updates = File.read("updates") paths = `find data -name '*.md'`.split("\n") paths.each do |path| input = File.read(path) updates.split("\n").each do |line| split = line.split(" ") old_id = split[0] new_id = split[1] input = input.gsub(old_id, new_id) end File.write(path, input) end