浅墨散人
2018-09-26
目录

在MacOS上安装Python2和Python3

# 简介

由于MacOS自带了Python2，是供MacOS系统自用的Python2，主要用于运行MacOS系统相关的程序，不适合我们学习开发。一般情况下我们不要改动该Python环境里的内容，并且也不能删除。如果想用其他Python版本只能另外安装。

所以本篇文章主要是为了不改动自带Python环境的情况下，在MacOS上安装另外安装Python2和Python3。

警告

MacOS自带的Python是2.7.10

  1. 安装路径在/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7
  2. 可执行文件路径在/usr/bin/python

# 查看MacOS系统自带的Python

输入/usr/bin/python可使用系统自带的Python

输入如下命令，查看默认Python版本

$ python --version  # 查看默认Python版本
Python 2.7.10
$ which python # 查看默认Python可执行文件的路径
/usr/bin/python
$ ls /usr/bin/python # 查看默认Python可执行文件的路径
/usr/bin/python
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# Homebrew

# Homebrew 能干什么?

使用 Homebrew 安装 Apple 没有预装但 你需要的东西 (opens new window)。

# 安装Homebrew

brew官网 (opens new window)

在iTerm2中输入以下命令安装Homebrew

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
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# Homebrew软件安装后的位置

  1. 配置文件在/usr/local/etc中
  2. 安装文件在/usr/local/Cellar中
  3. 二进制可执行程序的软连接在/usr/local/bin中

# 安装Python2

安装前先确定是否已经通过brew安装了python

$ brew uninstall python
Error: No such keg: /usr/local/Cellar/python
$ brew uninstall python3
Error: No such keg: /usr/local/Cellar/python
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# 通过brew安装python2

在终端中输入brew install python@2命令

$ brew install python@2
==> Downloading https://homebrew.bintray.com/bottles/python@2-2.7.15_1.mojave.bottle.8.tar.gz
######################################################################## 100.0%
==> Pouring python@2-2.7.15_1.mojave.bottle.8.tar.gz
==> /usr/local/Cellar/python@2/2.7.15_1/bin/python -s setup.py --no-user-cfg install --force --verbose --single-version-externally-managed --record=instal
==> /usr/local/Cellar/python@2/2.7.15_1/bin/python -s setup.py --no-user-cfg install --force --verbose --single-version-externally-managed --record=instal
==> /usr/local/Cellar/python@2/2.7.15_1/bin/python -s setup.py --no-user-cfg install --force --verbose --single-version-externally-managed --record=instal
==> Caveats
Pip and setuptools have been installed. To update them
  pip install --upgrade pip setuptools

You can install Python packages with
  pip install <package>

They will install into the site-package directory
  /usr/local/lib/python2.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python
==> Summary
🍺  /usr/local/Cellar/python@2/2.7.15_1: 4,701 files, 82.7MB
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可以看到Python2的site-packages是在/usr/local/lib/python2.7/site-packages

# 安装Python3

安装前先确定是否已经通过brew安装了python

$ brew uninstall python
Error: No such keg: /usr/local/Cellar/python
$ brew uninstall python3
Error: No such keg: /usr/local/Cellar/python
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# 通过brew安装python3

安装Python3，在iTerim2中输入如下命令：brew install python OR brew install python3

$ brew install python
==> Installing dependencies for python: xz
==> Installing python dependency: xz
==> Downloading https://homebrew.bintray.com/bottles/xz-5.2.4.mojave.bottle.tar.gz
######################################################################## 100.0%
==> Pouring xz-5.2.4.mojave.bottle.tar.gz
🍺  /usr/local/Cellar/xz/5.2.4: 92 files, 1MB
==> Installing python
==> Downloading https://homebrew.bintray.com/bottles/python-3.7.2.mojave.bottle.tar.gz
######################################################################## 100.0%
==> Pouring python-3.7.2.mojave.bottle.tar.gz
==> /usr/local/Cellar/python/3.7.2/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.2/bin --
==> /usr/local/Cellar/python/3.7.2/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.2/bin --
==> /usr/local/Cellar/python/3.7.2/bin/python3 -s setup.py --no-user-cfg install --force --verbose --install-scripts=/usr/local/Cellar/python/3.7.2/bin --
==> Caveats
Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/python/libexec/bin

If you need Homebrew's Python 2.7 run
  brew install python@2

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /usr/local/lib/python3.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python
==> Summary
🍺  /usr/local/Cellar/python/3.7.2: 3,833 files, 59.3MB
==> Caveats
==> python
Python has been installed as
  /usr/local/bin/python3

Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
`python3`, `python3-config`, `pip3` etc., respectively, have been installed into
  /usr/local/opt/python/libexec/bin

If you need Homebrew's Python 2.7 run
  brew install python@2

You can install Python packages with
  pip3 install <package>
They will install into the site-package directory
  /usr/local/lib/python3.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python
$ 
$
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可以看到Python3的site-packages是在/usr/local/lib/python3.7/site-packages

# 设置PATH

通过上面的安装步骤，可以通过ll /usr/local/Cellar | grep python命令中查看到安装的Python2和Python3

$ ll /usr/local/Cellar | grep python
drwxr-xr-x  3 fangzheng  staff    96B  4 16 18:35 python
drwxr-xr-x  3 fangzheng  staff    96B  4 16 18:27 python@2
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# 设定路径$PATH (不和系统Python干扰)

默认情况下，macOS自带的Python在/usr/bin目录里，里面也有一份Python 然后我们自己安装的Python在/usr/local/Cellar目录里 这样在terminal打上python指令时，谁会被开启呢？ 因为路径有顺序，所以它会先找到系统的Python 现在就要来解决这个问题

sudo vi /etc/paths
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把paths文件修改成如下顺序

/usr/local/bin
/usr/bin
/bin
/usr/sbin
/sbin
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# 最终确认

# 1. 通过版本确认

在终端中输入如下命令：

提示

确认最后输出的版本是刚才安装通过brew安装python2的版本

# 查看Python2的版本
$ python -V
Python 2.7.15
$ python2 -V
Python 2.7.15
# 查看Python3的版本
$ python3 -V
Python 3.7.2
$
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# 2. 通过路径确认

# 通过which查看路径：

提示

确认是否以/usr/local/开头

# 查看Python2的路径
$ which python
/usr/local/bin/python
# 查看Python3的路径
$ which python3
/usr/local/bin/python3
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# 通过ls -l which查看路径:

提示

确认是否包含../Cellar/路径

$ ls -l `which pip`
lrwxr-xr-x  1 fangzheng  admin  35  4 16 18:27 /usr/local/bin/pip -> ../Cellar/python@2/2.7.15_1/bin/pip
$ ls -l `which pip3`
lrwxr-xr-x  1 fangzheng  admin  31  4 16 18:35 /usr/local/bin/pip3 -> ../Cellar/python/3.7.2/bin/pip3
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# 通过pip show pip查看路径：

提示

确认Location: /usr/local/lib/python2.7/site-packages是否以/usr/local/lib/开头

 










 











$ pip show pip  # python2
Name: pip
Version: 18.1
Summary: The PyPA recommended tool for installing Python packages.
Home-page: https://pip.pypa.io/
Author: The pip developers
Author-email: pypa-dev@groups.google.com
License: MIT
Location: /usr/local/lib/python2.7/site-packages
Requires:
Required-by:
$ pip3 show pip  # python3
Name: pip
Version: 18.1
Summary: The PyPA recommended tool for installing Python packages.
Home-page: https://pip.pypa.io/
Author: The pip developers
Author-email: pypa-dev@groups.google.com
License: MIT
Location: /usr/local/lib/python3.7/site-packages
Requires:
Required-by:
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以上命令确认完成都没什么问题后，MacOS的Python2和Python3共存就已经安装好了。

# 在PyCharm中设置虚拟环境

这里使用PyCharm的virtualenv虚拟环境，virtualenv工具与PyCharm捆绑在一起，因此用户无需安装它。

在PyCharm中设置了虚拟环境后，可以保证不影响系统自带的Python环境 按Command + ,设置解释器 设置解释器

点击右边⚙ 即可设置

图例说明

  1. 说明虚拟环境存放的位置

警告

该目录py2.7必须是空目录,如果目录已经存在，需要先删除后建虚拟环境

  1. 选择解释器：py2.7选择python2， py3.7选择python3即可
  2. 使用全局site-packages，这样的话就会使用全局的/usr/local/lib/python2.7/site-packages 或者 /usr/local/lib/python3.7/site-packages下的所有包
  3. 表示将本虚拟环境供本工作空间(pydemo)所有项目使用

以下是新建py2.7解释器截图 Python2.7虚拟环境配置 以下是新建py3.7解释器截图 Python3.7虚拟环境设置

然后在你的项目中选择相应的解释器即可。。

例如： 选项py2.7作为本项目的解释器

# 参考链接

  1. Mac 上如何正确的安装Python2.7和Python3 (opens new window)

  2. 在Mac OS X上安装Python 2¶ (opens new window)

  3. Configure a virtual environment (opens new window)

# Mac 卸载干净python3.7

Mac 卸载干净python3.7 (opens new window)

#Python
最后更新时间: 2022/7/23 10:17:11
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