Another way to implement a timeout on a user input read (that is what you're doing, right?) is to use Term::ReadKey and its ReadLine method (or ReadKey, but here you want to read a line, so...).

    use Term::ReadKey;
    my $message = ReadLine(10);    ## timeout of 10 seconds
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This manages all of the timeout issues for you. Although it may not do so in a way that suits you, who knows. And you may already have tried it, even. Anyway.