split_file.rb

gistfile1.rb

#!/usr/bin/ruby
file = 'test.txt'
split_line_size = 3
file_cnt = 0
out = open('dummy.txt', 'w')

open(file).each_with_index do |line, i|
  if i % split_line_size == 0
    out.close unless out.closed?
    out = open("split#{file_cnt}.txt", 'w')
    file_cnt += 1
  end
  out.write line
end