Interested in programming since he was 14 years old, Carlos is a self-taught programmer and founder and author of most of the articles at Our Code World. Light Dark. Carlos Delgado March 16, Share this article. If I recall correctly, I've had Python 2. The answer would also be a useful solution, no matter which OS your on. Sign up or log in Sign up using Google. Sign up using Facebook.
Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. Besides the standard CPython distribution, there are modified packages including additional functionality. The following is a list of popular versions and their key features:. Popular scientific modules such as numpy, scipy and pandas and the conda package manager.
Note that these packages may not include the latest versions of Python or other libraries, and are not maintained or supported by the core Python team. To run Python conveniently from a command prompt, you might consider changing some default environment variables in Windows. If you regularly use multiple versions of Python, consider using the Python Launcher for Windows.
Windows allows environment variables to be configured permanently at both the User level and the System level, or temporarily in a command prompt. To temporarily set environment variables, open Command Prompt and use the set command:.
These changes will apply to any further commands executed in that console, and will be inherited by any applications started from the console. Including the variable name within percent signs will expand to the existing value, allowing you to add your new value at either the start or the end. Modifying PATH by adding the directory containing python. 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.
Administrator rights. Windows will concatenate User variables after System variables, which may cause unexpected results when modifying PATH.
Besides using the automatically created start menu entry for the Python interpreter, you might want to start Python in the command prompt. The installer has an option to set that up for you. 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 2. 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 commands 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. Part of the problem here is that is the OP is asking for the "home dir" of a user, but there is no such thing under Windows.
Or, rather, there are several such things. Which is certainly one of the definitions of "home dir". The page you refer to and other similar suggestions of using the os.
Left as an exercise Haven't yet heard back from the OP as to whether that's given him what he wants or not.
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