Problem

You want to know whether keyboard input is waiting without actually reading it.

Solution

Use the CPAN module Term::ReadKey, and try to read a key in non-blocking mode by passing it an argument of -1 :

use Term::ReadKey;  ReadMode ('cbreak');  if (defined ($char = ReadKey(-1)) ) {     # input was waiting and it was $char } else {     # no input was waiting }  ReadMode ('normal');                  # restore normal tty settings

Discussion

The -1 parameter to ReadKey indicates a non-blocking read of a character. If no character is available, ReadKey returns undef .

See Also

The documentation for the Term::ReadKey module from CPAN; Recipe 15.6