Alarm works on Win32, but not ALL the time such as when you do a blocking system calls like  $response = <stdin> Abigail explains why this is so. Here is a sub that I wrote that will get you around the <stdin> problem that uses Term::ReadKey. If you don't supply a sub handler... it will just use a default... this is pretty useful for getting input from the keyboard when you want to timeout... play with it... you will get the idea..

#!/perl/bin/perl -w

use strict;

my $input = &my_stdin( 
    prompt =>"Enter some text: ", 
    timeout => 3, 
    handler => \&my_alarm );

print "You entered: $input \n";


sub my_stdin {

    use Term::ReadKey;
    $| = 1;     #turn buffering off so we can see our print below
    my %args    = @_;
    my ($output,$key );
    my $prompt  = $args{'prompt'};
    my $timeout = $args{'timeout'};
    my $toh     = $args{'handler'};  # ref to a handler

    $SIG{ALRM} = $toh || sub { print "Timeout\n"; exit;};
    alarm($timeout);
    print $prompt;
    ReadMode 4;
    while(1){
        if(defined($key = ReadKey(-1))){
        my $val = ord $key;
        # 8 is backspace 10 and 13 are 
        $output .= $key unless $val == 8 || $val == 10 || $val == 13;
        #echo to the screen
        print $key if length $output > 0;          
        alarm($timeout);     #reset the alarm
            #last if the user hits return
        last if ( $val == 10 || $val == 13);
        # chop one if we get a backspace
        if( $val == 8 ){ chop $output; print " "; print chr(8); }
        }
    }
    ReadMode 0;
    print "\n";
    $output;
}

sub my_alarm{
    print "I just died because you waited too long!"; exit;        
}
[download]

Update: missing code added :-)
Update2: added code to handle backspaces

JamesNC