Cool.

I'm puzzled by the temporary variable - why not:

echo-literally-helper() {
  history 1 | perl -pe 's/^ *[0-9]+ +[^ ]+ //'
}

Because it's example code, and the real aim is to illustrate that once you've got $str, you can do further string processing on it in any fashion you like. The echo command is really a placeholder for "now do stuff of your choice with".