FAQ 8.37 How do I find out if I'm running interactively or not?

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8.37: How do I find out if I'm running interactively or not?

    (contributed by brian d foy)

    This is a difficult question to answer, and the best answer is only a

    What do you really want to know? If you merely want to know if one of
    your filehandles is connected to a terminal, you can try the "-t" file

            if( -t STDOUT ) {
                    print "I'm connected to a terminal!\n";

    However, you might be out of luck if you expect that means there is a
    real person on the other side. With the "Expect" module, another program
    can pretend to be a person. The program might even come close to passing
    the Turing test.

    The "IO::Interactive" module does the best it can to give you an answer.
    Its "is_interactive" function returns an output filehandle; that
    filehandle points to standard output if the module thinks the session is
    interactive. Otherwise, the filehandle is a null handle that simply
    discards the output:

            use IO::Interactive;
            print { is_interactive } "I might go to standard output!\n";

    This still doesn't guarantee that a real person is answering your
    prompts or reading your output.

    If you want to know how to handle automated testing for your
    distribution, you can check the environment. The CPAN Testers, for
    instance, set the value of "AUTOMATED_TESTING":

            unless( $ENV ) {
                    print "Hello interactive tester!\n";


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