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Additional methods for the IO class on Unix platforms

README
= Description
  The io-extra library provides a few extra IO methods that you may find
  handy. They are IO.closefrom, IO.fdwalk, IO.pread, IO.pread_ptr, IO.pwrite,
  IO.writev, IO#directio? and IO#directio=.
	
  This library is not supported on MS Windows.

  Support for OS X is limited. See below for details.

= Installation
  gem install io-extra

= Synopsis
  require 'io/extra'

  # Close all file descriptors from 3 up.
  IO.closefrom(3)

  # Inspect all the open handles
  IO.fdwalk(0){ |handle|
    puts "=" * 40 
    p handle
    p handle.fileno
  }

  # Write an array to an IO object efficiently
  IO.writev(fh.fileno, %w[a b c])

= Developer's Notes
  You might be wondering what the difference is between my implementation of
  IO.closefrom and a pure Ruby version that looks something like this:

  def IO.closefrom(n)
    0.upto(n) do |fd|
      IO.for_fd(fd).close
    end
  end

  The primary difference is that this walks all file descriptors, rather
  than only open file descriptors. However, I should note that this only
  applies if your platform supports the closefrom() function. In that case,
  the only advantage is speed.

  You might also be wondering what the difference is between my implementation
  of IO.fdwalk and a pure Ruby version that looks something like this:

   def IO.fdwalk(n)
      ObjectSpace.each_object(File){ |f|
         yield f if f.fileno >= n
      }
   end

  The primary difference is that this only closes Ruby file objects, not
  necessarily every file handle opened by the Ruby process. For example, handles
  opened via system() calls.

= Note to OS X Users
  The OS X platform does not support closefrom() or fdwalk(). The hand-
  crafted IO.closefrom function will not work because the getrlimit()
  function on OS X does not work. Patches welcome.

= Documentation
  For further documentation, see the io_extra.txt file or the inline
  documentation that was generated by RDoc (if you did a gem install).

= Known Issues
  The IO.writev tests fail on Solaris. Short test scripts seem to work,
  however. We're not sure what the issue is yet. Help wanted.

  Please file any bug reports on the project page at
  https://github.com/djberg96/io-extra

= Future Plans
  * Switch from C extension to FFI.

= Acknowledgements
  Eric Wong for some great work on Linux compatibility and other fixes, as
  well as the code for the IO.writev method.

= License
  Artistic 2.0

= Copyright
  (C) 2003-2013 Daniel J. Berger
  All Rights Reserved
    
= Warranty
  This package is provided "as is" and without any express or
  implied warranties, including, without limitation, the implied
  warranties of merchantability and fitness for a particular purpose.
	 
= Author
  Daniel J. Berger
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