This document aims to give an overview of Windows-specific behaviour you should know about when using Python on Microsoft Windows.
Unlike most Unix systems and services, Windows does not require Python natively and thus does not pre-install a version of Python. However, the CPython team has compiled Windows installers (MSI packages) with every release for many years.
With ongoing development of Python, some platforms that used to be supported earlier are no longer supported (due to the lack of users or developers). Check PEP 11 for details on all unsupported platforms.
见 Python for Windows for detailed information about platforms with pre-compiled installers.
另请参阅
Besides the standard CPython distribution, there are modified packages including additional functionality. The following is a list of popular versions and their key features:
Notice that these packages are likely to install older versions of Python.
In order to run Python flawlessly, you might have to change certain environment settings in Windows.
Windows has a built-in dialog for changing environment variables (following guide applies to XP classical view): Right-click the icon for your machine (usually located on your Desktop and called “My Computer”) and choose there. Then, open the 高级 tab and click the 环境变量 button.
In short, your path is:
In this dialog, you can add or modify User and System variables. To change System variables, you need non-restricted access to your machine (i.e. Administrator rights).
Another way of adding variables to your environment is using the set 命令：
set PYTHONPATH=%PYTHONPATH%;C:\My_python_lib
To make this setting permanent, you could add the corresponding command line to your
autoexec.bat
.
msconfig
is a graphical interface to this file.
Viewing environment variables can also be done more straight-forward: The command prompt will expand strings wrapped into percent signs automatically:
echo %PATH%
Consult set /? for details on this behaviour.
另请参阅
Changed in version 3.3.
Besides using the automatically created start menu entry for the Python interpreter, you might want to start Python in the command prompt. As of Python 3.3, the installer has an option to set that up for you.
At the “Customize Python 3.3” screen, an option called “Add python.exe to search path” can be enabled to have the installer place your installation into the
%PATH%
. This allows you to type
python
to run the interpreter. Thus, you can also execute your scripts with command line options, see
命令行
文档编制。
If you don’t enable this option at install time, you can always re-run the installer to choose it.
The alternative is manually modifying the
%PATH%
using the directions in
附录：设置环境变量
. You need to set your
%PATH%
environment variable to include the directory of your Python distribution, delimited by a semicolon from other entries. An example variable could look like this (assuming the first two entries are Windows’ default):
C:\WINDOWS\system32;C:\WINDOWS;C:\Python33
Python usually stores its library (and thereby your site-packages folder) in the installation directory. So, if you had installed Python to
C:\Python\
, the default library would reside in
C:\Python\Lib\
and third-party modules should be stored in
C:\Python\Lib\site-packages\
.
This is how
sys.path
is populated on Windows:
PYTHONPATH
exists, as described in
环境变量
, its entries are added next. Note that on Windows,
paths in this variable must be separated by semicolons, to distinguish them
from the colon used in drive identifiers (
C:\
等)。
\SOFTWARE\Python\PythonCore\version\PythonPath
under both the
HKEY_CURRENT_USER
and
HKEY_LOCAL_MACHINE
hives. Subkeys which have
semicolon-delimited path strings as their default value will cause each path
to be added to
sys.path
. (Note that all known installers only use
HKLM, so HKCU is typically empty.)
PYTHONHOME
is set, it is assumed as
“Python Home”. Otherwise, the path of the main Python executable is used to
locate a “landmark file” (
Lib\os.py
) to deduce the “Python Home”. If a
Python home is found, the relevant sub-directories added to
sys.path
(
Lib
,
plat-win
, etc) are based on that folder. Otherwise, the core
Python path is constructed from the PythonPath stored in the registry.
PYTHONPATH
is specified in
the environment, and no registry entries can be found, a default path with
relative entries is used (e.g.
.\Lib;.\plat-win
, etc).
The end result of all this is:
python.exe
, or any other .exe in the main Python
directory (either an installed version, or directly from the PCbuild
directory), the core path is deduced, and the core paths in the registry are
ignored. Other “application paths” in the registry are always read.
As of Python 3.3, Python includes a launcher which facilitates running Python scripts. See 用于 Windows 的 Python 启动器 了解更多信息。
Without the Python launcher installed, Python scripts (files with the extension
.py
) will be executed by
python.exe
by default. This executable opens a terminal, which stays open even if the program uses a GUI. If you do not want this to happen, use the extension
.pyw
which will cause the script to be executed by
pythonw.exe
by default (both executables are located in the top-level of your Python installation directory). This suppresses the terminal window on startup.
You can also make all
.py
scripts execute with
pythonw.exe
, setting this through the usual facilities, for example (might require administrative rights):
Launch a command prompt.
Associate the correct file group with
.py
scripts:
assoc .py=Python.File
Redirect all Python files to the new executable:
ftype Python.File=C:\Path\to\pythonw.exe "%1" %*
3.3 版新增。
The Python launcher for Windows is a utility which aids in the location and execution of different Python versions. It allows scripts (or the command-line) to indicate a preference for a specific Python version, and will locate and execute that version.
You should ensure the launcher is on your PATH - depending on how it was installed it may already be there, but check just in case it is not.
From a command-prompt, execute the following command:
py
You should find that the latest version of Python 2.x you have installed is started - it can be exited as normal, and any additional command-line arguments specified will be sent directly to Python.
If you have multiple versions of Python 2.x installed (e.g., 2.6 and 2.7) you will have noticed that Python 2.7 was started - to launch Python 2.6, try the command:
py -2.6
If you have a Python 3.x installed, try the command:
py -3
You should find the latest version of Python 3.x starts.
Let’s create a test Python script - create a file called
hello.py
with the following contents
#! python
import sys
sys.stdout.write("hello from Python %s\n" % (sys.version,))
From the directory in which hello.py lives, execute the command:
py hello.py
You should notice the version number of your latest Python 2.x installation is printed. Now try changing the first line to be:
#! python3
Re-executing the command should now print the latest Python 3.x information. As with the above command-line examples, you can specify a more explicit version qualifier. Assuming you have Python 2.6 installed, try changing the first line to
#! python2.6
and you should find the 2.6 version information printed.
The launcher should have been associated with Python files (i.e.
.py
,
.pyw
,
.pyc
,
.pyo
files) when it was installed. This means that when you double-click on one of these files from Windows explorer the launcher will be used, and therefore you can use the same facilities described above to have the script specify the version which should be used.
The key benefit of this is that a single launcher can support multiple Python versions at the same time depending on the contents of the first line.
若脚本文件首行开始采用
#!
, it is known as a “shebang” line. Linux and other Unix like operating systems have native support for such lines and are commonly used on such systems to indicate how a script should be executed. This launcher allows the same facilities to be using with Python scripts on Windows and the examples above demonstrate their use.
To allow shebang lines in Python scripts to be portable between Unix and Windows, this launcher supports a number of ‘virtual’ commands to specify which interpreter to use. The supported virtual commands are:
/usr/bin/env python
/usr/bin/python
/usr/local/bin/python
python
例如，若脚本首行开始采用
#! /usr/bin/python
The default Python will be located and used. As many Python scripts written to work on Unix will already have this line, you should find these scripts can be used by the launcher without modification. If you are writing a new script on Windows which you hope will be useful on Unix, you should use one of the shebang lines starting with
/usr
.
The shebang lines can also specify additional options to be passed to the Python interpreter. For example, if you have a shebang line:
#! /usr/bin/python -v
Then Python will be started with the
-v
option
Two .ini files will be searched by the launcher -
py.iniin the current user’s “application data” directory (i.e. the directory returned by calling the Windows function SHGetFolderPath with CSIDL_LOCAL_APPDATA) andpy.iniin the same directory as the launcher. The same .ini files are used for both the ‘console’ version of the launcher (i.e. py.exe) and for the ‘windows’ version (i.e. pyw.exe)Customization specified in the “application directory” will have precedence over the one next to the executable, so a user, who may not have write access to the .ini file next to the launcher, can override commands in that global .ini file)
3.4.4.2. Customizing default Python versions ¶
In some cases, a version qualifier can be included in a command to dictate which version of Python will be used by the command. A version qualifier starts with a major version number and can optionally be followed by a period (‘.’) and a minor version specifier. If the minor qualifier is specified, it may optionally be followed by “-32” to indicate the 32-bit implementation of that version be used.
For example, a shebang line of
#!pythonhas no version qualifier, while#!python3has a version qualifier which specifies only a major version.If no version qualifiers are found in a command, the environment variable
PY_PYTHONcan be set to specify the default version qualifier - the default value is “2”. Note this value could specify just a major version (e.g. “2”) or a major.minor qualifier (e.g. “2.6”), or even major.minor-32.If no minor version qualifiers are found, the environment variable
PY_PYTHON{major}(在哪里{major}is the current major version qualifier as determined above) can be set to specify the full version. If no such option is found, the launcher will enumerate the installed Python versions and use the latest minor release found for the major version, which is likely, although not guaranteed, to be the most recently installed version in that family.On 64-bit Windows with both 32-bit and 64-bit implementations of the same (major.minor) Python version installed, the 64-bit version will always be preferred. This will be true for both 32-bit and 64-bit implementations of the launcher - a 32-bit launcher will prefer to execute a 64-bit Python installation of the specified version if available. This is so the behavior of the launcher can be predicted knowing only what versions are installed on the PC and without regard to the order in which they were installed (i.e., without knowing whether a 32 or 64-bit version of Python and corresponding launcher was installed last). As noted above, an optional “-32” suffix can be used on a version specifier to change this behaviour.
范例：
- If no relevant options are set, the commands
pythonandpython2will use the latest Python 2.x version installed and the commandpython3will use the latest Python 3.x installed.- 命令
python3.1andpython2.7will not consult any options at all as the versions are fully specified.- 若
PY_PYTHON=3，命令pythonandpython3will both use the latest installed Python 3 version.- 若
PY_PYTHON=3.1-32, the commandpythonwill use the 32-bit implementation of 3.1 whereas the commandpython3will use the latest installed Python (PY_PYTHON was not considered at all as a major version was specified.)- 若
PY_PYTHON=3andPY_PYTHON3=3.1，命令pythonandpython3will both use specifically 3.1In addition to environment variables, the same settings can be configured in the .INI file used by the launcher. The section in the INI file is called
[defaults]and the key name will be the same as the environment variables without the leadingPY_prefix (and note that the key names in the INI file are case insensitive.) The contents of an environment variable will override things specified in the INI file.例如：
- 设置
PY_PYTHON=3.1is equivalent to the INI file containing:[defaults] python=3.1
- 设置
PY_PYTHON=3andPY_PYTHON3=3.1is equivalent to the INI file containing:[defaults] python=3 python3=3.13.4.5. Diagnostics ¶
若环境变量
PYLAUNCH_DEBUGis set (to any value), the launcher will print diagnostic information to stderr (i.e. to the console). While this information manages to be simultaneously verbose and terse, it should allow you to see what versions of Python were located, why a particular version was chosen and the exact command-line used to execute the target Python.3.5. Additional modules ¶
Even though Python aims to be portable among all platforms, there are features that are unique to Windows. A couple of modules, both in the standard library and external, and snippets exist to use these features.
The Windows-specific standard modules are documented in MS Windows 特定服务 .
3.5.1. PyWin32 ¶
The PyWin32 module by Mark Hammond is a collection of modules for advanced Windows-specific support. This includes utilities for:
- COM (组件对象模型) (COM)
- Win32 API 调用
- 注册
- Event log
- MFC (微软基础类) (MFC) user interfaces
PythonWin is a sample MFC application shipped with PyWin32. It is an embeddable IDE with a built-in debugger.
另请参阅
- Win32 How Do I...?
- by Tim Golden
- Python 和 COM
- by David and Paul Boddie
3.5.2. cx_Freeze ¶
cx_Freeze 是
distutils扩展 (见 扩展 distutils ) which wraps Python scripts into executable Windows programs (*.exefiles). When you have done this, you can distribute your application without requiring your users to install Python.3.5.3. WConio ¶
Since Python’s advanced terminal handling layer,
curses, is restricted to Unix-like systems, there is a library exclusive to Windows as well: Windows Console I/O for Python.WConio is a wrapper for Turbo-C’s
CONIO.H, used to create text user interfaces.3.6. Compiling Python on Windows ¶
若想自己编译 CPython，首先应该做的事情是获取 source 。可以下载最新发行的源代码，或仅仅直接抓取新鲜 checkout .
The source tree contains a build solution and project files for Microsoft Visual C++, which is the compiler used to build the official Python releases. View the
readme.txtin their respective directories:
目录 MSVC 版本 Visual Studio 版本 PC/VS9.0/9.0 2008 PCbuild/10.0 2010 Note that any build directories within the
PCdirectory are not necessarily fully supported. ThePCbuilddirectory contains the files for the compiler used to build the official release.校验
PCbuild/readme.txt了解构建过程的一般信息。对于扩展模块，请翻阅 在 Windows 构建 C/C++ 扩展 .
另请参阅
- Python + Windows + distutils + SWIG + gcc MinGW
- or “Creating Python extensions in C/C++ with SWIG and compiling them with MinGW gcc under Windows” or “Installing Python extension with distutils and without Microsoft Visual C++” by Sébastien Sauvage, 2003
- MingW – Python 扩展
- by Trent Apted et al, 2007
3.7. Other resources ¶
另请参阅
- Python Programming On Win32
- “Help for Windows Programmers” by Mark Hammond and Andy Robinson, O’Reilly Media, 2000, ISBN 1-56592-621-8
- A Python for Windows Tutorial
- by Amanda Birmingham, 2004
- PEP 397 - Python launcher for Windows
- The proposal for the launcher to be included in the Python distribution.