如果没有安装包管理工具就执行
1.首先执行命令：sudo easy_install pip
安装完成后执行命令：pip install beautifulsoup4
然后运行，然后问题来了，居然提示没有权限？？？
Collecting beautifulsoup4
Using cached beautifulsoup4-4.4.0-py2-none-any.whl
Installing collected packages: beautifulsoup4
Exception:
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/basecommand.py", line 223, in main
status = self.run(options, args)
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/commands/install.py", line 299, in run
root=options.root_path,
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/req/req_set.py", line 646, in install
**kwargs
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/req/req_install.py", line 813, in install
self.move_wheel_files(self.source_dir, root=root)
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/req/req_install.py", line 1008, in move_wheel_files
isolated=self.isolated,
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/wheel.py", line 339, in move_wheel_files
clobber(source, lib_dir, True)
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/wheel.py", line 310, in clobber
ensure_dir(destdir)
File "/Library/Python/2.7/site-packages/pip-7.1.0-py2.7.egg/pip/utils/__init__.py", line 70, in ensure_dir
os.makedirs(path)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 157, in makedirs
mkdir(name, mode)
OSError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/beautifulsoup4-4.4.0.dist-info'
这时候输入命令：sudo easy_install beautifulsoup4
进入Python输入：from bs4 import BeautifulSoup
会发现提示：没有这个模块名，那是因为Mac系统自带了Python2.7 你要把beautifulsoup4写到Python3的目录文件里去
命令行输入：pip3 install beautifulsoup4
