Note that the hexdump of your input data has a Byte Order Mark (BOM) at the front of it, which Perl counts at least as some characters.

Discounting the BOM, I get the expected output with the following program:

#!/usr/bin/perl -w
use strict;
use Encode qw/encode decode/;

open (INFILE, "<:encoding(UTF-8)", "utf8.txt") || die "blah blah blah"
+;
open (OUTFILE, ">:encoding(UTF-8)", "oututf8.txt") || die "blah blah";
binmode STDOUT, ':encoding(UTF-8)';

print "Ruler : [12345678901234567890]\n";
while (my $line = <INFILE>) {
  chomp ($line);
  print "Input : [$line]\n";
  my $linestart = substr($line,0,20);
  my $outline = $linestart;
  print "20    : [$outline]\n";
  print "---\n";
  print OUTFILE "$outline\n";
}
close (INFILE);

[download]

To remove the BOM at the start of your file, use maybe simply

$line =~ s!^\N{BYTE ORDER MARK}!!;

[download]

In reply to Re^3: Read and write UTF-8 by Corion
in thread Read and write UTF-8 by Norah

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