MacOS multi-version Python switching scheme

1. Install homebrew

Official website http://brew.sh/index_zh-cn.html

Open the terminal and paste the following script in the terminal

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Test if the installation is successful

type in the terminal

brew -v

A similar prompt appears, which means the installation is successful

Homebrew 0.9.5 (git revision 1021; last commit 2016-03-30)

2. Install pyenv

type in the terminal

brew install pyenv

Verify that the installation was successful

pyenv -v

Similar results appear, which means the installation is successful

pyenv 20150310

3. View Installable Python Versions

type in the terminal

pyenv install --list

Will list installable Python version numbers

4. Install a specific version of Python

type in the terminal

pyenv install <version>

Install the corresponding Python version, such as:

pyenv install 2.7.11

5. Exception Handling

If the following exception occurs:

Installing Python-2.7.11...
ERROR: The Python zlib extension was not compiled. Missing the zlib?

Please consult to the Wiki page to fix the problem.
https://github.com/yyuu/pyenv/wiki/Common-build-problems


BUILD FAILED (OS X 10.11.5 using python-build 20160130)

Inspect or clean up the working tree at /var/folders/fb/7406jr3s60z_tdpxxqm2s9hh0000gn/T/python-build.20160616162746.48644
Results logged to /var/folders/fb/7406jr3s60z_tdpxxqm2s9hh0000gn/T/python-build.20160616162746.48644.log

Last 10 log lines:
rm -f /Users/Matrix/.pyenv/versions/2.7.11/share/man/man1/python.1
(cd /Users/Matrix/.pyenv/versions/2.7.11/share/man/man1; ln -s python2.1 python.1)
if test "xno" != "xno"  ; then \
        case no in \
            upgrade) ensurepip="--upgrade" ;; \
            install|*) ensurepip="" ;; \
        esac; \
         ./python.exe -E -m ensurepip \
            $ensurepip --root=/ ; \
    fi
yujingyao:2.7.11 Matrix$ CFLAGS="-I$(brew --prefix openssl)/include" LDFLAGS="-L$(brew --prefix openssl)/lib" pyenv install 3.6-Dev
Cloning https://hg.python.org/cpython...
error: please install `mercurial` and try again

Then enter it in the terminal, pay attention to replace the version number of the following code

CFLAGS="-I$(brew --prefix openssl)/include -I$(xcrun --show-sdk-path)/usr/include" \
LDFLAGS="-L$(brew --prefix openssl)/lib" \
pyenv install -v 2.7.11

Valid in EI Capitan

Source: https://github.com/yyuu/pyenv/issues/448

For other exceptions, please refer to https://github.com/yyuu/pyenv/wiki/Common-build-problems

6. View the installed Python version of pyenv

pyenv versions

7. Edit the .bash_profile file

Enter the following command in the terminal to enter the home directory of the current user

cd ~

Enter the following command to open the .bash_profile file

open .bash_profile

If it does not exist, enter the following command to create the file

touch .bash_profile

edit file

open -e .bash_profile

.bash_profileAdd to the pop-up file

if which pyenv > /dev/null; then eval "$(pyenv init -)"; fi

command + ssave document

Enter the following command in the terminal and use the updated .bash_profile content

source .bash_profile

8. Specify the directory to switch the specified version of Python

cd to a specific directory in the terminal, modify the path name by yourself

cd /Users/Matrix/Documents/Projects/Python/3.5.1
Enter:

pyenv local <version>

9. Set the global Python version

type in the terminal

pyenv global <version>

This operation is not recommended, as some system programs may not work properly

10. Check if the switch is successful

cd to a specific directory in the terminal, modify the path name by yourself

cd /Users/Matrix/Documents/Projects/Python/3.5.1

Enter in the terminal: python
The python version used in the current directory will be listed. The same as the set version means the switch is successful.