Why does 'rmdir -p --ignore-fail-on-non-empty' fail when encountering $HOME?

Question

Please consider the following commands:

cd /
mkdir -p ~/a/b
touch ~/a/content
# Removes dir 'b' and stops at 'a' because it's non-empty.
# (This is the expected behavior.)
rmdir -p --ignore-fail-on-non-empty ~/a/b

rm ~/a/content
mkdir -p ~/a/b
# Fails with error: "rmdir: failed to remove directory '/home/myhome'".
rmdir -p --ignore-fail-on-non-empty ~/a/b

Why does rmdir fail at the last step? Why does it try to delete the non-empty $HOME instead of stopping?

Answer 1

Here is what man rmdir says:

--ignore-fail-on-non-empty

ignore each failure that is solely because a directory is non-empty

i.e. a failure to remove a directory due to some other error, aside from it's being empty, will still be reported.

And as regular users normally do not have enough permissions to modify /home (including removal of their own home directory), the rmdir just hits a "Permission denied" error, when invoked like that.

You can easily confirm this by attempting:

rmdir ~

which will result in:

rmdir: failed to remove '/home/youruser': Permission denied