sub getParam {
  
  if ($someCondition) {
    return 0
  }
  ...
  return 1;
}

sub execCommand {

  ...
  if (! &func1()) {
    return 0;
  }
  ...
  return 1;
}

sub func1 {

  ...
  if (! &getParram()) {
    return 0;
  }
  ..
  return 1;
}

# CLI main loop
while ($input = $term->readline("\n$prompt > %n", $TRUE)) {
  &execCommand($input);
}