The command you want is :e (short for :edit). If you use :edit! it will discard local changes and reload.
You can also have vim do this automatically with set autoread in your vimrc.
https://www.jianshu.com/p/be2660714986
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google上搜索了一下，说是当前文件夹被写入了root权限，所以用普通用户无法编辑，只要将当前文件夹的权限改变一下即可
sudo chown -R $USER <directory_project>
例如我的是这样解决的
cd <你项目所在的目录>
sudo chown -R mac ./项目文件夹名