use strict;
use warnings;

use IO::Prompt;

while( prompt "next: " ) {
  print "You said '$_'\n";
}

##</code><code>##

$ cat > test.txt
Hello
World
^D
$ perl ./prompt.pl < test.txt
You said: Hello
You said: World
$ cat test.txt | perl ./prompt.pl
You said: Hello
You said: World

##</code><code>##

use strict;
use warnings;

use IO::Interactive qw(is_interactive);

if (is_interactive){
  print "interactive\n";
} else {
  print "piped\n";
}

##</code><code>##

$ perl ./interactive.pl
intereactive
$ cat test.txt | perl ./interactive.pl
piped
$ perl ./interactive.pl < test.txt
piped