Execute o comando abaixo e cole aqui a resposta:
ls -l /etc/apt
Deu isso!!
total 52
drwxr-xr-x 2 root root 4096 2009-03-25 00:42 apt.conf.d
-rw------- 1 root root 0 2008-10-29 20:54 secring.gpg
-rw-r--r-- 1 root root 3226 2009-04-03 10:51 sources.list
-rw-r--r-- 1 root root 4832 2009-04-03 01:55 sources.list~
drwxr-xr-x 2 root root 4096 2009-03-23 19:46 sources.list.d
-rw-r--r-- 1 root root 3264 2009-04-03 10:51 sources.list.save
-rw------- 1 root root 1200 2009-03-09 16:05 trustdb.gpg
-rw-r--r-- 1 root root 8274 2009-03-09 16:05 trusted.gpg
-rw-r--r-- 1 root root 8274 2009-03-09 16:05 trusted.gpg~