Python 安装beautifulsoup4库和pip时在终端中被拒绝的权限

尝试使用Sudo和Sudo-I提示终端输入密码，即使在输入密码后，它也不会运行

Last login: Fri Jan  4 08:48:43 on ttys000

Kumars-MacBook-Air:~ getyoteam$ pip install BeautifulSoup4
-bash: pip: command not found.

Kumars-MacBook-Air:~ getyoteam$ easy_install pip
error: can't create or remove files in install directory

The following error occurred while trying to add or remove files in 
the installation directory:
[Errno 13] Permission denied: '/Library/Python/2.7/site-packages/test-easy-install-906.pth'
The installation directory you specified (via --install-dir, --prefix, or
the distutils default setting) was:
/Library/Python/2.7/site-packages/
Perhaps your account does not have write access to this directory? If the 
installation directory is a system-owned directory, you may need to sign in
as the administrator or "root" account.  If you do not have administrative
access to this machine, you may wish to choose a different installation
directory, preferably one that is listed in your PYTHONPATH environment
variable.

For information on other options, you may wish to consult the 
documentation at:

  https://pythonhosted.org/setuptools/easy_install.html

Please make the appropriate changes for your system and try again.

Kumars-MacBook-Air:~ getyoteam$ 

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要添加beautifulsoup4库，需要执行哪些操作

这个场景正是构建虚拟环境的目的。激活代码所在的一个，然后重试