use warnings;
use strict;
my $AllDevices='All_Devices.txt';
my $_AllConfDir = '.';

# Listing the devices

opendir (my $dir ,$_AllConfDir) or die "Error in opening dir $_AllConfDir\n";
open my $a, ">>",  $AllDevices
	or die "couldn't open file '$AllDevices for appending: $!";

while ( my $file = readdir($dir)) {
     print $a "$file\n";
     print "$file\n"; 
}
closedir $dir or warn $!;
close $a or warn $!;