escher.rb

=begin
Single-file K/V database and query script.

This one also does compression (because disk I/O and efficiency and 
"best practices" and shut up, that's why).

Inspired by (and hopefully more ridiculous than) https://gist.github.com/4280027
=end

USAGE = <<END
{escher} -- one-file key-value storage.

Usage:
  Listing current keys:
  $ {escher}

  Getting the value of the foo key:
  $ {escher} foo

  Setting the value of foo to bar:
  $ {escher} foo bar

  Removing the key foo:
  $ {escher} foo ""

  Removing everything:
  $ {escher} --clean

  Printing this help message:
  $ {escher} --help
END

require 'base64'
require 'zlib'

$data = Marshal.load(Zlib::Inflate.inflate(Base64.decode64(DATA.read)))
$changed = false

END {
  if $changed
    me = __FILE__
    curr = File.read(me)
    code, data = curr.split(/^__END__$/)
    b64_data = Base64.encode64(Zlib::Deflate.deflate(Marshal.dump($data)))
    open(me, 'w') {|fh| fh.write("#{code}__END__\n#{b64_data}") }
  end
}

case ARGV.size
when 0
  puts $data.keys.join("\n")
when 1
  arg1 = ARGV.shift
  case arg1
  when '--clear'
    $data = {}
    $changed = true
  when '--help'
    STDERR.puts(USAGE.gsub(/{escher}/, File.basename(__FILE__)))
    exit
  else
    puts $data[arg1]
  end
when 2
  key, val = ARGV
  if val == ""
    $data.delete(key)
  else
    $data[key] = val
  end
  puts val
  $changed = true
end

__END__
eJxj4ahmAAABIgCI

This is better than the original in multiple ways. I've just commited a revision to my implementation that borrows some of your ideas.