# This forks implicitly
my $child_pid = open my $child_fh, '-|';
if ( ! defined $child_pid ) {
    die "Can't fork: $!";
}
if ( $child_pid ) {
    # parent

    print while ( <$child_fh> );

    # this implicitly waits for the child
    close $child_fh or die "close on pipe failed: $!";
}
else {
    # child

    # child's STDOUT is connected to the pipe
    print "Line 1\n";
    print "Line 2\n";

    exit;
}