You can use -t STDIN to see if input is coming from a terminal and print your prompt if it is.

sub readprompt {
  my $prompt = shift;
  print $prompt if -t STDIN;
  <>;
}
while (my $i=readprompt(">>")) {
  print "You said: $i\n";
}
[download]

---
print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';
[download]