A minimal command line tool to split multi-entity PEM files into a collection of files each containing only one entity.

pemsplit.rb

#!/usr/bin/env ruby
# encoding: UTF-8
=begin
Copyright Alexander E. Fischer <aef@raxys.net>, 2012

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
=end

# A minimal command line tool to split multi-entity PEM files into a collection
# of files each containing only one entity. Requires Ruby >= 1.9.2.

require 'pathname'

∞ = Float::INFINITY

ARGV.map{|file| Pathname.new(file) }.each do |file|
  file.open do |input_io|

    1.upto(∞).each do |split_index|
      split_file = Pathname.new(file.to_s + ".#{'%03d' % split_index}")
  
      begin
        while line = input_io.readline
          output_io ||= split_file.open('w')
          output_io << line
          
          if line =~ /-----END [^\-]+-----/
            break
          end
        end
      rescue EOFError
        break
      ensure
        if output_io
          output_io.close
          output_io = nil
        end
      end

    end
  end
end