root@localhost:/etc/writable# ls -l /etc/default/watchdog 
lrwxrwxrwx 1 root root 25 Oct 22 14:03 /etc/default/watchdog -> writable/default/watchdog
# ls -l /etc/writable/
total 20
drwxr-xr-x 2 root root 4096 Oct 22 13:41 default
-rw-r--r-- 1 root root   22 Sep 10 06:52 hostname
-rw-r--r-- 1 root root  127 Sep  9 04:58 localtime
-rw-r--r-- 1 root root    8 Sep  9 04:58 timezone
-rw-r--r-- 1 root root 1126 Oct 17  2014 watchdog.conf