Merge branch 'master' of ssh://git.fedoraproject.org/git/hosted/func

* 'master' of ssh://git.fedoraproject.org/git/hosted/func:
  add a basic AuditLogger class
  Package the subprocess module so that we can use it on EL4.
  Basic plugin for checking SMART status on drives.
  Add basic module for checking smart status of drives.
  Remove header from ps output

9 files changed, 1333 insertions, 27 deletions

diff --git a/client/test_func.py b/client/test_func.py
index 6362b85..bcce45d 100644
--- a/client/test_func.py
+++ b/client/test_func.py
@@ -5,10 +5,11 @@
 
 import xmlrpclib
 
-TEST_PROCESS = True
+TEST_PROCESS = False
 TEST_VIRT = False
-TEST_SERVICES = True
-TEST_HARDWARE = True
+TEST_SERVICES = False
+TEST_HARDWARE =  False
+TEST_SMART = True
 
 # get a connecton (to be replaced by client lib logic)
 s = xmlrpclib.ServerProxy("http://127.0.0.1:51234")
@@ -16,9 +17,12 @@ s = xmlrpclib.ServerProxy("http://127.0.0.1:51234")
 # here's the basic test...
 print s.test.add(1, 2)
 
+if TEST_SMART:
+    print s.smart.info()
+
 if TEST_PROCESS:
     print s.process.info()
-    print s.process.pkill("thunderbird")
+    # print s.process.pkill("thunderbird")
 
 # here's the service module testing
 if TEST_SERVICES:
diff --git a/modules/process.py b/modules/process.py
index 064b1b3..3e40fe1 100755
--- a/modules/process.py
+++ b/modules/process.py
@@ -15,7 +15,7 @@
 ##
 
 # other modules
-import subprocess
+import sub_process
 
 # our modules
 from codes import *
@@ -32,7 +32,7 @@ class ProcessModule(func_module.FuncModule):
         }
         func_module.FuncModule.__init__(self)
 
-    def info(self,flags="-aux"):
+    def info(self,flags="-auxh"):
         """
         Returns a struct of hardware information.  By default, this pulls down
         all of the devices.  If you don't care about them, set with_devices to
@@ -41,7 +41,7 @@ class ProcessModule(func_module.FuncModule):
 
         flags.replace(";","") # prevent stupidity
 
-        cmd = subprocess.Popen("ps %s" % flags,stdout=subprocess.PIPE,shell=True)
+        cmd = sub_process.Popen("ps %s" % flags,stdout=sub_process.PIPE,shell=True)
         data = cmd.communicate()[0]
 
         results = []       
@@ -53,12 +53,12 @@ class ProcessModule(func_module.FuncModule):
         return results
 
     def kill(self,pid,level=""):
-        rc = subprocess.call("/bin/kill %s %s" % (pid, level), shell=True)
+        rc = sub_process.call("/bin/kill %s %s" % (pid, level), shell=True)
         return rc
 
     def pkill(self,name,level=""):
         # example killall("thunderbird","-9")
-        rc = subprocess.call("/usr/bin/pkill %s %s" % (name, level), shell=True)
+        rc = sub_process.call("/usr/bin/pkill %s %s" % (name, level), shell=True)
         return rc
 
 methods = ProcessModule()
diff --git a/modules/reboot.py b/modules/reboot.py
index ddc7651..8772b8f 100755
--- a/modules/reboot.py
+++ b/modules/reboot.py
@@ -11,7 +11,7 @@
 
 from modules import func_module
 
-import subprocess
+import sub_process
 
 class Reboot(func_module.FuncModule):
 
@@ -22,7 +22,7 @@ class Reboot(func_module.FuncModule):
         func_module.FuncModule.__init__(self)
 
     def reboot(self, when='now', message=''):
-        return subprocess.call(["/sbin/shutdown", '-r', when, message])
+        return sub_process.call(["/sbin/shutdown", '-r', when, message])
 
 
 methods = Reboot()
diff --git a/modules/service.py b/modules/service.py
index bbc51e1..524cd7b 100755
--- a/modules/service.py
+++ b/modules/service.py
@@ -18,7 +18,7 @@
 from codes import *
 from modules import func_module
 
-import subprocess
+import sub_process
 import os
 
 class Service(func_module.FuncModule):
@@ -37,7 +37,7 @@ class Service(func_module.FuncModule):
 
         filename = os.path.join("/etc/rc.d/init.d/",service_name)
         if os.path.exists(filename):
-            return subprocess.call(["/sbin/service", service_name, command])
+            return sub_process.call(["/sbin/service", service_name, command])
         else:
             raise FuncException("Service not installed: %s" % service_name)
 
diff --git a/modules/smart.py b/modules/smart.py
new file mode 100755
index 0000000..4ed8335
--- /dev/null
+++ b/modules/smart.py
@@ -0,0 +1,57 @@
+#!/usr/bin/python
+
+## 
+## Grabs status from SMART to see if your hard drives are ok
+## Returns in the format of (return code, [line1, line2, line3,...])
+##
+## Copyright 2007, Red Hat, Inc
+## Michael DeHaan <mdehaan@redhat.com>
+##
+## This software may be freely redistributed under the terms of the GNU
+## general public license.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+##
+
+# other modules
+import sub_process
+
+# our modules
+from codes import *
+from modules import func_module
+
+# =================================
+
+class SmartModule(func_module.FuncModule):
+    def __init__(self):
+        self.methods = {
+            "info"    : self.info,
+        }
+        func_module.FuncModule.__init__(self)
+
+    def info(self,flags="-q onecheck"):
+        """
+        Returns a struct of hardware information.  By default, this pulls down
+        all of the devices.  If you don't care about them, set with_devices to
+        False.
+        """
+
+        flags.replace(";","") # prevent stupidity
+
+        cmd = sub_process.Popen("/usr/sbin/smartd %s" % flags,stdout=sub_process.PIPE,shell=True)
+        data = cmd.communicate()[0]
+
+        results = []       
+
+        for x in data.split("\n"):
+            results.append(x)
+
+        return (cmd.returncode, results)
+
+methods = SmartModule()
+register_rpc = methods.register_rpc
+
+
+
diff --git a/modules/virt.py b/modules/virt.py
index d345d75..15be92c 100755
--- a/modules/virt.py
+++ b/modules/virt.py
@@ -22,7 +22,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 # other modules
 import sys
 import os
-import subprocess
+import sub_process
 import libvirt
 
 # our modules
@@ -44,7 +44,7 @@ class FuncLibvirtConnection():
     def __init__(self):
 
 
-        cmd = subprocess.Popen("uname -r", shell=True, stdout=subprocess.PIPE)
+        cmd = sub_process.Popen("uname -r", shell=True, stdout=sub_process.PIPE)
         output = cmd.communicate()[0]
 
         if output.find("xen") != -1:
@@ -188,7 +188,7 @@ class Virt(func_module.FuncModule):
             "--server=%s" % server_name
         ]
 
-        rc = subprocess.call(koan_args,shell=False)
+        rc = sub_process.call(koan_args,shell=False)
         if rc == 0:
             return 0
         else:
diff --git a/server/logger.py b/server/logger.py
index fa56a3a..1e60dc0 100755
--- a/server/logger.py
+++ b/server/logger.py
@@ -30,7 +30,7 @@ class Singleton(object):
 # so make sure we do that mess only once
 
 class Logger(Singleton):
-    __no_handlers = True
+    _no_handlers = True
 
     def __init__(self, logfilepath ="/var/log/func/func.log"):
 
@@ -39,18 +39,34 @@ class Logger(Singleton):
            self.loglevel = logging._levelNames[self.config["log_level"]]
         else:
            self.loglevel = logging.INFO   
-        self.__setup_logging()
-        if self.__no_handlers:
-            self.__setup_handlers(logfilepath=logfilepath)
+        self._setup_logging()
+        if self._no_handlers:
+            self._setup_handlers(logfilepath=logfilepath)
         
-    def __setup_logging(self):
+    def _setup_logging(self):
         self.logger = logging.getLogger("svc")
 
-    def __setup_handlers(self, logfilepath="/var/log/func/func.log"):
+    def _setup_handlers(self, logfilepath="/var/log/func/func.log"):
         handler = logging.FileHandler(logfilepath, "a")
         self.logger.setLevel(self.loglevel)
         formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s")
         handler.setFormatter(formatter)
         self.logger.addHandler(handler)
-        self.__no_handlers = False
+        self._no_handlers = False
 
+
+class AuditLogger(Logger):
+    def __init__(self, logfilepath = "/var/log/func/audit.log"):
+        self.loglevel = logging.INFO
+        self._setup_logging()
+        if self._no_handlers:
+             self._setup_handlers(logfilepath=logfilepath)
+
+    def log_call(self, method, params):
+        # square away a good parseable format at some point -akl
+        self.logger.info("%s called with %s" % (method, params))
+
+
+
+
+        
diff --git a/server/server.py b/server/server.py
index bfdf5a9..73ef114 100755
--- a/server/server.py
+++ b/server/server.py
@@ -35,7 +35,7 @@ import utils
 
 class XmlRpcInterface(object):
 
-    def __init__(self, modules={}):
+    def __init__(self, modules={}, server=None):
 
         """
         Constructor.
@@ -45,7 +45,11 @@ class XmlRpcInterface(object):
         self.config = config_obj.get()
         self.modules = modules
         self.logger = logger.Logger().logger
+        self.audit_logger = logger.AuditLogger()
         self.__setup_handlers()
+
+        # need a reference so we can log ip's, certs, etc
+        self.server = server
         
     def __setup_handlers(self):
 
@@ -93,6 +97,10 @@ class XmlRpcInterface(object):
         if method == 'trait_names' or method == '_getAttributeNames':
             return self.handlers.keys()
 
+        # XXX FIXME - need to figure out how to dig into the server base classes
+        # so we can get client ip, and eventually cert id info -akl
+        self.audit_logger.log_call(method, params)
+
         return self.get_dispatch_method(method)(*params)
 
 # ======================================================================================
@@ -139,15 +147,20 @@ class FuncApiMethod:
 
 # ======================================================================================
 
-def serve(websvc):
+def serve():
 
      """
      Code for starting the XMLRPC service. 
      FIXME:  make this HTTPS (see RRS code) and make accompanying Rails changes..
      """
 
+     modules = module_loader.load_modules()
+
      server =FuncXMLRPCServer(('', 51234))
      server.logRequests = 0 # don't print stuff to console
+
+     websvc = XmlRpcInterface(modules=modules,server=server)
+     
      server.register_instance(websvc)
      server.serve_forever()
 
@@ -184,7 +197,7 @@ def main(argv):
     print "Seriously.\n\n"
 
     try:
-        websvc = XmlRpcInterface(modules=modules)
+        serve()
     except codes.FuncException, e:
         print >> sys.stderr, 'error: %s' % e
         sys.exit(1)
@@ -194,7 +207,6 @@ def main(argv):
     else:
         print "serving...\n"
 
-    serve(websvc)
        
 # ======================================================================================
 
diff --git a/server/sub_process.py b/server/sub_process.py
new file mode 100644
index 0000000..7c229dc
--- /dev/null
+++ b/server/sub_process.py
@@ -0,0 +1,1217 @@
+# subprocess - Subprocesses with accessible I/O streams
+#
+# For more information about this module, see PEP 324.
+#
+# This module should remain compatible with Python 2.2, see PEP 291.
+#
+# Copyright (c) 2003-2005 by Peter Astrand <astrand@lysator.liu.se>
+#
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/2.4/license for licensing details.
+
+r"""subprocess - Subprocesses with accessible I/O streams
+
+This module allows you to spawn processes, connect to their
+input/output/error pipes, and obtain their return codes.  This module
+intends to replace several other, older modules and functions, like:
+
+os.system
+os.spawn*
+os.popen*
+popen2.*
+commands.*
+
+Information about how the subprocess module can be used to replace these
+modules and functions can be found below.
+
+
+
+Using the subprocess module
+===========================
+This module defines one class called Popen:
+
+class Popen(args, bufsize=0, executable=None,
+            stdin=None, stdout=None, stderr=None,
+            preexec_fn=None, close_fds=False, shell=False,
+            cwd=None, env=None, universal_newlines=False,
+            startupinfo=None, creationflags=0):
+
+
+Arguments are:
+
+args should be a string, or a sequence of program arguments.  The
+program to execute is normally the first item in the args sequence or
+string, but can be explicitly set by using the executable argument.
+
+On UNIX, with shell=False (default): In this case, the Popen class
+uses os.execvp() to execute the child program.  args should normally
+be a sequence.  A string will be treated as a sequence with the string
+as the only item (the program to execute).
+
+On UNIX, with shell=True: If args is a string, it specifies the
+command string to execute through the shell.  If args is a sequence,
+the first item specifies the command string, and any additional items
+will be treated as additional shell arguments.
+
+On Windows: the Popen class uses CreateProcess() to execute the child
+program, which operates on strings.  If args is a sequence, it will be
+converted to a string using the list2cmdline method.  Please note that
+not all MS Windows applications interpret the command line the same
+way: The list2cmdline is designed for applications using the same
+rules as the MS C runtime.
+
+bufsize, if given, has the same meaning as the corresponding argument
+to the built-in open() function: 0 means unbuffered, 1 means line
+buffered, any other positive value means use a buffer of
+(approximately) that size.  A negative bufsize means to use the system
+default, which usually means fully buffered.  The default value for
+bufsize is 0 (unbuffered).
+
+stdin, stdout and stderr specify the executed programs' standard
+input, standard output and standard error file handles, respectively.
+Valid values are PIPE, an existing file descriptor (a positive
+integer), an existing file object, and None.  PIPE indicates that a
+new pipe to the child should be created.  With None, no redirection
+will occur; the child's file handles will be inherited from the
+parent.  Additionally, stderr can be STDOUT, which indicates that the
+stderr data from the applications should be captured into the same
+file handle as for stdout.
+
+If preexec_fn is set to a callable object, this object will be called
+in the child process just before the child is executed.
+
+If close_fds is true, all file descriptors except 0, 1 and 2 will be
+closed before the child process is executed.
+
+if shell is true, the specified command will be executed through the
+shell.
+
+If cwd is not None, the current directory will be changed to cwd
+before the child is executed.
+
+If env is not None, it defines the environment variables for the new
+process.
+
+If universal_newlines is true, the file objects stdout and stderr are
+opened as a text files, but lines may be terminated by any of '\n',
+the Unix end-of-line convention, '\r', the Macintosh convention or
+'\r\n', the Windows convention.  All of these external representations
+are seen as '\n' by the Python program.  Note: This feature is only
+available if Python is built with universal newline support (the
+default).  Also, the newlines attribute of the file objects stdout,
+stdin and stderr are not updated by the communicate() method.
+
+The startupinfo and creationflags, if given, will be passed to the
+underlying CreateProcess() function.  They can specify things such as
+appearance of the main window and priority for the new process.
+(Windows only)
+
+
+This module also defines two shortcut functions:
+
+call(*popenargs, **kwargs):
+    Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+
+check_call(*popenargs, **kwargs):
+    Run command with arguments.  Wait for command to complete.  If the
+    exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+
+Exceptions
+----------
+Exceptions raised in the child process, before the new program has
+started to execute, will be re-raised in the parent.  Additionally,
+the exception object will have one extra attribute called
+'child_traceback', which is a string containing traceback information
+from the childs point of view.
+
+The most common exception raised is OSError.  This occurs, for
+example, when trying to execute a non-existent file.  Applications
+should prepare for OSErrors.
+
+A ValueError will be raised if Popen is called with invalid arguments.
+
+check_call() will raise CalledProcessError, if the called process
+returns a non-zero return code.
+
+
+Security
+--------
+Unlike some other popen functions, this implementation will never call
+/bin/sh implicitly.  This means that all characters, including shell
+metacharacters, can safely be passed to child processes.
+
+
+Popen objects
+=============
+Instances of the Popen class have the following methods:
+
+poll()
+    Check if child process has terminated.  Returns returncode
+    attribute.
+
+wait()
+    Wait for child process to terminate.  Returns returncode attribute.
+
+communicate(input=None)
+    Interact with process: Send data to stdin.  Read data from stdout
+    and stderr, until end-of-file is reached.  Wait for process to
+    terminate.  The optional stdin argument should be a string to be
+    sent to the child process, or None, if no data should be sent to
+    the child.
+
+    communicate() returns a tuple (stdout, stderr).
+
+    Note: The data read is buffered in memory, so do not use this
+    method if the data size is large or unlimited.
+
+The following attributes are also available:
+
+stdin
+    If the stdin argument is PIPE, this attribute is a file object
+    that provides input to the child process.  Otherwise, it is None.
+
+stdout
+    If the stdout argument is PIPE, this attribute is a file object
+    that provides output from the child process.  Otherwise, it is
+    None.
+
+stderr
+    If the stderr argument is PIPE, this attribute is file object that
+    provides error output from the child process.  Otherwise, it is
+    None.
+
+pid
+    The process ID of the child process.
+
+returncode
+    The child return code.  A None value indicates that the process
+    hasn't terminated yet.  A negative value -N indicates that the
+    child was terminated by signal N (UNIX only).
+
+
+Replacing older functions with the subprocess module
+====================================================
+In this section, "a ==> b" means that b can be used as a replacement
+for a.
+
+Note: All functions in this section fail (more or less) silently if
+the executed program cannot be found; this module raises an OSError
+exception.
+
+In the following examples, we assume that the subprocess module is
+imported with "from subprocess import *".
+
+
+Replacing /bin/sh shell backquote
+---------------------------------
+output=`mycmd myarg`
+==>
+output = Popen(["mycmd", "myarg"], stdout=PIPE).communicate()[0]
+
+
+Replacing shell pipe line
+-------------------------
+output=`dmesg | grep hda`
+==>
+p1 = Popen(["dmesg"], stdout=PIPE)
+p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
+output = p2.communicate()[0]
+
+
+Replacing os.system()
+---------------------
+sts = os.system("mycmd" + " myarg")
+==>
+p = Popen("mycmd" + " myarg", shell=True)
+pid, sts = os.waitpid(p.pid, 0)
+
+Note:
+
+* Calling the program through the shell is usually not required.
+
+* It's easier to look at the returncode attribute than the
+  exitstatus.
+
+A more real-world example would look like this:
+
+try:
+    retcode = call("mycmd" + " myarg", shell=True)
+    if retcode < 0:
+        print >>sys.stderr, "Child was terminated by signal", -retcode
+    else:
+        print >>sys.stderr, "Child returned", retcode
+except OSError, e:
+    print >>sys.stderr, "Execution failed:", e
+
+
+Replacing os.spawn*
+-------------------
+P_NOWAIT example:
+
+pid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")
+==>
+pid = Popen(["/bin/mycmd", "myarg"]).pid
+
+
+P_WAIT example:
+
+retcode = os.spawnlp(os.P_WAIT, "/bin/mycmd", "mycmd", "myarg")
+==>
+retcode = call(["/bin/mycmd", "myarg"])
+
+
+Vector example:
+
+os.spawnvp(os.P_NOWAIT, path, args)
+==>
+Popen([path] + args[1:])
+
+
+Environment example:
+
+os.spawnlpe(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg", env)
+==>
+Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
+
+
+Replacing os.popen*
+-------------------
+pipe = os.popen(cmd, mode='r', bufsize)
+==>
+pipe = Popen(cmd, shell=True, bufsize=bufsize, stdout=PIPE).stdout
+
+pipe = os.popen(cmd, mode='w', bufsize)
+==>
+pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin
+
+
+(child_stdin, child_stdout) = os.popen2(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdin, child_stdout) = (p.stdin, p.stdout)
+
+
+(child_stdin,
+ child_stdout,
+ child_stderr) = os.popen3(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, stderr=PIPE, close_fds=True)
+(child_stdin,
+ child_stdout,
+ child_stderr) = (p.stdin, p.stdout, p.stderr)
+
+
+(child_stdin, child_stdout_and_stderr) = os.popen4(cmd, mode, bufsize)
+==>
+p = Popen(cmd, shell=True, bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, stderr=STDOUT, close_fds=True)
+(child_stdin, child_stdout_and_stderr) = (p.stdin, p.stdout)
+
+
+Replacing popen2.*
+------------------
+Note: If the cmd argument to popen2 functions is a string, the command
+is executed through /bin/sh.  If it is a list, the command is directly
+executed.
+
+(child_stdout, child_stdin) = popen2.popen2("somestring", bufsize, mode)
+==>
+p = Popen(["somestring"], shell=True, bufsize=bufsize
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdout, child_stdin) = (p.stdout, p.stdin)
+
+
+(child_stdout, child_stdin) = popen2.popen2(["mycmd", "myarg"], bufsize, mode)
+==>
+p = Popen(["mycmd", "myarg"], bufsize=bufsize,
+          stdin=PIPE, stdout=PIPE, close_fds=True)
+(child_stdout, child_stdin) = (p.stdout, p.stdin)
+
+The popen2.Popen3 and popen3.Popen4 basically works as subprocess.Popen,
+except that:
+
+* subprocess.Popen raises an exception if the execution fails
+* the capturestderr argument is replaced with the stderr argument.
+* stdin=PIPE and stdout=PIPE must be specified.
+* popen2 closes all filedescriptors by default, but you have to specify
+  close_fds=True with subprocess.Popen.
+
+
+"""
+
+import sys
+mswindows = (sys.platform == "win32")
+
+import os
+import types
+import traceback
+
+# Exception classes used by this module.
+class CalledProcessError(Exception):
+    """This exception is raised when a process run by check_call() returns
+    a non-zero exit status.  The exit status will be stored in the
+    returncode attribute."""
+    def __init__(self, returncode, cmd):
+        self.returncode = returncode
+        self.cmd = cmd
+    def __str__(self):
+        return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+
+
+if mswindows:
+    import threading
+    import msvcrt
+    if 0: # <-- change this to use pywin32 instead of the _subprocess driver
+        import pywintypes
+        from win32api import GetStdHandle, STD_INPUT_HANDLE, \
+                             STD_OUTPUT_HANDLE, STD_ERROR_HANDLE
+        from win32api import GetCurrentProcess, DuplicateHandle, \
+                             GetModuleFileName, GetVersion
+        from win32con import DUPLICATE_SAME_ACCESS, SW_HIDE
+        from win32pipe import CreatePipe
+        from win32process import CreateProcess, STARTUPINFO, \
+                                 GetExitCodeProcess, STARTF_USESTDHANDLES, \
+                                 STARTF_USESHOWWINDOW, CREATE_NEW_CONSOLE
+        from win32event import WaitForSingleObject, INFINITE, WAIT_OBJECT_0
+    else:
+        from _subprocess import *
+        class STARTUPINFO:
+            dwFlags = 0
+            hStdInput = None
+            hStdOutput = None
+            hStdError = None
+            wShowWindow = 0
+        class pywintypes:
+            error = IOError
+else:
+    import select
+    import errno
+    import fcntl
+    import pickle
+
+__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "CalledProcessError"]
+
+try:
+    MAXFD = os.sysconf("SC_OPEN_MAX")
+except:
+    MAXFD = 256
+
+# True/False does not exist on 2.2.0
+try:
+    False
+except NameError:
+    False = 0
+    True = 1
+
+_active = []
+
+def _cleanup():
+    for inst in _active[:]:
+        if inst.poll(_deadstate=sys.maxint) >= 0:
+            try:
+                _active.remove(inst)
+            except ValueError:
+                # This can happen if two threads create a new Popen instance.
+                # It's harmless that it was already removed, so ignore.
+                pass
+
+PIPE = -1
+STDOUT = -2
+
+
+def call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+    """
+    return Popen(*popenargs, **kwargs).wait()
+
+
+def check_call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete.  If
+    the exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+    """
+    retcode = call(*popenargs, **kwargs)
+    cmd = kwargs.get("args")
+    if cmd is None:
+        cmd = popenargs[0]
+    if retcode:
+        raise CalledProcessError(retcode, cmd)
+    return retcode
+
+
+def list2cmdline(seq):
+    """
+    Translate a sequence of arguments into a command line
+    string, using the same rules as the MS C runtime:
+
+    1) Arguments are delimited by white space, which is either a
+       space or a tab.
+
+    2) A string surrounded by double quotation marks is
+       interpreted as a single argument, regardless of white space
+       contained within.  A quoted string can be embedded in an
+       argument.
+
+    3) A double quotation mark preceded by a backslash is
+       interpreted as a literal double quotation mark.
+
+    4) Backslashes are interpreted literally, unless they
+       immediately precede a double quotation mark.
+
+    5) If backslashes immediately precede a double quotation mark,
+       every pair of backslashes is interpreted as a literal
+       backslash.  If the number of backslashes is odd, the last
+       backslash escapes the next double quotation mark as
+       described in rule 3.
+    """
+
+    # See
+    # http://msdn.microsoft.com/library/en-us/vccelng/htm/progs_12.asp
+    result = []
+    needquote = False
+    for arg in seq:
+        bs_buf = []
+
+        # Add a space to separate this argument from the others
+        if result:
+            result.append(' ')
+
+        needquote = (" " in arg) or ("\t" in arg)
+        if needquote:
+            result.append('"')
+
+        for c in arg:
+            if c == '\\':
+                # Don't know if we need to double yet.
+                bs_buf.append(c)
+            elif c == '"':
+                # Double backspaces.
+                result.append('\\' * len(bs_buf)*2)
+                bs_buf = []
+                result.append('\\"')
+            else:
+                # Normal char
+                if bs_buf:
+                    result.extend(bs_buf)
+                    bs_buf = []
+                result.append(c)
+
+        # Add remaining backspaces, if any.
+        if bs_buf:
+            result.extend(bs_buf)
+
+        if needquote:
+            result.extend(bs_buf)
+            result.append('"')
+
+    return ''.join(result)
+
+
+class Popen(object):
+    def __init__(self, args, bufsize=0, executable=None,
+                 stdin=None, stdout=None, stderr=None,
+                 preexec_fn=None, close_fds=False, shell=False,
+                 cwd=None, env=None, universal_newlines=False,
+                 startupinfo=None, creationflags=0):
+        """Create new Popen instance."""
+        _cleanup()
+
+        self._child_created = False
+        if not isinstance(bufsize, (int, long)):
+            raise TypeError("bufsize must be an integer")
+
+        if mswindows:
+            if preexec_fn is not None:
+                raise ValueError("preexec_fn is not supported on Windows "
+                                 "platforms")
+            if close_fds:
+                raise ValueError("close_fds is not supported on Windows "
+                                 "platforms")
+        else:
+            # POSIX
+            if startupinfo is not None:
+                raise ValueError("startupinfo is only supported on Windows "
+                                 "platforms")
+            if creationflags != 0:
+                raise ValueError("creationflags is only supported on Windows "
+                                 "platforms")
+
+        self.stdin = None
+        self.stdout = None
+        self.stderr = None
+        self.pid = None
+        self.returncode = None
+        self.universal_newlines = universal_newlines
+
+        # Input and output objects. The general principle is like
+        # this:
+        #
+        # Parent                   Child
+        # ------                   -----
+        # p2cwrite   ---stdin--->  p2cread
+        # c2pread    <--stdout---  c2pwrite
+        # errread    <--stderr---  errwrite
+        #
+        # On POSIX, the child objects are file descriptors.  On
+        # Windows, these are Windows file handles.  The parent objects
+        # are file descriptors on both platforms.  The parent objects
+        # are None when not using PIPEs. The child objects are None
+        # when not redirecting.
+
+        (p2cread, p2cwrite,
+         c2pread, c2pwrite,
+         errread, errwrite) = self._get_handles(stdin, stdout, stderr)
+
+        self._execute_child(args, executable, preexec_fn, close_fds,
+                            cwd, env, universal_newlines,
+                            startupinfo, creationflags, shell,
+                            p2cread, p2cwrite,
+                            c2pread, c2pwrite,
+                            errread, errwrite)
+
+        if p2cwrite:
+            self.stdin = os.fdopen(p2cwrite, 'wb', bufsize)
+        if c2pread:
+            if universal_newlines:
+                self.stdout = os.fdopen(c2pread, 'rU', bufsize)
+            else:
+                self.stdout = os.fdopen(c2pread, 'rb', bufsize)
+        if errread:
+            if universal_newlines:
+                self.stderr = os.fdopen(errread, 'rU', bufsize)
+            else:
+                self.stderr = os.fdopen(errread, 'rb', bufsize)
+
+
+    def _translate_newlines(self, data):
+        data = data.replace("\r\n", "\n")
+        data = data.replace("\r", "\n")
+        return data
+
+
+    def __del__(self):
+        if not self._child_created:
+            # We didn't get to successfully create a child process.
+            return
+        # In case the child hasn't been waited on, check if it's done.
+        self.poll(_deadstate=sys.maxint)
+        if self.returncode is None and _active is not None:
+            # Child is still running, keep us alive until we can wait on it.
+            _active.append(self)
+
+
+    def communicate(self, input=None):
+        """Interact with process: Send data to stdin.  Read data from
+        stdout and stderr, until end-of-file is reached.  Wait for
+        process to terminate.  The optional input argument should be a
+        string to be sent to the child process, or None, if no data
+        should be sent to the child.
+
+        communicate() returns a tuple (stdout, stderr)."""
+
+        # Optimization: If we are only using one pipe, or no pipe at
+        # all, using select() or threads is unnecessary.
+        if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
+            stdout = None
+            stderr = None
+            if self.stdin:
+                if input:
+                    self.stdin.write(input)
+                self.stdin.close()
+            elif self.stdout:
+                stdout = self.stdout.read()
+            elif self.stderr:
+                stderr = self.stderr.read()
+            self.wait()
+            return (stdout, stderr)
+
+        return self._communicate(input)
+
+
+    if mswindows:
+        #
+        # Windows methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tupel with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            if stdin is None and stdout is None and stderr is None:
+                return (None, None, None, None, None, None)
+
+            p2cread, p2cwrite = None, None
+            c2pread, c2pwrite = None, None
+            errread, errwrite = None, None
+
+            if stdin is None:
+                p2cread = GetStdHandle(STD_INPUT_HANDLE)
+            elif stdin == PIPE:
+                p2cread, p2cwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                p2cwrite = p2cwrite.Detach()
+                p2cwrite = msvcrt.open_osfhandle(p2cwrite, 0)
+            elif isinstance(stdin, int):
+                p2cread = msvcrt.get_osfhandle(stdin)
+            else:
+                # Assuming file-like object
+                p2cread = msvcrt.get_osfhandle(stdin.fileno())
+            p2cread = self._make_inheritable(p2cread)
+
+            if stdout is None:
+                c2pwrite = GetStdHandle(STD_OUTPUT_HANDLE)
+            elif stdout == PIPE:
+                c2pread, c2pwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                c2pread = c2pread.Detach()
+                c2pread = msvcrt.open_osfhandle(c2pread, 0)
+            elif isinstance(stdout, int):
+                c2pwrite = msvcrt.get_osfhandle(stdout)
+            else:
+                # Assuming file-like object
+                c2pwrite = msvcrt.get_osfhandle(stdout.fileno())
+            c2pwrite = self._make_inheritable(c2pwrite)
+
+            if stderr is None:
+                errwrite = GetStdHandle(STD_ERROR_HANDLE)
+            elif stderr == PIPE:
+                errread, errwrite = CreatePipe(None, 0)
+                # Detach and turn into fd
+                errread = errread.Detach()
+                errread = msvcrt.open_osfhandle(errread, 0)
+            elif stderr == STDOUT:
+                errwrite = c2pwrite
+            elif isinstance(stderr, int):
+                errwrite = msvcrt.get_osfhandle(stderr)
+            else:
+                # Assuming file-like object
+                errwrite = msvcrt.get_osfhandle(stderr.fileno())
+            errwrite = self._make_inheritable(errwrite)
+
+            return (p2cread, p2cwrite,
+                    c2pread, c2pwrite,
+                    errread, errwrite)
+
+
+        def _make_inheritable(self, handle):
+            """Return a duplicate of handle, which is inheritable"""
+            return DuplicateHandle(GetCurrentProcess(), handle,
+                                   GetCurrentProcess(), 0, 1,
+                                   DUPLICATE_SAME_ACCESS)
+
+
+        def _find_w9xpopen(self):
+            """Find and return absolut path to w9xpopen.exe"""
+            w9xpopen = os.path.join(os.path.dirname(GetModuleFileName(0)),
+                                    "w9xpopen.exe")
+            if not os.path.exists(w9xpopen):
+                # Eeek - file-not-found - possibly an embedding
+                # situation - see if we can locate it in sys.exec_prefix
+                w9xpopen = os.path.join(os.path.dirname(sys.exec_prefix),
+                                        "w9xpopen.exe")
+                if not os.path.exists(w9xpopen):
+                    raise RuntimeError("Cannot locate w9xpopen.exe, which is "
+                                       "needed for Popen to work with your "
+                                       "shell or platform.")
+            return w9xpopen
+
+
+        def _execute_child(self, args, executable, preexec_fn, close_fds,
+                           cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite):
+            """Execute program (MS Windows version)"""
+
+            if not isinstance(args, types.StringTypes):
+                args = list2cmdline(args)
+
+            # Process startup details
+            if startupinfo is None:
+                startupinfo = STARTUPINFO()
+            if None not in (p2cread, c2pwrite, errwrite):
+                startupinfo.dwFlags |= STARTF_USESTDHANDLES
+                startupinfo.hStdInput = p2cread
+                startupinfo.hStdOutput = c2pwrite
+                startupinfo.hStdError = errwrite
+
+            if shell:
+                startupinfo.dwFlags |= STARTF_USESHOWWINDOW
+                startupinfo.wShowWindow = SW_HIDE
+                comspec = os.environ.get("COMSPEC", "cmd.exe")
+                args = comspec + " /c " + args
+                if (GetVersion() >= 0x80000000L or
+                        os.path.basename(comspec).lower() == "command.com"):
+                    # Win9x, or using command.com on NT. We need to
+                    # use the w9xpopen intermediate program. For more
+                    # information, see KB Q150956
+                    # (http://web.archive.org/web/20011105084002/http://support.microsoft.com/support/kb/articles/Q150/9/56.asp)
+                    w9xpopen = self._find_w9xpopen()
+                    args = '"%s" %s' % (w9xpopen, args)
+                    # Not passing CREATE_NEW_CONSOLE has been known to
+                    # cause random failures on win9x.  Specifically a
+                    # dialog: "Your program accessed mem currently in
+                    # use at xxx" and a hopeful warning about the
+                    # stability of your system.  Cost is Ctrl+C wont
+                    # kill children.
+                    creationflags |= CREATE_NEW_CONSOLE
+
+            # Start the process
+            try:
+                hp, ht, pid, tid = CreateProcess(executable, args,
+                                         # no special security
+                                         None, None,
+                                         # must inherit handles to pass std
+                                         # handles
+                                         1,
+                                         creationflags,
+                                         env,
+                                         cwd,
+                                         startupinfo)
+            except pywintypes.error, e:
+                # Translate pywintypes.error to WindowsError, which is
+                # a subclass of OSError.  FIXME: We should really
+                # translate errno using _sys_errlist (or simliar), but
+                # how can this be done from Python?
+                raise WindowsError(*e.args)
+
+            # Retain the process handle, but close the thread handle
+            self._child_created = True
+            self._handle = hp
+            self.pid = pid
+            ht.Close()
+
+            # Child is launched. Close the parent's copy of those pipe
+            # handles that only the child should have open.  You need
+            # to make sure that no handles to the write end of the
+            # output pipe are maintained in this process or else the
+            # pipe will not close when the child process exits and the
+            # ReadFile will hang.
+            if p2cread is not None:
+                p2cread.Close()
+            if c2pwrite is not None:
+                c2pwrite.Close()
+            if errwrite is not None:
+                errwrite.Close()
+
+
+        def poll(self, _deadstate=None):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                if WaitForSingleObject(self._handle, 0) == WAIT_OBJECT_0:
+                    self.returncode = GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                obj = WaitForSingleObject(self._handle, INFINITE)
+                self.returncode = GetExitCodeProcess(self._handle)
+            return self.returncode
+
+
+        def _readerthread(self, fh, buffer):
+            buffer.append(fh.read())
+
+
+        def _communicate(self, input):
+            stdout = None # Return
+            stderr = None # Return
+
+            if self.stdout:
+                stdout = []
+                stdout_thread = threading.Thread(target=self._readerthread,
+                                                 args=(self.stdout, stdout))
+                stdout_thread.setDaemon(True)
+                stdout_thread.start()
+            if self.stderr:
+                stderr = []
+                stderr_thread = threading.Thread(target=self._readerthread,
+                                                 args=(self.stderr, stderr))
+                stderr_thread.setDaemon(True)
+                stderr_thread.start()
+
+            if self.stdin:
+                if input is not None:
+                    self.stdin.write(input)
+                self.stdin.close()
+
+            if self.stdout:
+                stdout_thread.join()
+            if self.stderr:
+                stderr_thread.join()
+
+            # All data exchanged.  Translate lists into strings.
+            if stdout is not None:
+                stdout = stdout[0]
+            if stderr is not None:
+                stderr = stderr[0]
+
+            # Translate newlines, if requested.  We cannot let the file
+            # object do the translation: It is based on stdio, which is
+            # impossible to combine with select (unless forcing no
+            # buffering).
+            if self.universal_newlines and hasattr(file, 'newlines'):
+                if stdout:
+                    stdout = self._translate_newlines(stdout)
+                if stderr:
+                    stderr = self._translate_newlines(stderr)
+
+            self.wait()
+            return (stdout, stderr)
+
+    else:
+        #
+        # POSIX methods
+        #
+        def _get_handles(self, stdin, stdout, stderr):
+            """Construct and return tupel with IO objects:
+            p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite
+            """
+            p2cread, p2cwrite = None, None
+            c2pread, c2pwrite = None, None
+            errread, errwrite = None, None
+
+            if stdin is None:
+                pass
+            elif stdin == PIPE:
+                p2cread, p2cwrite = os.pipe()
+            elif isinstance(stdin, int):
+                p2cread = stdin
+            else:
+                # Assuming file-like object
+                p2cread = stdin.fileno()
+
+            if stdout is None:
+                pass
+            elif stdout == PIPE:
+                c2pread, c2pwrite = os.pipe()
+            elif isinstance(stdout, int):
+                c2pwrite = stdout
+            else:
+                # Assuming file-like object
+                c2pwrite = stdout.fileno()
+
+            if stderr is None:
+                pass
+            elif stderr == PIPE:
+                errread, errwrite = os.pipe()
+            elif stderr == STDOUT:
+                errwrite = c2pwrite
+            elif isinstance(stderr, int):
+                errwrite = stderr
+            else:
+                # Assuming file-like object
+                errwrite = stderr.fileno()
+
+            return (p2cread, p2cwrite,
+                    c2pread, c2pwrite,
+                    errread, errwrite)
+
+
+        def _set_cloexec_flag(self, fd):
+            try:
+                cloexec_flag = fcntl.FD_CLOEXEC
+            except AttributeError:
+                cloexec_flag = 1
+
+            old = fcntl.fcntl(fd, fcntl.F_GETFD)
+            fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag)
+
+
+        def _close_fds(self, but):
+            for i in xrange(3, MAXFD):
+                if i == but:
+                    continue
+                try:
+                    os.close(i)
+                except:
+                    pass
+
+
+        def _execute_child(self, args, executable, preexec_fn, close_fds,
+                           cwd, env, universal_newlines,
+                           startupinfo, creationflags, shell,
+                           p2cread, p2cwrite,
+                           c2pread, c2pwrite,
+                           errread, errwrite):
+            """Execute program (POSIX version)"""
+
+            if isinstance(args, types.StringTypes):
+                args = [args]
+
+            if shell:
+                args = ["/bin/sh", "-c"] + args
+
+            if executable is None:
+                executable = args[0]
+
+            # For transferring possible exec failure from child to parent
+            # The first char specifies the exception type: 0 means
+            # OSError, 1 means some other error.
+            errpipe_read, errpipe_write = os.pipe()
+            self._set_cloexec_flag(errpipe_write)
+
+            self.pid = os.fork()
+            self._child_created = True
+            if self.pid == 0:
+                # Child
+                try:
+                    # Close parent's pipe ends
+                    if p2cwrite:
+                        os.close(p2cwrite)
+                    if c2pread:
+                        os.close(c2pread)
+                    if errread:
+                        os.close(errread)
+                    os.close(errpipe_read)
+
+                    # Dup fds for child
+                    if p2cread:
+                        os.dup2(p2cread, 0)
+                    if c2pwrite:
+                        os.dup2(c2pwrite, 1)
+                    if errwrite:
+                        os.dup2(errwrite, 2)
+
+                    # Close pipe fds.  Make sure we don't close the same
+                    # fd more than once, or standard fds.
+                    for fd in set((p2cread, c2pwrite, errwrite))-set((0,1,2)):
+                        if fd: os.close(fd)
+
+                    # Close all other fds, if asked for
+                    if close_fds:
+                        self._close_fds(but=errpipe_write)
+
+                    if cwd is not None:
+                        os.chdir(cwd)
+
+                    if preexec_fn:
+                        apply(preexec_fn)
+
+                    if env is None:
+                        os.execvp(executable, args)
+                    else:
+                        os.execvpe(executable, args, env)
+
+                except:
+                    exc_type, exc_value, tb = sys.exc_info()
+                    # Save the traceback and attach it to the exception object
+                    exc_lines = traceback.format_exception(exc_type,
+                                                           exc_value,
+                                                           tb)
+                    exc_value.child_traceback = ''.join(exc_lines)
+                    os.write(errpipe_write, pickle.dumps(exc_value))
+
+                # This exitcode won't be reported to applications, so it
+                # really doesn't matter what we return.
+                os._exit(255)
+
+            # Parent
+            os.close(errpipe_write)
+            if p2cread and p2cwrite:
+                os.close(p2cread)
+            if c2pwrite and c2pread:
+                os.close(c2pwrite)
+            if errwrite and errread:
+                os.close(errwrite)
+
+            # Wait for exec to fail or succeed; possibly raising exception
+            data = os.read(errpipe_read, 1048576) # Exceptions limited to 1 MB
+            os.close(errpipe_read)
+            if data != "":
+                os.waitpid(self.pid, 0)
+                child_exception = pickle.loads(data)
+                raise child_exception
+
+
+        def _handle_exitstatus(self, sts):
+            if os.WIFSIGNALED(sts):
+                self.returncode = -os.WTERMSIG(sts)
+            elif os.WIFEXITED(sts):
+                self.returncode = os.WEXITSTATUS(sts)
+            else:
+                # Should never happen
+                raise RuntimeError("Unknown child exit status!")
+
+
+        def poll(self, _deadstate=None):
+            """Check if child process has terminated.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                try:
+                    pid, sts = os.waitpid(self.pid, os.WNOHANG)
+                    if pid == self.pid:
+                        self._handle_exitstatus(sts)
+                except os.error:
+                    if _deadstate is not None:
+                        self.returncode = _deadstate
+            return self.returncode
+
+
+        def wait(self):
+            """Wait for child process to terminate.  Returns returncode
+            attribute."""
+            if self.returncode is None:
+                pid, sts = os.waitpid(self.pid, 0)
+                self._handle_exitstatus(sts)
+            return self.returncode
+
+
+        def _communicate(self, input):
+            read_set = []
+            write_set = []
+            stdout = None # Return
+            stderr = None # Return
+
+            if self.stdin:
+                # Flush stdio buffer.  This might block, if the user has
+                # been writing to .stdin in an uncontrolled fashion.
+                self.stdin.flush()
+                if input:
+                    write_set.append(self.stdin)
+                else:
+                    self.stdin.close()
+            if self.stdout:
+                read_set.append(self.stdout)
+                stdout = []
+            if self.stderr:
+                read_set.append(self.stderr)
+                stderr = []
+
+            while read_set or write_set:
+                rlist, wlist, xlist = select.select(read_set, write_set, [])
+
+                if self.stdin in wlist:
+                    # When select has indicated that the file is writable,
+                    # we can write up to PIPE_BUF bytes without risk
+                    # blocking.  POSIX defines PIPE_BUF >= 512
+                    bytes_written = os.write(self.stdin.fileno(), input[:512])
+                    input = input[bytes_written:]
+                    if not input:
+                        self.stdin.close()
+                        write_set.remove(self.stdin)
+
+                if self.stdout in rlist:
+                    data = os.read(self.stdout.fileno(), 1024)
+                    if data == "":
+                        self.stdout.close()
+                        read_set.remove(self.stdout)
+                    stdout.append(data)
+
+                if self.stderr in rlist:
+                    data = os.read(self.stderr.fileno(), 1024)
+                    if data == "":
+                        self.stderr.close()
+                        read_set.remove(self.stderr)
+                    stderr.append(data)
+
+            # All data exchanged.  Translate lists into strings.
+            if stdout is not None:
+                stdout = ''.join(stdout)
+            if stderr is not None:
+                stderr = ''.join(stderr)
+
+            # Translate newlines, if requested.  We cannot let the file
+            # object do the translation: It is based on stdio, which is
+            # impossible to combine with select (unless forcing no
+            # buffering).
+            if self.universal_newlines and hasattr(file, 'newlines'):
+                if stdout:
+                    stdout = self._translate_newlines(stdout)
+                if stderr:
+                    stderr = self._translate_newlines(stderr)
+
+            self.wait()
+            return (stdout, stderr)
+
+
+def _demo_posix():
+    #
+    # Example 1: Simple redirection: Get process list
+    #
+    plist = Popen(["ps"], stdout=PIPE).communicate()[0]
+    print "Process list:"
+    print plist
+
+    #
+    # Example 2: Change uid before executing child
+    #
+    if os.getuid() == 0:
+        p = Popen(["id"], preexec_fn=lambda: os.setuid(100))
+        p.wait()
+
+    #
+    # Example 3: Connecting several subprocesses
+    #
+    print "Looking for 'hda'..."
+    p1 = Popen(["dmesg"], stdout=PIPE)
+    p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
+    print repr(p2.communicate()[0])
+
+    #
+    # Example 4: Catch execution error
+    #
+    print
+    print "Trying a weird file..."
+    try:
+        print Popen(["/this/path/does/not/exist"]).communicate()
+    except OSError, e:
+        if e.errno == errno.ENOENT:
+            print "The file didn't exist.  I thought so..."
+            print "Child traceback:"
+            print e.child_traceback
+        else:
+            print "Error", e.errno
+    else:
+        print >>sys.stderr, "Gosh.  No error."
+
+
+def _demo_windows():
+    #
+    # Example 1: Connecting several subprocesses
+    #
+    print "Looking for 'PROMPT' in set output..."
+    p1 = Popen("set", stdout=PIPE, shell=True)
+    p2 = Popen('find "PROMPT"', stdin=p1.stdout, stdout=PIPE)
+    print repr(p2.communicate()[0])
+
+    #
+    # Example 2: Simple execution of program
+    #
+    print "Executing calc..."
+    p = Popen("calc")
+    p.wait()
+
+
+if __name__ == "__main__":
+    if mswindows:
+        _demo_windows()
+    else:
+        _demo_posix()