How to use the command 'pyenv' (with examples)

Pyenv is a command line tool that allows users to easily switch between multiple versions of Python. It provides a simple and convenient way to manage different Python versions on the same machine.

Use case 1: List all available commands

Code:

pyenv commands

Motivation: This use case is helpful when you want to quickly get a list of all available commands provided by pyenv. It allows you to better understand the functionality and features provided by the tool.

Explanation: The commands subcommand is used to list all available commands provided by pyenv.

Example output:

available
commands
exec
global
help
hooks
init
install
local
prefix
rehash
root
shell
uninstall
update
version
version-file
versions
whence

Use case 2: List all Python versions under the ${PYENV_ROOT}/versions directory

Code:

pyenv versions

Motivation: This use case is useful when you want to see a list of all Python versions installed on your machine using pyenv. It helps you keep track of the different Python versions available for use.

Explanation: The versions subcommand is used to list all Python versions under the ${PYENV_ROOT}/versions directory, which is the default directory where pyenv installs different Python versions.

Example output:

  3.8.12
  3.9.7
* 3.10.0 (set by /Users/user/.pyenv/version)

Use case 3: List all Python versions that can be installed from upstream

Code:

pyenv install --list

Motivation: This use case allows you to get a list of all Python versions that can be installed from upstream sources. It helps you know the available versions to install using pyenv.

Explanation: The install --list subcommand is used to list all Python versions that are available to be installed from upstream sources. This includes versions maintained by the Python Software Foundation and community contributors.

Example output:

  ...
  2.7.10
  3.9.7
  ...

Use case 4: Install a Python version under the ${PYENV_ROOT}/versions directory

Code:

pyenv install 2.7.10

Motivation: This use case is useful when you want to install a specific version of Python under the ${PYENV_ROOT}/versions directory. It enables you to easily switch between different Python versions using pyenv.

Explanation: The install subcommand followed by the desired Python version installs the specified version of Python under the ${PYENV_ROOT}/versions directory.

Example output:

python-build: definition not found: 2.7.10

The following versions contain `2.7.10' in the name/description:
  ...

You can list all available versions using `pyenv install --list'.

If the version you need is missing, try upgrading pyenv:

  brew update
  brew upgrade pyenv

Use case 5: Uninstall a Python version under the ${PYENV_ROOT}/versions directory

Code:

pyenv uninstall 2.7.10

Motivation: This use case is helpful when you want to uninstall a specific version of Python installed under the ${PYENV_ROOT}/versions directory. It allows you to clean up unnecessary Python versions and manage disk space effectively.

Explanation: The uninstall subcommand followed by the desired Python version uninstalls the specified version of Python from the ${PYENV_ROOT}/versions directory.

Example output:

python-build: use openssl from homebrew
Uninstalling Python-2.7.10...
python-build: successfully removed /Users/user/.pyenv/versions/2.7.10

Use case 6: Set Python version to be used globally in the current machine

Code:

pyenv global 2.7.10

Motivation: This use case is helpful when you want to set a specific Python version globally on your machine. It allows you to specify a default Python version that will be used in all contexts.

Explanation: The global subcommand followed by the desired Python version sets the specified version as the global Python version to be used on the current machine.

Example output: No output is shown after running this command.

Use case 7: Set Python version to be used in the current directory and all directories below it

Code:

pyenv local 2.7.10

Motivation: This use case is useful when you want to set a specific Python version for a particular directory and its subdirectories, overriding the globally set Python version. It allows you to have different Python versions for different projects.

Explanation: The local subcommand followed by the desired Python version sets the specified version as the local Python version to be used in the current directory and all directories below it.

Example output: No output is shown after running this command.

Conclusion

The pyenv command provides an easy and convenient way to manage multiple versions of Python on a single machine. Whether you need to list available commands, manage installed versions, or set global/local versions, pyenv has you covered. With the use cases and examples provided, you should now be equipped to start using pyenv effectively in your Python development workflow.