Correct the misunderstanding of ctime for some Linux beginners

Correct some misunderstandings of ctime for Linux beginners in order to distinguish ctime from mtime when they first come into contact with ctime. The mistake is that ctime only changes when the file or directory permissions change, A big mistake! After my own experiments, I have made a lot of google documents, which are summarized as follows: 1) when the file is read-only, it affects atime 2) when the file content is modified, including creating and updating both mtime and ctime 3) when modifying file attributes (chattr, chmod, chown, etc.), you only need to change the ctime and remember it.