That post was a really informative one, but I think you’ll want to reorder it. All the “easy-to-read” stuff should be at first and not in the end, While all the endless lists and BITS stuff can wait to the end of the article. I’m hope you’re still editing this post and at least reordering it.

I still have some question:

As a webmaster I have to understand files permissions to secure my web server and my site, BUT did I have to understand also all the filetypes stuff? (like under Bitmasking to determine Filetype etc.)

In your article you wrote the following about the S_ISVTX :

Prevent unprivileged users from removing or renaming a file in a directory unless they own the file or the directory; this is called the restricted deletion flag for the directory, and is commonly found on world-writable directories like /tmp.
For regular files on some older systems, save the program’s text image on the swap device so it will load more quickly when run; this is called the sticky bit.

What does that mean?

There is a really good site that explain chmod & files permissions

Thanks,
dvb

max