drwxr-xr-x 2 user   www       4096 Sep 28 15:05 my_app_dir

set :use_sudo, true
set :sudo, 'sudo su - user'  # fails due to bad su syntax, -c is inserted after user
set :sudo, 'sudo -u user'  # fails because it's not set up
set :sudo, 'sudo su - user -c' # also bad syntax
set :sudo_prompt, ''