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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallUse pyenv to install and switch between Python versions without replacing your operating system’s Python. Set a user-wide default with pyenv global, a project version with pyenv local, or a temporary version for the current shell with pyenv shell. pyenv routes commands such as python and pip through shims at the front of your PATH.
What pyenv does—and what it does not
pyenv lets you install multiple Python distributions and choose which interpreter your commands use. It supports CPython and PyPy, among other distributions listed by the project. It does not replace the system Python: its special system selection uses the executable found after pyenv’s shims in PATH. The official README describes pyenv as software that “lets you easily switch between multiple versions of Python.”
pyenv manages Python versions, not virtual environments. Once you have selected an interpreter, create an isolated environment with Python’s standard tooling, such as python -m venv .venv, or use the separate pyenv-virtualenv plugin for environment creation and activation integrated with pyenv.
Install pyenv and prepare your system
On Linux and Unix-like systems, the project documents installation with its installer or by cloning the repository. On macOS, it recommends Homebrew for basic usage. Follow the official installation instructions for your operating system and shell.
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Install pyenv using the method for your platform. The documented installer for Linux and Unix-like systems is
curl -fsSL https://pyenv.run | bash; alternatively, clone the repository as described by the project. -
Install the compiler and development libraries needed to build your chosen Python version. Most pyenv-managed releases are compiled from source on your machine, so missing build dependencies commonly cause installation failures.
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Configure your shell using the initialization instructions for your shell and installation method. Restart the shell, or open a new terminal, so the updated
PATHand pyenv initialization take effect. -
Check that pyenv is available by running
pyenv --version.Do these 3 things before closing this tab:
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Build dependencies vary by operating system and Python release. Use the project’s build-environment guidance rather than assuming that pyenv installation alone provides everything a source build needs. The project also documents proxy environment variables and build customization options.
Install a Python version and select it
Run pyenv install -l to see version definitions available to your installation. Choose a listed version, then install it. For example, the following installs Python 3.10.4 and makes it the user-wide default:
pyenv install 3.10.4
pyenv global 3.10.4After changing a selection, check what your shell will run with python --version and pyenv version. You can see the executable path with pyenv which python. If the selected version is not what you expect, check which scope is taking precedence and whether your shell has been initialized as described below.
Choose the right selection scope
| Command | Scope | What it changes |
|---|---|---|
pyenv shell <version> |
Current shell | Sets a temporary override for the current shell session through PYENV_VERSION. |
pyenv local <version> |
Current project directory | Writes the selection to a .python-version file in the current directory. The selection also applies in its subdirectories. |
pyenv global <version> |
User default | Sets the default version when no shell override or applicable project file takes precedence. |
Use pyenv local from the project directory when the project should consistently use a particular interpreter. Because it writes a file into that directory, the choice is visible to tools and collaborators that use pyenv there; decide whether that file belongs in the project’s version control. Use pyenv shell for a short-lived test without changing the project file or global default.
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Why your shell may run the wrong Python
pyenv works by placing its shims directory near the front of PATH. When you type python or pip, the shim asks pyenv which version applies and dispatches the command to that installation. The selection precedence is:
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The
PYENV_VERSIONenvironment variable, commonly set bypyenv shell. -
A
.python-versionfile in the current directory. -
The nearest
.python-versionfile in a parent directory.What’s actually slowing this PC down?
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The global version selection.
If these do not explain the result, inspect the command path with command -v python (or which python) and compare it with pyenv which python. If the first path is not under pyenv’s shims directory, the shell may not have initialized pyenv or another PATH entry may be taking priority. If it is a shim, run pyenv version to see the active version and where that selection came from. Also check for a lingering PYENV_VERSION override and project or parent-directory version files.
Fix common installation and selection problems
A Python build fails
Because most managed releases are built from source, an error during pyenv install often points to a missing compiler or development library. Check the platform-specific suggested build environment and the project’s common build problems guide. For network or proxy failures, review the documented proxy environment variables; for nonstandard builds, consult the project’s build customization options.
A command still resolves to the system interpreter
Confirm that pyenv’s shims directory is early in PATH, the shell initialization has run, and the selected version is installed. Then inspect the active selection with pyenv version. A selection of system is intentional: it directs commands to the executable found after the shims.
Remove an installed version
Uninstall a pyenv-managed version with pyenv uninstall <version>, for example pyenv uninstall 3.10.4. Do not use that command to remove an operating system’s Python; pyenv-installed versions and the system interpreter are separate.
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