首先安装pip: sudo apt-get install python-pip
接着安装scrapy依赖包：
1、 sudo apt-get install python-dev
2、sudo apt-get install libevent-dev
3、 sudo apt-get install libssl-dev
最后执行scrapy安装命令
--sudo pip install scrapy（python2的安装命令）
--sudo pip3 install scrapy（python3的安装命令）
安装完后，可以输入scrapy version查看是否安装成功
如果出现了以下的错误信息，需要执行这条命令：
--sudo pip3 install service_identity --force --upgrade
:0: UserWarning: You do not have a working installation of the service_identity module: 'cannot import name 'opentype''. Please install it from and make sure all of its dependencies are satisfied. Without the service_identity module, Twisted can perform only rudimentary TLS client hostname verification. Many valid certificate/hostname mappings may be rejected.
