git_ps1.rb

#!/usr/bin/ruby
def git_branch 
  (%x{git branch 2> /dev/null}.grep(/^\*/).first || '').gsub(/^\* ([a-z0-9_]+)[[:space:]]+$/i, '\1')
end

def set_color color
  "\033[#{color}m"
end

def print_result result
  print "#{set_color('37')}(#{result}#{set_color('37')}#{set_color('00')})"
end

if git_branch == 'master'
  print_result "#{set_color('41')}#{set_color('32')}#{git_branch}"
elsif !git_branch.empty?
  print_result "#{set_color('32')}#{git_branch}"
end