在 Linux 下安装 mysqlclient，如果是选择直接安装的话，一般会报如下错误，
(djenv) handsome@fzq:~$ pip install mysqlclient -i https://pypi.doubanio.com/simple/
Looking in indexes: https://pypi.doubanio.com/simple/
Collecting mysqlclient
Downloading https://pypi.doubanio.com/packages/ec/fd/83329b9d3e14f7344d1cb31f128e6dbba70c5975c9e57896815dbb1988ad/mysqlclient-1.3.13.tar.gz (90kB)
100% |████████████████████████████████| 92kB 2.1MB/s
Complete output from command python setup.py egg_info:
/bin/sh: 1: mysql_config: not found
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/tmp/pip-install-y16_5477/mysqlclient/setup.py", line 18, in <module>
metadata, options = get_config()
File "/tmp/pip-install-y16_5477/mysqlclient/setup_posix.py", line 53, in get_config
libs = mysql_config("libs_r")
File "/tmp/pip-install-y16_5477/mysqlclient/setup_posix.py", line 28, in mysql_config
raise EnvironmentError("%s not found" % (mysql_config.path,))
OSError: mysql_config not found
----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-install-y16_5477/mysqlclient/
解答方案， 一般来说安装一个依赖即可
(djenv) handsome@fzq:~$ sudo apt install libmysqlclient-dev
安装完依赖之后，再次执行pip install mysqlclient -i https://pypi.doubanio.com/simple/ 即可成功安装
