Question

On ubuntu 10.04.4 server, I did this:

sudo mkdir -p /data/somedir
sudo chown -R www-data.www-data /data/somedir
sudo chmod -R g+w /data/somedir
sudo usermod -a -G www-data john ##john is current login user.

. With these operations done, I suppose to have write permission in /data/somedir. But when I did this:

echo "123" > /data/somedir/123

, I got:

-bash: /data/somedir/123: Permission denied

The ls -l output:

$ ls -l /data/
total 4
drwxrwxr-x 2 www-data www-data 4096 2012-04-24 22:30 somedir

Question is: why? Is there something I still need to do after that?

Answer 1

Changes made with usermod only take effect on following logins; your existing login session does not yet have the www-data group, as you can verify with id. It is not easy to alter the identity of running processes (newgrp might work); the easiest way to deal is to log out and back in.