Which directories should be owned by root?

I Installed Ubuntu base and it boots to #, then I switch to root by doing su - . but I cannot modify any files as root, for instance, when I try to edit and save /etc/hostname , nano complains that it is a read-only filesystem.

I am guessing that during the installation I should have chowned the relevant directories under / like this:

Quote:

chown -R root:root /bin /etc ...

Now there are a bunch of directories under / :

Quote:

bin boot dev etc home lib lib32 lib64 libx32 lost+found media mnt opt proc root run sbin srv sys tmp usr var

which ones should I set to be owned by root? should I also own the root dir like this:

Quote:

chown root:root /

I also cannot modify any files under /home/user/ when I do su user ... should I do:

Code:chown -R user:user /home/user/
Or should I just do this:

Quote:

chown -R root:root / chown -R user:user /home/user