diff -r 10eaab5887cd Lib/shutil.py
--- a/Lib/shutil.py	Mon Apr 23 14:25:19 2012 +0800
+++ b/Lib/shutil.py	Tue Apr 24 04:40:00 2012 -0700
@@ -921,3 +921,82 @@
             lines = size.lines
 
     return os.terminal_size((columns, lines))
+ 
+ import sys, os, subprocess, errno
+ 
+ class NoAssociatedApplicationError(EnvironmentError):
+     """The OS has no application association for files/directories of the given type."""
+ 
+ # def launch(path):
+ # FIXME: confirm the type of path on the various platforms
+  """Open the given path with the application that the OS associates with the path's file type.
+ 
+ :param path: the path to the file or directory to open
+ :type path: On Windows: :class:`str`. On Unix and Mac OS X: :class:`bytes`.
+ 
+ On Windows, calls :func:`os.startfile`.
+ 
+ On Mac OS X, uses the ```open <https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man1/open.1.html>`_`` command.
+ 
+ On non-Mac Unix, uses the ```xdg-open <http://portland.freedesktop.org/xdg-utils-1.0/xdg-open.html>`_`` command and fails
+ if it can't be run (e.g., when it's not installed).
+ 
+ :raises NotImplementedError: on non-Mac Unix when ``xdg-open`` itself cannot be run
+ :raises FileNotFoundError: when *path* doesn't exist
+ :raises NoAssociatedApplicationError: when the OS has no application association for files/directories of *path*'s type
+ :raises OSError, IOError, subprocess.CalledProcessError: when lower-level implementation APIs encounter errors
+ :returns: None
+ 
+ Availability: Mac OS X, Unix, Windows
+ 
+ Example:
+ >>> launch('README')
+ """
+ 
+ if sys.platform.startswith('win32'):
+     def launch(path):
+         path = os.path.normpath(path) # Ensure cross-platform path (Windows-friendly)
+         os.startfile(path)
+ 
+ elif sys.platform.startswith('darwin'):
+     def launch(path):
+         path = os.path.normpath(path) # Ensure cross-platform path
+         # https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man1/open.1.html
+         cmd = ['open', path]
+         proc = subprocess.Popen(cmd, stderr=subprocess.PIPE,
+                                     stdin=subprocess.DEVNULL,
+                                     stdout=subprocess.DEVNULL)
+         _, stderr_output = proc.communicate()
+         if proc.returncode:
+             if stderr_output.endswith("does not exist."):
+                 raise FileNotFoundError("Path %s may not exist" % repr(path)) from err
+             elif stderr_output.startswith("No application can open"):
+                 raise NoAssociatedApplicationError("No application is associated with files/directories of the given type") from err
+             else:
+                 raise subprocess.CalledProcessError(proc.returncode, cmd, stderr_output)
+ 
+ elif os.name == 'posix':
+     def launch(path):
+         path = os.path.normpath(path) # Ensure cross-platform path
+         # http://portland.freedesktop.org/xdg-utils-1.0/xdg-open.html
+         try:
+             subprocess.check_call(['xdg-open', path],
+                                     stdin=subprocess.DEVNULL,
+                                     stdout=subprocess.DEVNULL,
+                                     stderr=subprocess.DEVNULL)
+         except subprocess.CalledProcessError as err:
+             if err.returncode == 2:
+                 raise FileNotFoundError("Path %s may not exist" % repr(path)) from err
+             elif err.returncode == 3:
+                 raise NoAssociatedApplicationError("No application is associated with files/directories of the given type") from err
+             else:
+                 raise
+         except EnvironmentError as err:
+             if err.errno == errno.ENOENT: # xdg-open not installed/accessible
+                 raise NotImplementedError from err
+             else:
+                 raise
+