Ubuntu – Default filesystem permissions and access rights in 12.04

You could use ACL. To set up ACL for Ubuntu 10.10, first mount the file systems with the acl option in /etc/fstab.

sudo vim /etc/fstab

UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx / ext4 defaults,acl 0 1

sudo mount -o remount,acl /

Then make a group to which a user may belong for this purpose.

sudo groupadd developers
sudo usermod -a -G developers $username

The user needs to log out and in again to become a member of the developers group.

Of course, do not do this if you have content in the /var/www directory that you want, but just to illustrate setting it up to start:

sudo rm -rf /var/www
sudo mkdir -p /var/www/public
sudo chown -R root.developers /var/www/public
sudo chmod 0775 /var/www/public
sudo chmod g+s /var/www/public
sudo setfacl -d -m u::rwx,g::rwx,o::r-x /var/www/public

Then replace references to "/var/www" with "/var/www/public" in a config file and reload.

sudo vim /etc/apache2/sites-enabled/000-default
sudo /etc/init.d/apache2 reload

If we wanted to restrict delete and rename from all but the user who created the file:

sudo chmod +t /var/www/public

This way, if we want to create directories for frameworks that exist outside the Apache document root or maybe create server-writable directories, it's still easy.

Apache-writable logs directory:

sudo mkdir /var/www/logs
sudo chgrp www-data /var/www/logs
sudo chmod 0770 /var/www/logs

Apache-readable library directory:

sudo mkdir /var/www/lib
sudo chgrp www-data /var/www/lib
sudo chmod 0750 /var/www/lib

The chown command is to change user and group ownership, to change permissions, you need chmod. So, once you have set the group ownership to pandya using chown as you have, change the permissions to give the group write access:

chmod -R g+w /media/pandya/Ext4/

From man chmod:

The format of a symbolic mode is [ugoa...][[+-=][perms...]...], where perms is either zero or more letters from the set rwxXst, or a single letter from the set ugo. Multiple symbolic modes can be given, separated by commas.

A combination of the letters ugoa controls which users' access to the file will be changed: the user who owns it (u), other users in the file's group (g), other users not in the file's group (o), or all users (a). If none of these are given, the effect is as if a were given, but bits that are set in the umask are not affected.

The operator + causes the selected file mode bits to be added to the existing file mode bits of each file; - causes them to be removed; and = causes them to be added and causes unmentioned bits to be removed

-R, --recursive

change files and directories recursively

So, g+w means "give users that belong to the file's group write access" and -R means apply to all files and subdirectories recursively.