pip install出现 Permission denied 权限问题，在网上找到以下几种方法：
- brew install Python
Chaim:electrum Chaim$ brew install Python
Warning: python 2.7.14_3 is already installed, it's just not linked.
You can use `brew link python` to link this version.
Chaim:electrum Chaim$ brew link python
Linking /usr/local/Cellar/python/2.7.14_3... 26 symlinks created
版本不对，那安装Python3
Chaim:electrum Chaim$ brew install Python3
Updating Homebrew...
Warning: python3 3.6.4_2 is already installed, it's just not linked.
You can use `brew link python3` to link this version.
Chaim:electrum Chaim$ brew link python3
Linking /usr/local/Cellar/python3/3.6.4_2...
Error: Could not symlink bin/2to3-3.6
Target /usr/local/bin/2to3-3.6
already exists. You may want to remove it:
rm '/usr/local/bin/2to3-3.6'
To force the link and overwrite all conflicting files:
brew link --overwrite python3
To list all files that would be deleted:
brew link --overwrite --dry-run python3
Chaim:electrum Chaim$ brew link --overwrite python3
Linking /usr/local/Cellar/python3/3.6.4_2... 19 symlinks created
还是出同样错误，可能我哪个地方没弄清楚...
- pip install xxx –user
Chaim:electrum Chaim$ pip3 install pyqt5-macos-built --user
Collecting pyqt5-macos-built
Using cached pyqt5-macos-built-5.5.0.tar.gz
Requirement already satisfied: docopt in /Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages (from pyqt5-macos-built)
Installing collected packages: pyqt5-macos-built
Running setup.py install for pyqt5-macos-built ... done
Successfully installed pyqt5-macos-built-5.5.0
Chaim:electrum Chaim$ pyrcc5
/usr/local/bin/python3.6: No module named PyQt5.pyrcc_main
Mac中自带python的package目录在/Library/Python/2.7/site-packages/，如果直接用pip install则默认是在此目录中，也即系统目录。
而–user的安装目录在/Users/Ussopo/Library/Python/2.7/lib/python/site-packages/，不触及SIP，因此install success。
网上说这种方法安装是成功，但调用可能会有问题，结果的确还是出同样错误，可能还是有哪个地方没弄清楚...
- 关闭SIP
1、重启电脑，按住Command+R(直到出现苹果标志)进入Recovery Mode(恢复模式)，左上角菜单里找到实用工具终端；
2、输入csrutil disable回车重启Mac即可，如果想重新启动SIP机制重复上述步骤改用csrutil enable即可。
这个方法以前好像试过，不想试了，还是保留系统的安全模式吧，只能用大家都推荐的pyenv了...
- anaconda
这个网上有反应说千万别在mac上装，弄得乱七八糟，好吧...
- pyenv
大家都说好的方法，希望能解决问题！
传送门 https://www.cnblogs.com/anpengapple/p/5907416.html
下载virtualenv，拷贝成2、3两个版本，并建立链接，如下：
Chaim:Downloads Chaim$ sudo cp -r virtualenv-15.1.0 /usr/local/virtualenv2
Chaim:Downloads Chaim$ sudo cp -r virtualenv-15.1.0 /usr/local/virtualenv3
编辑第一行最后加个“3”，启动python3
Chaim:Downloads Chaim$ sudo vi /usr/local/virtualenv3/virtualenv.py
Chaim:Downloads Chaim$ sudo ln -s /usr/local/virtualenv2/virtualenv.py /usr/sbin/virtualenv2
ln: /usr/sbin/virtualenv2: Operation not permitted
链接不允许建在/usr/sbin目录下，那就建到/usr/local/bin目录下吧
Chaim:Downloads Chaim$ sudo ln -s /usr/local/virtualenv2/virtualenv.py /usr/local/bin/virtualenv2
Chaim:Downloads Chaim$ sudo ln -s /usr/local/virtualenv3/virtualenv.py /usr/local/bin/virtualenv3
进入项目目录，执行如下命令，即切换到一个新的python环境：
Chaim:electrum Chaim$ virtualenv3 env
Using base prefix '/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6'
New python executable in /Users/Chaim/Documents/workspace/electrum/env/bin/python3
Also creating executable in /Users/Chaim/Documents/workspace/electrum/env/bin/python
Installing setuptools, pip, wheel...done.
Chaim:electrum Chaim$ source env/bin/activate
(env) Chaim:electrum Chaim$
注意前面是env，切换到本项目的python环境了
用virtualenv的确好用，python不可不知啊！