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This allows you to type python to run the interpreter, and pip for the package installer. Thus, you can also execute your scripts with command line options, see Command line documentation. You need to set your PATH environment variable to include the directory of your Python installation, delimited by a semicolon from other entries.

An example variable could look like this assuming the first two entries already existed :. Python uses it for the default encoding of text files e. If you have any Python 3. The filesystem encoding see PEP for details. The Python launcher for Windows is a utility which aids in locating and executing 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.

It will prefer per-user installations over system-wide ones, and orders by language version rather than using the most recently installed version.

The launcher was originally specified in PEP System-wide installations of Python 3. The launcher is compatible with all available versions of Python, so it does not matter which version is installed. To check that the launcher is available, execute the following command in Command Prompt:. You should find that the latest version of Python 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 installed e. Per-user installations of Python do not add the launcher to PATH unless the option was selected on installation. To run the global interpreter, either deactivate the virtual environment, or explicitly specify the global Python version.

You should notice the version number of your latest Python 2. Now try changing the first line to be:. Re-executing the command should now print the latest Python 3. As with the above command-line examples, you can specify a more explicit version qualifier.

Assuming you have Python 3. This is for backward compatibility and for compatibility with Unix, where the command python typically refers to Python 2. The launcher should have been associated with Python files i. 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.

If the first line of a script file starts with! Linux and other Unix like operating systems have native support for such lines and they are commonly used on such systems to indicate how a script should be executed.

This launcher allows the same facilities to be used with Python scripts on Windows and the examples above demonstrate their use. The supported virtual commands are:. 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. Any of the above virtual commands can be suffixed with an explicit version either just the major version, or the major and minor version.

New in version 3. Furthermore it is possible to specify a major and architecture without minor i. The shebang lines can also specify additional options to be passed to the Python interpreter. For example, if you have a shebang line:.

Then Python will be started with the -v option. The same. In some cases, a version qualifier can be included in a command to dictate which version of Python will be used by the command. For example, a shebang line of! 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 bit Windows with both bit and bit implementations of the same major. This will be true for both bit and bit implementations of the launcher - a bit launcher will prefer to execute a 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. If no relevant options are set, the commands python and python2 will use the latest Python 2.

The command python3. In addition to environment variables, the same settings can be configured in the. INI file used by the launcher.

The contents of an environment variable will override things specified in the INI file. 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. Python usually stores its library and thereby your site-packages folder in the installation directory.

To completely override sys. The file based on the DLL name overrides the one based on the executable, which allows paths to be restricted for any program loading the runtime if desired. When the file exists, all registry and environment variables are ignored, isolated mode is enabled, and site is not imported unless one line in the file specifies import site.

Blank paths and lines starting with are ignored. Each path may be absolute or relative to the location of the file. Import statements other than to site are not permitted, and arbitrary code cannot be specified. Note that. When no. Subkeys which have semicolon-delimited path strings as their default value will cause each path to be added to sys. If a Python home is found, the relevant sub-directories added to sys.

Otherwise, the core Python path is constructed from the PythonPath stored in the registry. If a pyvenv. When running python. When Python is hosted in another. For those who want to bundle Python into their application or distribution, the following advice will prevent conflicts with other installations:. Include a. This will ignore paths listed in the registry and environment variables, and also ignore site unless import site is listed.

If you are loading python3. If you cannot use the previous suggestions for example, you are a distribution that allows people to run python. These will ensure that the files in a system-wide installation will not take precedence over the copy of the standard library bundled with your application. Otherwise, your users may experience problems using your application. Note that the first suggestion is the best, as the others may still be susceptible to non-standard paths in the registry and user site-packages.

Adds pythonXX. Modules specified in the registry under Modules not PythonPath may be imported by importlib.

This finder is enabled on Windows in 3. 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. This includes utilities for:. It is an embeddable IDE with a built-in debugger. When you have done this, you can distribute your application without requiring your users to install Python. If you want to compile CPython yourself, first thing you should do is get the source.

The source tree contains a build solution and project files for Microsoft Visual Studio, which is the compiler used to build the official Python releases. These files are in the PCbuild directory. 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. Windows CE is no longer supported since Python 3 if it ever was.

The Cygwin installer offers to install the Python interpreter as well. See Python for Windows for detailed information about platforms with pre-compiled installers. Navigation index modules next previous Python ». In this case: You may be required to provide administrative credentials or approval Python will be installed into the Program Files directory The Python Launcher for Windows will be installed into the Windows directory Optional features may be selected during installation The standard library can be pre-compiled to bytecode If selected, the install directory will be added to the system PATH Shortcuts are available for all users 4.

After changing the above option, no further configuration is required. Warning Python will always be available for free on the Microsoft Store. Note The embedded distribution does not include the Microsoft C Runtime and it is the responsibility of the application installer to provide this. Deprecated since version 3.

See also Win32 How Do I…? Table of Contents 4. Using Python on Windows 4. The full installer 4. Installation steps 4. Installing Without UI 4. Installing Without Downloading 4.

Modifying an install 4. The Microsoft Store package 4. Known Issues 4. The embeddable package 4. Python Application 4. Embedding Python 4. Alternative bundles 4. Configuring Python 4. Excursus: Setting environment variables 4. Finding the Python executable 4. UTF-8 mode 4. Python Launcher for Windows 4.

Getting started 4. From the command-line 4. Virtual environments 4. From a script 4. From file associations 4. Shebang Lines 4. Arguments in shebang lines 4. Customization 4. Customization via INI files 4. Customizing default Python versions 4. Diagnostics 4. Finding modules 4. Additional modules 4. PyWin32 4. Compiling Python on Windows 4. Other Platforms Previous topic 3. Terms of Service. Business Terms of Service. Our Team.

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