immutability of directories

gistfile1.txt

root@willbell:~# ls
root@willbell:~# mkdir lol
root@willbell:~# cd lol/
root@willbell:~/lol# ls
root@willbell:~/lol# touch banana
root@willbell:~/lol# touch frog
root@willbell:~/lol# chattr +i banana
root@willbell:~/lol# echo asdasdasd >> banana
-bash: banana: Permission denied
root@willbell:~/lol# echo asdasdasd >> frog
root@willbell:~/lol# cd ..
root@willbell:~# ls
lol
root@willbell:~# chattr +i lol
root@willbell:~# cd lol/
root@willbell:~/lol# ls
banana  frog
root@willbell:~/lol# echo asdasdasd >> frog
root@willbell:~/lol# cd ..
root@willbell:~# ls
lol
root@willbell:~# mv lol haha
mv: cannot move `lol' to `haha': Operation not permitted
root@willbell:~#