Let's assume that I have a webhosting server running on my ubuntu 13.04 system. For each customer I get that wants to host a website on my server I create a user and add it to a group called 'customers'. All of these customers get a private folder in my /home/ folder, in which there is a folder tree that should not be deleted. So let's say that one of my customers' name is bob. He will get /home/bob/ as his private folder, but that folder should also contain a folder tree like this:

/home/bob/

     |

     |-> /www/

         |

         |-> /bobsdomain.com/

         |              |

         |              |-> /public_html/

         |              |-> /cgi_bin/

         |

         |-> /bobsotherdomain.com/

                        |

                        |-> /public_html/

                        |-> /cgi_bin/

Bob should obviously be the owner of /home/bob because otherwise bob couldn't create or delete files and folders inside his home folder. However, everything between /www/ and /public_html/ or /cgi_bin/ should never be removed. Everything from /public_html/ or /cgi_bin/ and down should be bob's choice wether he wants to delete it or not.

In order to do this, could I just set the folders between /www/ and /public_html/ or /cgi_bin/ as property of root, or would that cause bob being unable to add files to the /public_html/ and /cgi_bin/ folders?

If this is not possible, in what other way should I do this?