$ gksudo -u -www-data krusader
No protocol specified
krusader: cannot connect to X server :0.0

DocumentRoot /home/user/my-project/my-document-root

xhost +SI:localuser:uname
gksudo -u uname -l "firefox"
xhost -SI:localuser:uname

$ sudo su www-data
[sudo] password for <your username>: [enter your password]
$ whoami
(you should see www-data here)

/var/www$ sudo chown -R [your-username]:[your-group] *
/var/www$ find . -type d -exec chmod a+rx {} ;
/var/www$ find . -type f -exec chmod a+r {} ;

xhost +SI:localuser:<user-to-run-as>

sudo su - <user-to-run-as>

krusader

sudo adduser $USER www-data

sudo chown www-data:www-data /var/www/file
chmod g+w /var/www/file