Why does my find command seem to execute twice? [duplicate] - shell

Question

This is the contents of the directory I'm working with:
misha#hp-laptop:~/work/c/5$ ls -l
total 8
-rw-rw-r-- 1 misha misha 219 May 20 15:37 demo.c
drwxrwxr-x 2 misha misha 4096 May 20 16:07 folder
-rw-rw-r-- 1 misha misha 0 May 20 16:06 test
Now I would like to remove everything from this directory except for the file demo.c. Here's the command I've come up with:
find . ! \( -name demo.c -o -name . \) -exec rm -Rf {} \;
It does exactly what you'd think it would do (meaning, the file test and the directory folder are gone), but at the same time it also displays the following error message:
find: `./folder': No such file or directory
Why do you think that is?

Answer 1

it also displays this error message:
find: `./folder': No such file or directory
Why is that?
Because find recognizes ./folder as a directory when it first reads directory ., before considering whether it matches the find criteria or performing any action on it. It does not recognize that the action will remove that directory, so after performing the action, it attempts to descend into that directory to scan its contents. By the time it does that, however, the directory no longer exists.
There are multiple ways to address the problem. One not yet mentioned is to use the -prune action. This tells find not to descend into directories that match the tests:
find . ! \( -name demo.c -o -name . \) -exec rm -Rf {} \; -prune
That will serve nicely here, and it also has applications in areas where you are not deleting the directory and you do not want to limit the search depth.
Additionally, another way to avoid affecting . would be to make use of the fact that find accepts multiple base paths to test, that these can designate regular files if you wish, and that during pathname expansion any leading . in a filename must be matched explicitly. If, as in your case, there are no dotfiles in the target directory (other than . and ..), then you can accomplish your objective like this:
find * ! -name demo.c -exec rm -Rf {} \; -prune

Answer 2

You can change your find command to this:
find . -mindepth 1 -not -name demo.c -delete
-mindepth 1 ensure that you don't select DOT
-delete will delete all files and directories

Answer 3

#before
ls -lrt
total 4
-rw-rw-r-- 1 user super 0 May 20 09:14 demo.c
drwxrwxr-x 2 user super 4096 May 20 09:14 folder/
-rw-rw-r-- 1 user super 0 May 20 09:14 test
#Command
ls -1 | grep -v demo.c |xargs rm -rf
#After
ls -lrt
total 0
-rw-rw-r-- 1 user super 0 May 20 09:14 demo.c