Homebrew install specific version of formula?

Question

How do I install a specific version of a formula in homebrew? For example, postgresql-8.4.4 instead of the latest 9.0.

Answer 1

There's now a much easier way to install an older version of a formula that you'd previously installed. Simply use

brew switch [formula] [version]

For instance, I alternate regularly between Node.js 0.4.12 and 0.6.5:

brew switch node 0.4.12
brew switch node 0.6.5

Since brew switch just changes the symlinks, it's very fast. See further documentation on the Homebrew Wiki under External Commands.