Select Code to Download

while (<>) {
}

if (data is available then) {
    while (<>) {
...
else {
    # do something else
}

    my $stdin = IO::Select->new(\*STDIN);
    open my $fh, '|-', $cmd or die $!;
...
        print {$fh} "\n" or die $!;
    }
    close $fh or die $!;

$ echo "text" | myprog

$ myprog <<EOT
some text
EOT

$ myprog afile