#!/usr/bin/env perl
use warnings;
use 5.012;
use utf8;
use open ':encoding(utf-8)';
use open ':std';

open my $fh,'>','test.txt' or die $!;
say $fh 'käse';
close $fh;

open my $fh1,'<','test.txt' or die $!;
while ( my $row = readline( $fh1 ) ) {
    print $row;
}
close $fh1;

use autodie;

open my $fh2,'test.txt';
while ( my $row = readline( $fh2 ) ) {
    print $row;
}
close $fh2;

# Output:
# käse
# käse