instructions.md

Copy this script to ".git/hooks/post-checkout" in your repository and make it executable:

chmod +x .git/hooks/post-checkout

Tweak it at will. I'm refreshing the bundle and restarting the app server because the Gemfile is different on my "hosted" branch than on other branches.

post-checkout.rb

#!/usr/bin/env ruby -wKU
old, head, flag = ARGV

# your branch name here
target_branch = 'hosted'

if flag == "1" # switching branches
  branches = `git name-rev --name-only #{old} #{head}`.split("\n")
  if branches.include?(target_branch)
    puts 'checking bundle, restarting app ...'
    system 'bundle check'
    system 'touch tmp/restart.txt'
  end
end