Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I want to set up a menu for my program and then have different letters point to different options. I would like it if the user could just press the letter and then be taken to that option without being forced to press the enter key. Does anyone know how I might go about doing this?

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Re: How do I read just one key at a time?
by plaid (Chaplain) on Feb 29, 2000 at 00:32 UTC
    No modules in the standard distribution (that I could find) will do this, but take a look at the Curses and the Term::ReadKey modules at CPAN. One or both of those can do what you're looking for.
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Re: How do I read just one key at a time?
by Crulx (Monk) on Feb 29, 2000 at 14:24 UTC
    Yeah, I probably would use a CPAN module that already has the nonblocking IO and select polling set up for you. But it would be wise anyway to learn how to do nonblocking IO and using select to do your polling. These are very important things in unix and perl has basically the same syntax for them as C. Remember not to confuse the different types of "select"s in perl. W. Steven's Advanced Programming in the Unix Environment is an essential book for anyone programming something on Unix.
    ---
    Crulx
    crulx@iaxs.net
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      Getting input one character at a time doesn't involve using select and non-blocking I/O (at least not the easiest way). The way that the input is processed is set by the user's terminal. The default setting is known as 'canonical mode', which processes line-by-line. I also must correct my original statement, for there is indeed a way with the standard perl modules to do what you want. For example: 
      use POSIX qw(:termios_h);

my $termios = new POSIX::Termios;

$termios->setlflag(~ICANON);     # Turn off canonical mode
$termios->setcc(VMIN, 1);        # Read a min of 1 character
$termios->setcc(VTIME, 0);       # No time-out on reads
$termios->setattr(0, TCSANOW);   # Apply settings to STDIN

while(read(STDIN, $key, 1)) {
        print "Got: $key\r\n";
}

      [download]
      or something similar will work. The flags and function calls used by the POSIX::Termios module are nearly identical to the corresponding ones in C.
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[d/l]
        My PERL distribution doesn't have Curses or Posix::Term installed. I tried your last example but how do you get the terminal settings back to normal afterwards? I couldn't find documentation on this.
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