdir($DIR);
closedir($DIR);


open(my $OUT,'>>',$file_out) or die("ERROR open file $file_out ($!)\n");

for my $file_name (@files)
{
  my $file_path=File::Spec->join($dir_name,$file_name);
  if(open(my $IN, '<', $file_path))
  {
    while(my $line=<$IN>)
    {
      print $OUT $line;
    }
    close($IN);
  }
  else
  {
    warn("ERROR open $file_path ($!)\n");
  }
}