hi, May I know a correct settings for ext2, or ext3 filesystem, when files are written into a directory, or a directory is created under there, no files are allowed to be deleted anymore. I think using chattr to set correct permission, I tried " chattr +a a-dir", the a-dir is owned by a normal user, the normal user can only write zero size file into that directory, so I have no idea what's the correct solution for me?