安装 mysqldb （pip3 install Flask-MySQLdb）报错 EnvironmentError: mysql_config not found ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.
或者出现 error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
解决方案：
参考Github上的答案（https://github.com/scrapy/scrapy/issues/2115#issuecomment-231849637），成功解决。
with Python 3, you'll need
sudo apt-get install python3 python-dev python3-dev build-essential libssl-dev libffi-dev libxml2-dev libxslt1-dev zlib1g-dev python3-pip
with Python 2, you'll need
sudo apt-get install python-dev build-essential libssl-dev libffi-dev libxml2-dev libxslt1-dev zlib1g-dev python-pip