I have an Apache based web site and am trying to allow the user to upload files to a drop box on one machine and then have them transferred to another.  So I form a group for two users: www-data which is the Apache web user and OtagoHarbour which has a key to transfer files from one machine to another.The existence of the group and its members is confirmed thus.OtagoHarbour@WebServer:/var/www$ egrep -i www-OtagoHarbour /etc/groupwww-OtagoHarbour:x:1002:OtagoHarbour,www-dataHowever, this does not appear to give OtagoHarbour group permissions to a group owned by www-data.OtagoHarbour@WebServer:/var/www$ sudo ls -ld dropboxdrwx-wx-wx 2 www-data root 4096 2014-01-20 23:25 dropboxOtagoHarbour@WebServer:/var/www$ sudo chmod g+r dropboxOtagoHarbour@WebServer:/var/www$ sudo ls -ld dropboxdrwxrwx-wx 2 www-data root 4096 2014-01-20 23:25 dropboxOtagoHarbour@WebServer:/var/www$ scp /var/www/dropbox/*.cel 192.168.1.6:/var/www/dropbox/var/www/dropbox/*.cel: No such file or directoryOtagoHarbour@WebServer:/var/www$ sudo chmod o+r dropboxOtagoHarbour@WebServer:/var/www$ scp /var/www/dropbox/*.cel 192.168.1.6:/var/www/dropboxwhatever1.cel                    100%   11MB  11.3MB/s  00:01    whatever2.cel                    100%   11MB  11.2MB/s  00:01    whatever3.cel                    100%   11MB  11.2MB/s  00:01  So, despite www-data and OtagoHarbour being in the same group, g+r does not appear to give OtagoHarbour read access to a group owned by www-data (but o+r does).UpdateOtagoHarbour@WebServer:/var/www$ sudo chgrp -R www-OtagoHarbour /var/www/dropboxOtagoHarbour@WebServer:/var/www$ sudo chmod o-r dropboxOtagoHarbour@WebServer:/var/www$ sudo chmod g+r dropboxOtagoHarbour@WebServer:/var/www$ scp /var/www/dropbox/*.cel 192.168.1.6:/var/www/dropbox/var/www/dropbox/*.cel: No such file or directoryUpdate 2OtagoHarbour@WebServer:/var/www$ ldld: no input filesOtagoHarbour@WebServer:/var/www$ ls -l /var/www/dropbox/*.cells: cannot access /var/www/dropbox/*.cel: No such file or directoryOtagoHarbour@WebServer:/var/www$ ls -l /var/www/dropboxls: cannot open directory /var/www/dropbox: Permission deniedOtagoHarbour@WebServer:/var/www$ 
Putting two accounts in group not giving read access to group members
scp;group;chmod
Users OtagoHarbour and www-data belong to www-OtagoHarbour group but dropbox directory isn't associated to www-OtagoHarbour group but to root.Running commandsudo chgrp -R www-OtagoHarbour /var/www/dropboxshould fix the problem. With this change you don't need to keep the directory world readable.