When we do rm -rf * why we do not delete . and ..?

Question

I am just curious. Is there a save guard there? . and .. is a "subdirectory" of the directory we are deleting right?

I know it's not a subdirectory but linux treat it as a file with directory property.

Answer 1

This is not a part of rm, but a part of your shell. * is a glob which your shell expands and passes to rm in the form of arguments (rm never sees a literal *, unless the glob didn't match anything, in which case a literal * is passed). Standard * globs do not expand to include filenames beginning with a dot, which includes . and ... For example:

$ tee foo bar baz .foo .bar .baz < /dev/null
$ echo *
bar baz foo
$ echo .*
. .. .bar .baz .foo

Answer 2

I guess that's how 'rm' is designed.
suppose that 'rm -rf *' deletes .., then using this command on any directory will delete the entire filesystem, it's like domino effect.
why not delete ., when a user use this command inside a directory, most likely he just want to delete everything inside the directory but not the directory itself. if the dir itself gets deleted, it would surprise the user!