use strict;
use warnings;

my $str='\334ber@n\374ber.com';
$str =~ s/\\([0-7]+)/pack('U', oct('0'.$1))/eg;
binmode STDOUT, ":encoding(UTF-8)";
print "$str\n";
print utf8::is_utf8($str) ? "str is ...utf8\n" : "str is ...not utf8\n";

use 5.010;
use utf8::all;

my $string='\334ber@n\374ber.com';
$string =~ s/\\([0-7]+)/chr oct $1/eg;
print "$string\n";
print utf8::is_utf8($string) ? "string is ...utf8\n" : "string is ...not utf8\n";

my $string='\334ber@n\374ber.com';
$string =~ s/\\([0-7]+)/chr oct $1/eg;
utf8::upgrade($string);
print "$string\n";
print utf8::is_utf8($string) ? "string is ...utf8\n" : "string is ...not utf8\n";