I use a variant of the simple script below from the Community Ubuntu Documentation described
tar -cvpzf backup.tar.gz --exclude=/backup.tar.gz --exclude=/proc --exclude=/lost+found --exclude=/sys --exclude=/mnt --exclude=/media --exclude=/dev /
I used it again on Ubuntu 12.04 and I saw some files from the /run being skipped by the script. Should the /run directory be added to the excluded directories?
No sure on Ubuntu 12.04 but, on Arch Linux /run is a tmpfs and on my Ubuntu 12.04 where only /var/run exists it is also a tmpfs. So if it is a tmpfs, what I assume, on 12.04 then you can exclude it.
Exclude it. The standard set of directories that I exclude in Linux backup processes are:
and maybe
/var/run