Linux command line to check the directory's size

Using the I got this message "disk quota exceeded" after try install mongoid. The initial plan available for free accounts on Nitrous provides 750MB storage.

But I was asking myself how could my application in rails, that I just started to code, get all this space used? Try to guess could no help me to solve this problem then I learned this new linux command line to check the directories size:

du -h --max-depth=1 ~/ | sort -n -r

And I understood exactly where the problem was, my .rvm directory was too much big:

405M    /home/action/
222M    /home/action/.rvm
144M    /home/action/.gem
24M     /home/action/.nvm
24K     /home/action/.subversion
15M     /home/action/.vim
8.0K    /home/action/.ssh
1.8M    /home/action/easy_order
0       /home/action/workspace
0       /home/action/.cache

ps: I got this output after remove a ruby version not used

Explaning the command line:

Off-Topic: Please, help me to get more space in Nitrous. You just have to create an account using my link :)