Learn to code for free. Get started. Forum Donate. Dominic Fraser. Virtual environments : isolated independent environments that can have both a specific version of Python and of any project-specific packages installed within them, without affecting any other projects. You can use the pyenv shell command to set this environment variable in your current shell session.
The application-specific. You can modify the current directory's. The first. The global version file. You can modify this file using the pyenv global command. If the global version file is not present, pyenv assumes you want to use the "system" Python. In other words, whatever version would run if pyenv weren't in your PATH.
First we could set our local version using pyenv local 3. Final thoughts Between these three tools, we have the ability to collaborate on any project, no matter the version of Python or of the dependencies required.
Thanks for reading! Do I need to install pip? Dominic Fraser Edinburgh, Scotland. The main purpose of the Shebang line is to indicate how a script should be executed on the system. If you are Linux or Unix user, these operating systems have native support for executing Shebang lines. Same shebang lines, you can use with Python script on windows as well.
This simple one line of code to run different python versions in cmd on the same system helps me a lot for many of the Python projects which has a dependency for running on particular Python version.
I do write Python code every day and share my knowledge. Check out my complete Python tutorial for more of such tricks. Save my name, email, and website in this browser for the next time I comment. What do you want to Learn Today?
This can be done with. This could be done with. In either case, the --prefix option defines the installation base, and the --exec-prefix option defines the platform-specific installation base, which is used for platform-specific files. Currently, this just means non-pure module distributions, but could be expanded to C libraries, binary executables, etc. If --exec-prefix is not supplied, it defaults to --prefix. Files are installed as follows:. There is no requirement that --prefix or --exec-prefix actually point to an alternate Python installation; if the directories listed above do not already exist, they are created at installation time.
Incidentally, the real reason the prefix scheme is important is simply that a standard Unix installation uses the prefix scheme, but with --prefix and --exec-prefix supplied by Python itself as sys. Note that installing extensions to an alternate Python installation has no effect on how those extensions are built: in particular, the Python header files Python.
It is your responsibility to ensure that the interpreter used to run extensions installed in this way is compatible with the interpreter used to build them. The best way to do this is to ensure that the two interpreters are the same version of Python possibly different builds, or possibly copies of the same build.
The installation base is defined by the --prefix option; the --exec-prefix option is not supported under Windows, which means that pure Python modules and extension modules are installed into the same location. You might want to tweak just one or two directories while keeping everything under the same base directory, or you might want to completely redefine the installation scheme. To create a custom installation scheme, you start with one of the alternate schemes and override some of the installation directories used for the various types of files, using these options:.
These override options can be relative, absolute, or explicitly defined in terms of one of the installation base directories. As you might expect, you can override this directory with the --install-scripts option; in this case, it makes most sense to supply a relative path, which will be interpreted relative to the installation base directory your home directory, in this case :.
If you maintain Python on Windows, you might want third-party modules to live in a subdirectory of prefix , rather than right in prefix itself.
This is almost as easy as customizing the script installation directory—you just have to remember that there are two types of modules to worry about, Python and extension modules, which can conveniently be both controlled by one option:. The specified installation directory is relative to prefix. If you want to define an entire installation scheme, you just have to supply all of the installation directory options.
The recommended way to do this is to supply relative paths; for example, if you want to maintain all Python module-related files under python in your home directory, and you want a separate directory for each platform that you use your home directory from, you might define the following installation scheme:. Obviously, specifying the entire installation scheme every time you install a new module distribution would be very tedious.
Thus, you can put these options into your Distutils config file see section Distutils Configuration Files :. Note that these two are not equivalent if you supply a different installation base directory when you run the setup script.
For example,. These are Distutils configuration variables, which bear a strong resemblance to environment variables. See section Distutils Configuration Files for details. When a virtual environment is activated, any options that change the installation path will be ignored from all distutils configuration files to prevent inadvertently installing projects outside of the virtual environment.
When the Python interpreter executes an import statement, it searches for both Python code and extension modules along a search path. A default value for the path is configured into the Python binary when the interpreter is built. You can determine the path by importing the sys module and printing the value of sys.
The null string in sys. There are several different ways to add the directory. Path configuration files have an extension of. Because the new paths are appended to sys. See the documentation of the site module for more information.
A slightly less convenient way is to edit the site. So you could simply edit site. However, if you reinstall the same major version of Python perhaps when upgrading from 2. There are two environment variables that can modify sys. Note that directories must exist in order to be added to sys. The file you should be downloading is called Windows x86—64 executable installer , or Windows x86 executable installer if for some reason you are using a bit windows.
Assuming you are using Code Inspections, you might need to tell PyCharm which python version to inspect for. Currently, your virtualenv contains only the crucial packages, pip and setuptools. To install more packages:. I hope my journey helped you with yours, and may we all enjoy happy coding, with as little as IT-friction as possible :D.
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