myscript some.data > output

# or

grep -h foo *.data | sort -u | myscript > output

##</code><code>##

binmode STDIN, ":utf8";

##</code><code>##

#!/usr/bin/perl

binmode STDIN, ":utf8";  # covers pipe input
binmode ARGV, ":utf8";   # does not work -- handle isn't open yet

while (<>) { do_whatever( $_ ) }

##</code><code>##

#!/usr/bin/perl

use strict;

my @files;
if ( @ARGV ) {
    @files = @ARGV;
}
elsif ( -t ) {
    die "I want file names to open, or else pipeline input";
}
else {
    @files = "stdin";
}

for my $file ( @files ) {
    my $fh;
    if ( @ARGV ) {
        open $fh, "<:utf8", $file;
    } else {
        binmode STDIN, ":utf8";
        $fh = \*STDIN;
    }
    while (<$fh>) { do_whatever( $_ ) }
}