How do I set Drupal's $base_path variable?

I can't find where this is set, but apparently it is because it is tacking on an unnecessary dir to 开发者_StackOverflow社区the base_url after I migrated from dev to live. I just want to set it to '/'

---

For Drupal 6 it's definitely in the settings.php file in your sites directory ( most likely drupal/sites/default/settings.php ).

I strongly assume that its the same for D7.