diff -r 95d1adf144ee Doc/library/os.rst
--- a/Doc/library/os.rst	Sat Nov 03 14:37:37 2012 +0200
+++ b/Doc/library/os.rst	Mon Nov 05 20:52:55 2012 +0200
@@ -2269,6 +2269,15 @@
    .. versionadded:: 3.3
 
 
+.. function :: get_shell()
+
+  Return the path to default shell.
+
+  For unix system returns path to ``sh``, for windows returns path to ``cmd.exe``.
+
+  .. versionadded:: 3.4
+
+
 Linux extended attributes
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff -r 95d1adf144ee Lib/os.py
--- a/Lib/os.py	Sat Nov 03 14:37:37 2012 +0200
+++ b/Lib/os.py	Mon Nov 05 20:52:55 2012 +0200
@@ -1006,3 +1006,30 @@
         raise TypeError("invalid fd type (%s, expected integer)" % type(fd))
     import io
     return io.open(fd, *args, **kwargs)
+
+
+def get_shell():
+    """Return the path to default shell."""
+    if sys.platform == "win32":
+        return _get_shell_for_windows()
+    else:
+        return _get_shell_for_unix()
+
+
+def _get_shell_for_windows():
+    """Return the path to default shell for Windows"""
+    return environ.get("COMSPEC", "cmd.exe")
+
+
+def _get_shell_for_unix():
+    """Return the path to default shell for Unix"""
+    for path in confstr("CS_PATH").split(pathsep):
+        sh = sep.join((path, "sh"))
+        try:
+            mode = stat(sh).st_mode
+        except OSError:
+            pass
+        else:
+            if st.S_ISREG(mode):
+                return sh
+    raise FileNotFound("sh")
diff -r 95d1adf144ee Lib/test/test_os.py
--- a/Lib/test/test_os.py	Sat Nov 03 14:37:37 2012 +0200
+++ b/Lib/test/test_os.py	Mon Nov 05 20:52:55 2012 +0200
@@ -2134,6 +2134,19 @@
                 else:
                     self.fail("No exception thrown by {}".format(func))
 
+
+class TestGetShell(unittest.TestCase):
+    def test_get_shell(self):
+        shell = os.get_shell()
+        param = "/c" if sys.platform == 'win32' else "-c"
+        s = subprocess.Popen([shell, param, "echo test"],
+                                stdout=subprocess.PIPE)
+        stdout, stderr = s.communicate()
+        self.assertIn(b"test", stdout)
+        self.assertIsNone(stderr)
+        self.assertEqual(0, s.returncode)
+
+
 @support.reap_threads
 def test_main():
     support.run_unittest(
@@ -2163,6 +2176,7 @@
         Win32DeprecatedBytesAPI,
         TermsizeTests,
         OSErrorTests,
+        TestGetShell,
     )
 
 if __name__ == "__main__":