foreach my $file (@fileet) {
        my $newfile = $file;
        $newfile =~ s/ä/ä/g;
        $newfile =~ s/ö/ö/g;
        move("$file", "$path/$newfile");
}
[download]

Thanks, there is still a problem, because this code does not rename those files. What should I do?

#!/bin/perl

#usage:
#C:\Perl>perl Print_dir_sizes.pl "C:/Perl/"
use warnings;
use strict;
use File::Copy;

my $path = $ARGV[0];
die "You must supply a full directory path" unless (-e $path && -d $pa
+th);

my @dirs;

opendir(DIR, $path) || die "can't opendir $path: $!";
my @fileet = grep { -f "$path/$_" } readdir(DIR);
closedir(DIR);

foreach my $file (@fileet) {
        my $newfile = $file;
        $newfile =~ s/ä/ä/g;
        $newfile =~ s/ö/ö/g;
        move("$file", "$path/$newfile");
}
[download]

Oh yes, I found it:

foreach my $file (@fileet) {
        my $newfile = $file;
        $newfile =~ s/ä/ä/g;
        $newfile =~ s/ö/ö/g;
        move("$path/$file", "$path/$newfile");
}
[download]

The error was here

move("$path/$file", "$path/$newfile");
[download]