如何在Perl中不阻塞地测试STDIN？

use strict;
use warnings;

while (1) {
    my $rin = '';
    my $rout = '';
    vec($rin, fileno(STDIN), 1) = 1;
    my $nfound = select($rout=$rin, undef, undef, 0.1);
    if ($nfound > 0) {
        my $input = <STDIN>;
        chomp $input;
        print "You entered: $input\n";
    } else {
        print "No input available\n";
    }
}