Homebrew’s Python is not for you. It exists to serve Homebrew, or more accurately, Homebrew’s other formulae. The primary purpose of Homebrew’s Python formula is to enable other Python-dependent Homebrew packages to work. If installing Homebrew’s Python allows you to run the occasional Python script or access the REPL. This will allow you to install any version of Python you'd like. First update Homebrew package manager. Brew update && brew doctor. Install pyenv version manager. Brew install pyenv Step 2. Apr 11, 2021 Teams. Connect and share knowledge within a single location that is structured and easy to search. Have Homebrew manage Python 3 The Homebrew project provides a free and open source package manager for macOS that many people rely on. It gives Apple users a power similar to apt-get or yum. If you are a Homebrew user, you may already have Python installed.
| require 'formula' |
| <<-COMMENTS |
| This is the Homebrew formula for Python. |
| Versions |
| -------- |
| This formula is currently tracking version 2.6.x. |
| If you are looking for newer versions of Python, check out these forks: |
| 2.7.x: http://github.com/mxcl/homebrew/issues/issue/1773 |
| 3.1.x: http://github.com/mxcl/homebrew/issues/issue/1188 |
| Options |
| ------- |
| There are a few options for customzing the build. |
| --universal: Builds combined 32-/64-bit Intel binaries. |
| --framework: Builds a 'Framework' version of Python. |
| --static: Builds static instead of shared libraries. |
| site-packages |
| ------------- |
| The 'site-packages' folder lives in the Cellar, under the 'lib' folder |
| for normal builds, and under the 'Frameworks' folder for Framework builds. |
| A .pth file is added to the Cellar site-packages that adds the corresponding |
| HOMEBREW_PREFIX folder (/usr/local/lib/python2.6/site-packages by default) |
| to sys.path. Note that this alternate folder doesn't itself support .pth files. |
| pip / distribute |
| ---------------- |
| The pip (and distribute) formulae in Homebrew are designed only to work |
| against a Homebrew-installed Python, though they provide links for |
| manually installing against a custom Python. |
| pip and distribute are installed directly into the Cellar site-packages, |
| since they need to install to a place that supports .pth files. |
| The pip & distribute formuale use the 'site_packages' method defined here |
| to get the appropriate site-packages path. |
| COMMENTS |
| # Was a Framework build requested? |
| def build_framework?; ARGV.include? '--framework'; end |
| # Are we installed or installing as a Framework? |
| def as_framework? |
| (self.installed? and File.exists? prefix+'Frameworks/Python.framework') or build_framework? |
| end |
| class Python26 <Formula |
| url 'http://www.python.org/ftp/python/2.6.6/Python-2.6.6.tar.bz2' |
| homepage 'http://www.python.org/' |
| md5 'cf4e6881bb84a7ce6089e4a307f71f14' |
| depends_on 'sqlite' => :optional # Prefer over OS X's older version |
| depends_on 'readline' => :optional # Prefer over OS X's libedit |
| depends_on 'gdbm' => :optional |
| def options |
| [ |
| ['--framework', 'Do a 'Framework' build instead of a UNIX-style build.'], |
| ['--universal', 'Build for both 32 & 64 bit Intel.'], |
| ['--static', 'Build static libraries.'] |
| ] |
| end |
| # Skip binaries so modules will load; skip lib because it is mostly Python files |
| skip_clean ['bin', 'lib'] |
| def site_packages |
| # The Cellar location of site-packages |
| if as_framework? |
| # If we're installed or installing as a Framework, then use that location. |
| return prefix+'Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages' |
| else |
| # Otherwise, use just the lib path. |
| return lib+'python2.6/site-packages' |
| end |
| end |
| def prefix_site_packages |
| # The HOMEBREW_PREFIX location of site-packages |
| HOMEBREW_PREFIX+'lib/python2.6/site-packages' |
| end |
| def validate_options |
| if build_framework? and ARGV.include? '--static' |
| onoe 'Cannot specify both framework and static.' |
| exit 99 |
| end |
| end |
| def install |
| validate_options |
| args = ['--prefix=#{prefix}'] |
| if ARGV.include? '--universal' |
| args << '--enable-universalsdk=/' << '--with-universal-archs=intel' |
| end |
| if build_framework? |
| args << '--enable-framework=#{prefix}/Frameworks' |
| else |
| args << '--enable-shared' unless ARGV.include? '--static' |
| end |
| system './configure', *args |
| system 'make' |
| ENV.j1 # Some kinds of installs must be serialized. |
| system 'make install' |
| # Add the Homebrew prefix path to site-packages via a .pth |
| prefix_site_packages.mkpath |
| (site_packages+'homebrew.pth').write prefix_site_packages |
| end |
| def caveats |
| framework_caveats = <<-EOS.undent |
| Framework Python was installed to: |
| #{prefix}/Frameworks/Python.framework |
| You may want to symlink this Framework to a standard OS X location, |
| such as: |
| mkdir ~/Frameworks |
| ln -s '#{prefix}/Frameworks/Python.framework' ~/Frameworks |
| EOS |
| site_caveats = <<-EOS.undent |
| The site-packages folder for this Python is: |
| #{site_packages} |
| We've added a 'homebrew.pth' file to also include: |
| #{prefix_site_packages} |
| EOS |
| general_caveats = <<-EOS.undent |
| You may want to create a 'virtual environment' using this Python as a base |
| so you can manage multiple independent site-packages. See: |
| http://pypi.python.org/pypi/virtualenv |
| If you install Python packages via pip, binaries will be installed under |
| Python's cellar but not automatically linked into the Homebrew prefix. |
| You may want to add Python's bin folder to your PATH as well: |
| #{bin} |
| EOS |
| s = site_caveats+general_caveats |
| s = framework_caveats + s if as_framework? |
| return s |
| end |
| end |
- Warnings
- Installation
- PATH and .bash_profile
- Homebrew - pyenv
- Uninstall python
- Homebrew
It’s easy to install multiple versions of python on a Mac computer using installers from python.org, Homebrew, Conda, or other sources. This could create conflicts if a user wants to run one version of python but bash calls a different version instead.
This is guide will show you how to:
- modify your bash profile to change which version of python is called by bash first.
- use virtual environments to specify a version of python that will run a project.
- uninstall specific versions of python.
Mac OS needs python
DO NOT remove any versions of Python found in the following folders:
/usr/binsystem/Library
These versions of Python—which should be Python 2.7—are installed by Apple and used by Mac OS and other software to perform some functions. Deleting Python from these directories will break Mac OS and force you to reinstall it on your computer.
Other projects may need specific versions of python
You may have a python project or you may use python packages that require particular versions of Python. Uninstalling those versions would prevent those projects or packages from working until that version of python is reinstalled. For example, Python 3 is a dependency of Numpy; if you uninstalled Python 3, then Numpy wouldn’t work until you reinstalled Python 3.
Three common methods of installing python can be found here:
python.org
The python.org (python.org) installer can be found here.
Homebrew
First install Homebrew. The instructions are here, or enter the following command:
To install Python 3:
To install Python 2:
Anaconda
Anaconda is generally used for scientific and machine learning applications.
For Ananconda follow installation instructions here.
Miniconda is a stripped down version of Anaconda.
For Miniconda follow installation instructions here.
PATH
The path is a list of directories that your shell will look through when you execute a command. You can display the path on your computer using the echo $PATH command:
The directories above are separated by a colon, this is what they look like displayed in sequence:
- /Library/Frameworks/Python.framework/Versions/3.7/bin
- /Users/username/anaconda3/bin
- /Library/Frameworks/Python.framework/Versions/2.7/bin
- /Users/username/miniconda2/bin
- /Users/username/miniconda3/bin
- /Library/Frameworks/Python.framework/Versions/3.6/bin
- /usr/local/bin
- /usr/bin
- /bin
- /usr/sbin
- /sbin
- /usr/texbin
- /opt/X11/bin
- /usr/X11/bin
- /usr/local/git/bin
When you ask your shell to run a particular command or run an interpreter, python for example, the shell looks through the different directories listed in the PATH in order they’re presented above. When the shell finds that command, it stops and calls it even if there is another version of the same command, with the same name, further down in the list.
.bash_profile
The bash profile is a set of instructions that are run by the shell when the user logs in to bash. You can add a variety of preferences to the bash profile, including modifications to the PATH. When anaconda, miniconda or other versions of python are installed they automatically add paths to their respective versions of python to the top of the bash profile.
Bash reads the bash profile in sequential order — from top to bottom — and adds those paths to the PATH in the order that they’re read. This means that the last path at the bottom of the bash profile will end up as the first path in the PATH. This means that if you have Python 3.6 installed on your computer, and then decide to add python 3.7, but keep 3.6, the installer will add Python 3.7 to the top of the bash profile but it will end up after python 3.6 in the PATH. Entering python3 in bash will call python 3.6, not 3.7.
If that was confusing compare the order that the python paths are added to my bash profile below to the PATH listed above. You’ll notice that their respective orders are opposite from each other.
Enter the following command to open the bash profile in TextEdit:
My .bash_profile currently looks like this:
If you want to keep all of your installed versions of python, but want bash to open a different version first, just copy and paste it to the bottom of the bash profile. If you don’t want bash to run a particular version of python then delete it from bash profile and uninstall that version by following the instructions further down.
Don’t forget to save the bash profile before closing TextEdit. You also have to reload the bash profile in bash before any changes take effect. Just enter one of the following commands:
source ~/.bash_profile. ~/.bash_profile
Pyenv is a Homebrew package that allows a user to install multiple versions of python in Homebrew and specify which version of python they’d like to run.
Install pyenv: U232 p9 driver windows 8.
Install different versions of python:
Show which versions of python are installed:
The asterisk indicates that the system version of python is active, but 3.5.0 and 3.6.0 are also installed.
Pyenv Local
Create a folder called PythonLocalProject, then display the version of python called by bash by entering python -V:
Now enter:
This creates a .python-version file which tells pyenv which version of python to run in that directory.
Entering ls -la shows us that file:
Now enter pyenv versions:
And running this command shows which version of python is called by pyenv:
To change pyenv to the system version of version 3.6.0 enter:
This procedure is fine, you can set a version of python to run in a particular folder. But what if you want to use pyenv to set a global version of python.
Pyenv Global
Pyenv gives these instructions when you enter pyenv init in bash:
Open the bash profile:
open ~/.bash_profile
Add this text to the bottom of the file:
eval '$(pyenv init -)'
Save the file and then enter:
source ~/.bash_profile
Entering echo $PATH will show that a pyenv shim has been added to the beginnning of the path:
/Users/username/.pyenv/shims:
And which python will return:
/Users/username/.pyenv/shims/python
This means that bash will run the version of python set by pyenv.
Navigate to a folder that doesn’t have a .python-version file and enter:
Brew Python
This shows us that the global version of python is 3.6.0 and it is set by pyenv.
So this shows that bash will run whichever version of python that is set in pyenv.
If you navigate back to the PythonLocalProject folder with the .python-version file and run python -V you will notice that it doesn’t run the global version of python, it runs whichever version was last set with the pyenv local command.
Garageband midi cable.
We can use the which command to identify where specific versions of python are located:
This shows some overlap as some versions of python appear in both searches.
The locations of the anaconda and miniconda versions of python are self explanatory, so are the pyenv installs, the python.org installer places python in the /Library/Frameworks/Python.framework/ directory. Homebrew installs all packages, including python, in /usr/local/Cellar, then Homebrew adds a symlink to /usr/local/binso that its version of python can be found in the path. Finally, Apple installs python in /usr/bin. Remember, don’t delete that version.
Follow these instructions if you want to remove particular versions of python.
python.org
The python.org installer places all it’s installed files in the following folders:
- The system applications folder,
/Applications /Library/Frameworks/Python.framework/usr/local/bin
To delete all versions of python that were installed using the python.org installer, enter these commands in terminal:
To remove particular versions of python, you have to refer to the particular framework. The frameworks are installed in /Library/Frameworks/Python.framework and particular versions are found in /Library/Frameworks/Python.framework/Versions/X.Y. So for example if you wanted to uninstall only version 3.5 but leave other versions you would enter the following commands in bash:
Homebrew
To uninstall python that was installed using homebrew you need to identify what versions of python have been installed by Homebrew:
Enter:
Currently brew refers to python3 as python and python 2 is called python@2.
Homebrew Python 3.7
To uninstall both python2 and python3 enter the following:
Homebrew will refuse to uninstall python if it has dependencies, just uninstall python and ignore the dependencies:
Or, add the dependencies to the list of items to be uninstalled:
Troubleshooting
It’s possible to have Homebrew’s Python directory at the beginning of the $PATH but calling python will still start the Apple installed version of Python or some other version. If that’s the case it’s possible that Homebrew’s Python install has become unlinked. This command will unlink and relink Python in Homebrew:
Uninstall Python from Pyenv
To list versions of python installed using pyenv enter:
To uninstall versions of python installed using pyenv enter:
Anaconda
The official removal instructions are found here, but deleting anaconda and miniconda is easy.
Anaconda and miniconda are installed in the users home directory: ~/miniconda2, ~/miniconda3,~/anaconda2, or ~/anaconda3
Depending on which version or versions you have, just enter the following commands:
Homebrew Python 3 Download
Anaconda and miniconda also use several invisible files. Delete them by entering this command:
Install Python 3 Mac
- Python Removal Instructions - towards the bottom of the README file.
And now for something completely different.