$ whoami
user
$ ls -l /var/www/somedir/
total 7804
-rw-rwxr--+ 1 user-group user 3794560 июл 26  2013 TeamViewerQJ_ru.exe
-rw-rwxr--+ 1 user-group user 4192096 июн 18  2013 TeamViewerQS_ru.exe
$ ls -l /var/www/
total 156
...
drwxrwxr-x+ 2 user-group user  4096 июл 26  2013 somedir
...
$ groups user
user : user ...
$ groups user-group
user-group : user ...

$ touch /var/www/somedir/test.txt
touch: cannot touch '/var/www/somedir/test.txt': Permission denied