Index: Doc/library/os.rst
===================================================================
--- Doc/library/os.rst	(revision 59590)
+++ Doc/library/os.rst	(working copy)
@@ -1007,17 +1007,20 @@
    .. versionadded:: 2.3
 
 
-.. function:: mkdir(path[, mode])
+.. function:: mkdir(path[, mode[, excl=True]])
 
    Create a directory named *path* with numeric mode *mode*. The default *mode* is
    ``0777`` (octal).  On some systems, *mode* is ignored.  Where it is used, the
    current umask value is first masked out. Availability: Macintosh, Unix, Windows.
 
+   By default, if the directory already exists, :exc:`OSError` is thrown.  If excl is
+   False, it is not an error for the directory to exist already.
+
    It is also possible to create temporary directories; see the
    :mod:`tempfile` module's :func:`tempfile.mkdtemp` function.
 
 
-.. function:: makedirs(path[, mode])
+.. function:: makedirs(path[, mode[, excl=True]])
 
    .. index::
       single: directory; creating
@@ -1029,6 +1032,10 @@
    created.  The default *mode* is ``0777`` (octal).  On some systems, *mode* is
    ignored. Where it is used, the current umask value is first masked out.
 
+   By default, if the directory already exists, :exc:`OSError` is thrown.  If
+   excl is False, it is not an error for the directory to exist already.  It
+   is never an error for ancestor directories to exist already.
+
    .. note::
 
       :func:`makedirs` will become confused if the path elements to create include
Index: Lib/os.py
===================================================================
--- Lib/os.py	(revision 59590)
+++ Lib/os.py	(working copy)
@@ -146,29 +146,39 @@
 
 # Super directory utilities.
 # (Inspired by Eric Raymond; the doc strings are mostly his)
+_mkdir = mkdir
 
-def makedirs(name, mode=0777):
-    """makedirs(path [, mode=0777])
+def mkdir(name, mode=0777, excl=True):
+    """mkdir(path [, mode=0777 [, excl=True]])
+    
+    Create the named directory in the indicated mode.  By default, if the
+    directory already exists, OSError is thrown.  If excl is False, it is
+    not an error for the directory to exist already.
+    """
+    try:
+        _mkdir(name, mode)
+    except OSError, e:
+        if excl or not (e.errno == errno.EEXIST and path.isdir (name)):
+            raise
 
+def makedirs(name, mode=0777, excl=True):
+    """makedirs(path [, mode=0777 [, excl=True]])
+
     Super-mkdir; create a leaf directory and all intermediate ones.
     Works like mkdir, except that any intermediate path segment (not
     just the rightmost) will be created if it does not exist.  This is
-    recursive.
-
+    recursive.  By default, if the directory already exists, OSError is
+    thrown.  If excl is False, it is not an error for the directory to exist
+    already.  It is never an error for ancestor directories to exist already.
     """
     head, tail = path.split(name)
     if not tail:
         head, tail = path.split(head)
     if head and tail and not path.exists(head):
-        try:
-            makedirs(head, mode)
-        except OSError, e:
-            # be happy if someone already created the path
-            if e.errno != errno.EEXIST:
-                raise
+        makedirs(head, mode, excl=False)
         if tail == curdir:           # xxx/newdir/. exists if xxx/newdir exists
             return
-    mkdir(name, mode)
+    mkdir(name, mode, excl)
 
 def removedirs(name):
     """removedirs(path)