For some reason today,1 I just couldn’t find the correct instructions for forcing Spotlight to re-index using the Terminal. Therefore, I’m reposting the instructions here so this is easier to find in the future.

// First copy and paste this at the command prompt
sudo mdutil -E /

// Enter your password when prompted, and then paste this
sudo mdutil -i on /
  1. Listen, Google, Duck Duck Go is starting to look more attractive every day.