我正在尝试在iMac上升级点子，但我一直收到权限拒绝错误。我是管理员，所以我不知道自己做错了什么。

iMac:~ me$ pip install --upgrade pip
    You are using pip version 6.0.8, however version 7.1.2 is available.
    You should consider upgrading via the 'pip install --upgrade pip' command.
    Collecting pip from https://pypi.python.org/packages/py2.py3/p/pip/pip-7.1.2-py2.py3-none-any.whl#md5=5ff9fec0be479e4e36df467556deed4d
      Downloading pip-7.1.2-py2.py3-none-any.whl (1.1MB)
        100% |################################| 1.1MB 181kB/s 
    Installing collected packages: pip
      Found existing installation: pip 6.0.8
        Uninstalling pip-6.0.8:
          Exception:
          Traceback (most recent call last):
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/basecommand.py", line 232, in main
              status = self.run(options, args)
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/commands/install.py", line 347, in run
              root=options.root_path,
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/req/req_set.py", line 543, in install
              requirement.uninstall(auto_confirm=True)
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/req/req_install.py", line 667, in uninstall
              paths_to_remove.remove(auto_confirm)
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/req/req_uninstall.py", line 126, in remove
              renames(path, new_path)
            File "/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/pip/utils/__init__.py", line 316, in renames
              shutil.move(old, new)
            File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 300, in move
              rmtree(src)
            File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 247, in rmtree
              rmtree(fullname, ignore_errors, onerror)
            File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 252, in rmtree
              onerror(os.remove, fullname, sys.exc_info())
            File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 250, in rmtree
              os.remove(fullname)
          OSError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/pip-6.0.8-py2.7.egg/EGG-INFO/dependency_links.txt'

我不知道我在这里做错了什么，因为升级似乎很简单。

谢谢，