Add git branch to bash prompt. Green if OK; red if uncommitted changes or if ahead of master.

ps1_git_coloured.rb

#Based on http://www.furmanek.net/39/unix-prompt-for-usage-with-git/
green = "\033[0;32m"
reset = "\033[0m"
red   = "\033[0;31m"
current_branch = `git branch 2>/dev/null`.grep(/^\*/).first
if current_branch
  branch_name = current_branch.gsub(/^\*\s*/,'').strip

  status_lines = `git status`.split(/\n/)
  status = ( status_lines.length == 2 ) ? 'clean' : 'dirty'
  color = ( status == 'clean' ) ? green : red
  unless current_branch.empty?
    print "#{color}(#{branch_name})#{reset}"
  end
end

# Save as ~/git-ps.rb and put this in your .bashrc:
# parse_git_branch() {
#   ruby ~/git-ps.rb 2>/dev/null
# }
# export PS1="[\w \$(parse_git_branch)]> "