demas@demas:~$ sudo rm -rf /etc/rvmrc /etc/profile.d/rvm.sh /usr/local/rvm
demas@demas:~$ curl -L https://get.rvm.io | bash -s stable
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 184 100 184 0 0 218 0 --:--:-- --:--:-- --:--:-- 308
100 13145 100 13145 0 0 12150 0 0:00:01 0:00:01 --:--:-- 12150
mkdir: cannot create directory `/usr/local/rvm': Permission denied
我该如何解决?