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

I created a tool to ease the process prescribed in this answer.

To find a package pkg with version a.b.c, run:

$ brew-install-specific pkg@a.b.c

This will list commits on the pkg homebrew formula that mention the given version along with their GitHub urls.

Matching versions:
1. pkg: update a.b.c bottle.
   https://github.com/Homebrew/homebrew-core/commit/
2. pkg: release a.b.c-beta
   https://github.com/Homebrew/homebrew-core/commit/
3. pkg a.b.c
   https://github.com/Homebrew/homebrew-core/commit/

Select index: 

Verify the commit from the given URL, and enter the index of the selected commit.

Select index: 2
Run:
  brew install https://raw.githubusercontent.com/Homebrew/homebrew-core//Formula/pkg.rb

Copy and run the given command to install.