$ perl -Mutf8 -wE 'say "e-acute: é; u-acute: ú"'
e-acute: ?; u-acute: ?

##</code><code>##

$ perl -Mutf8 -wE 'binmode STDOUT => ":utf8"; say "e-acute: é; u-acute: ú"'
e-acute: é; u-acute: ú

##</code><code>##

$ perl -Mutf8 -wE 'use open OUT => qw{:utf8 :std}; say "e-acute: é; u-acute: ú"'
e-acute: é; u-acute: ú

##</code><code>##

open my $fh, '>:encoding(UTF-8)', $filename

##</code><code>##

use autodie;
...
open my $in_fh, '<', $infile;
open my $out_fh, '>', $outfile;