One of the things which encouraged me towards less "trendy" software is that it hasn't gotten totally caught up in ai-hype. Books written before the slop-pocalypse are really useful, and turn out to be a nice way to soothe my inner nerd while I continue to learn new (to me) things.
As an example, the venerable "Unix Power Tools" has a wonderful chapter on the vi editor:
https://docstore.mik.ua/orelly/unix/upt/part05.htm
Enjoy!
As I continue to escape into the obscuria of elder text mangling tools, I've found myself enjoying the opportunity to act as the local #viTips fairy when I find anything interesting or useful.
And here's another cool vi trick I found!
You can append to a file rather than overwriting it by prefixing >> to the filename:
:w >>appendtofilename
This can work on parts of a buffer by prefixing line numbers or ranges:
2,+1w >>appendfilename
This appends the second and subsequent line.
cc
-Delete the text of the current line and start typing in its place
C
-Delete from the current character to the end of the line and start typing there
R
-Start typing. Any typed text replaces what is already there on the line starting at the current character
('c' is composable and so there are many variations of it to drop into editing, but I haven't done composable things yet 
)
Just hit 'i', right? Not just that.
i
-Insert before the current character
a
-Insert after the current character
o
-Open a line below this one and start inserting there
O
-Open a line above this one and start inserting there
A
-Start adding text at the end of the current line
I
-Start adding text at the beginning of the current line
(This one can be a little weird, it does it *after* any indentation)
(More coming)
You can specify multiple files when starting vi
vi foo bar baz
This drops you into vi editing "foo". How do you get to the other files?
:n
:next
- Go to the next file
:rew
:rewind
- Go back to the beginning of the list
Both will complain if you have unsaved changes. Add '!' to the end to force it.
When editing multiple files, vi will complain if you try to quit out without looking at all the files. Repeating the quit command will exit.
Russ Sharek
XCondE
pamela 
Combat Unicorn