下载解压

wget https://www.crummy.com/software/BeautifulSoup/bs4/download/4.5/beautifulsoup4-4.5.1.tar.gz
tar -xvzf beautifulsoup4-4.5.1.tar.gz

安装

cd /beautifulsoup4-4.5.1/
python3 setup.py install

安装lxml

pip3 install lxml