由于pip19.2.3版本诸多问题， 决定卸载， 结果发现根本无法卸载， 提示以下错误信息：
C:\Users\abc>python -m pip uninstall pipUninstalling pip-19.2.3:Would remove:c:\program files\python38\lib\site-packages\pip-19.2.3.dist-info\*c:\program files\python38\lib\site-packages\pip\*c:\program files\python38\scripts\pip.exec:\program files\python38\scripts\pip3.8.exec:\program files\python38\scripts\pip3.exeProceed (y/n)? yERROR: Exception:Traceback (most recent call last):File "C:\Program Files\Python38\lib\shutil.py", line 781, in moveos.rename(src, real_dst)PermissionError: [WinError 5] 拒绝访问。: 'c:\\program files\\python38\\lib\\site-packages\\pip-19.2.3.dist-info\\' -> 'C:\\Users\\abc\\AppData\\Local\\Temp\\pip-uninstall-flz7sdgb'During handling of the above exception, another exception occurred:Traceback (most recent call last):File "C:\Program Files\Python38\lib\site-packages\pip\_internal\cli\base_command.py", line 188, in mainstatus = self.run(options, args)File "C:\Program Files\Python38\lib\site-packages\pip\_internal\commands\uninstall.py", line 74, in rununinstall_pathset = req.uninstall(File "C:\Program Files\Python38\lib\site-packages\pip\_internal\req\req_install.py", line 831, in uninstalluninstalled_pathset.remove(auto_confirm, verbose)File "C:\Program Files\Python38\lib\site-packages\pip\_internal\req\req_uninstall.py", line 388, in removemoved.stash(path)File "C:\Program Files\Python38\lib\site-packages\pip\_internal\req\req_uninstall.py", line 277, in stashrenames(path, new_path)File "C:\Program Files\Python38\lib\site-packages\pip\_internal\utils\misc.py", line 402, in renamesshutil.move(old, new)File "C:\Program Files\Python38\lib\shutil.py", line 793, in movermtree(src)File "C:\Program Files\Python38\lib\shutil.py", line 731, in rmtreereturn _rmtree_unsafe(path, onerror)File "C:\Program Files\Python38\lib\shutil.py", line 609, in _rmtree_unsafeonerror(os.unlink, fullname, sys.exc_info())File "C:\Program Files\Python38\lib\shutil.py", line 607, in _rmtree_unsafeos.unlink(fullname)PermissionError: [WinError 5] 拒绝访问。: 'c:\\program files\\python38\\lib\\site-packages\\pip-19.2.3.dist-info\\entry_points.txt'
分析了下， 应该是C:\Program Files\Python38\Lib\site-packages\pip-19.2.3.dist-info这里面出现了问题，而且应该是权限的问题， 懒得处理，
于是直接把这个文件夹删除了， 再次使用unstall命令， 得到如下结果：
C:\Users\abc>python -m pip uninstall pipWARNING: Skipping pip as it is not installed.
直接找不到了， 于是尝试安装老版本pip
C:\Users\abc>python -m pip install pip==18.0 --userLooking in indexes: /simpleCollecting pip==18.0Downloading /packages/5f/25/e52d3f31441505a5f3af41213346e5b6c221c9e086a166f3703d2ddaf940/pip-18.0-py2.py3-none-any.whl (1.3MB)|████████████████████████████████| 1.3MB 226kB/sInstalling collected packages: pipSuccessfully installed pip-18.0WARNING: You are using pip version 18.0, however version 19.3.1 is available.You should consider upgrading via the 'python -m pip install --upgrade pip' command.
安装成功， 实验pip安装
C:\Users\abc>pip install xlrd --userLooking in indexes: /simpleCollecting xlrdDownloading /packages/b0/16/63576a1a001752e34bf8ea62e367997530dc553b689356b9879339cf45a4/xlrd-1.2.0-py2.py3-none-any.whl (103kB)100% |████████████████████████████████| 112kB 937kB/sInstalling collected packages: xlrdSuccessfully installed xlrd-1.2.0You are using pip version 18.0, however version 19.3.1 is available.You should consider upgrading via the 'python -m pip install --upgrade pip' command.C:\Users\abc>
ok , 没什么问题
