Exception:
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/basecommand.py", line 215, in main
status = self.run(options, args)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/commands/install.py", line 342, in run
prefix=options.prefix_path,
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_set.py", line 778, in install
requirement.uninstall(auto_confirm=True)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_install.py", line 754, in uninstall
paths_to_remove.remove(auto_confirm)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/req/req_uninstall.py", line 115, in remove
renames(path, new_path)
File "/Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg/pip/utils/__init__.py", line 267, 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-9.0.1-py2.7.egg/EGG-INFO/PKG-INFO'
You are using pip version 9.0.1, however version 19.1.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
在Mac下使用pip更新一個Python庫時提示pip版本過低，底部命令行中顯示需要升級，升級命令為：You should consider upgrading via the 'pip install --upgrade pip' command.
安裝給出的命令輸入：pip install --upgrade pip；結果執行后，還是報同樣的錯誤。
重試N次后，發現還是執行失敗。
最后上網查找后，才發現是權限問題，修改執行命令為：sudo pip install --upgrade pip
結果執行成功啦，普天同慶哦~