Vim file refresh

  question, vim

I have a file that was first opened by vim and then opened by UE, and it was modified in the UE.
If you want to know whether there is a corresponding command in vim, you can refresh the opened document to the latest content.
Another: vimli: what does the r command mean?
Thank you!

:e!

R means read, read the contents of another file and insert it into the current position. Details: help read