I'm trying to find out the default ownership & permissions for my ubuntu install. I'm also trying to figure out whether the wrong-headed granted of file ownership to the user robert to system files is an irrecoverable error. Is it too complicated to try to undo what I have done for my system and just reinstall?

First, some background. I think I made the wrong command when I was trying to change the permissions on a 2nd ext4 drive which formerly had ubuntu installed on it. I must have inadvertently made changes to my current / directory without realizing it. Symptoms of the problem is that I no longer have sudo access on my current system.

robert@robert-KJ379AA-ABA-a6400f:/$ sudo ls -al

sudo: /etc/sudoers is owned by uid 1000, should be 0

sudo: no valid sudoers sources found, quitting

sudo: unable to initialize policy plugin

I see that "robert" now owns all the files inside /etc: Examples:

drwxr-xr-x   3 robert root    4096 Apr  9 12:27 firefox

drwxr-xr-x   4 robert root    4096 Aug 23  2012 fonts

drwxr-xr-x   3 robert root    4096 Aug 23  2012 foomatic

-rw-r--r--   1 robert root     766 Apr 11 12:39 fstab

-rw-r--r--   1 robert root     664 Apr  9 11:26 fstab~

drwxr-xr-x   2 robert root    4096 Mar 29  2012 fstab.d

-rw-r--r--   1 robert root     664 Apr 11 12:36 fstab.original

-rw-r-----   1 robert fuse     216 Oct 18  2011 fuse.conf

-rw-r--r--   1 robert root    3343 Apr 19  2012 gai.conf

drwxr-xr-x   5 robert root    4096 Aug 23  2012 gconf

Here are the permissions and ownership for the / directory

drwxr-xr-x  25 root   root    4096 May  5 15:26 .

drwxr-xr-x  25 root   root    4096 May  5 15:26 ..

drwxr-xr-x   2 robert root    4096 Apr 10 22:55 bin

drwxr-xr-x   3 robert root    4096 May  5 15:26 boot

drwxr-xr-x   2 robert root    4096 Apr  9 11:30 cdrom

drwxr-xr-x  15 root   root    4560 May  5 17:28 dev

drwxr-xr-x 150 robert root   12288 May  5 17:45 etc

drwxr-xr-x   3 robert root    4096 Apr  9 11:37 home

lrwxrwxrwx   1 robert root      33 May  5 15:26 initrd.img -> /boot/initrd.img-3.2.0-41-generic

lrwxrwxrwx   1 robert root      33 Apr  9 12:26 initrd.img.old -> /boot/initrd.img-3.2.0-40-generic

drwxr-xr-x  22 robert root    4096 Apr 24 16:58 lib

drwxr-xr-x   2 robert root    4096 Apr 24 16:58 lib64

drwx------   2 robert root   16384 Apr  9 11:26 lost+found

drwxr-xr-x   5 root   root    4096 May  5 17:28 media

drwxr-xr-x   2 root   root    4096 Apr 19  2012 mnt

drwxr-xr-x   2 root   root    4096 Aug 23  2012 opt

dr-xr-xr-x 198 root   root       0 May  5 12:26 proc

drwx------   8 root   root    4096 Apr 17 02:11 root

drwxr-xr-x  23 root   root     820 May  5 17:43 run

drwxr-xr-x   2 root   root    4096 Apr 24 16:58 sbin

drwxr-xr-x   2 root   root    4096 Mar  5  2012 selinux

drwxr-xr-x   2 root   root    4096 Aug 23  2012 srv

drwxr-xr-x  13 root   root       0 May  5 12:27 sys

drwxrwxrwt  10 root   root    4096 May  5 19:37 tmp

drwxr-xr-x  10 root   root    4096 Aug 23  2012 usr

drwxr-xr-x  14 root   root    4096 May  5 17:26 var

lrwxrwxrwx   1 root   root      29 May  5 15:26 vmlinuz -> boot/vmlinuz-3.2.0-41-generic

lrwxrwxrwx   1 root   root      29 Apr  9 12:26 vmlinuz.old -> boot/vmlinuz-3.2.0-40-generic

drwxrwxr--   1 robert robert  4096 Apr  9 01:37 windows1

Can anyone confirm that "robert" must not own any of these directories just below root? Is there anything here to suggest that the problem may be easy to recover from? If yes, do you have any advice or resources for how to fix this? Thanks.