Link pre-installed apps to Homebrew Cask I installed Slack by downloading the DMG from its website and copying the app bundle into /Applications directory. Alternatively, I could have used brew cask install slack.

Is there a way to make Homebrew aware of this drag-and-drop version of Slack ? Or do I need to remove it and install via brew cask in order for it to be detected by Homebrew?
I have found the best way to fix this issue is brew cask reinstall &lt;cask&gt;. Homebrew then removes the old version as if it installed it and the new version is now managed. That for me has been the cleanest solution.