I have a folder (which is owned by another user but the same group) and I want to view it's contents, but I always get the following error message:

```
"ls: cannot open directory .: Permission denied"

```

But the group has rwx-permissions!

Eg:

* folder */var/log/somefolder* is owned by `www-data:www-data`
* user `user1` belongs to group `www-data` (but this is not the main-group).

Which permissions do I have to set, that `user1` is allowed to view the folders contents and write to it?