♥ << ruby

version.rb

#!/usr/bin/env ruby
# git tag -l       => 0.0.0
# version.rb patch => 0.0.1
# version.rb minor => 0.1.0
# version.rb major => 1.0.0

increments = [:major, :minor, :patch]
increment = ARGV[0].to_sym
raise ArgumentError.new(increments.join(' ')) unless increments.include? increment

components = %x{git describe --abbrev=0}.split(".").map(&:to_i)
components[ increments.index increment ] += 1
puts components.join('.')