setting file permissions in linux

Had a problem recently where I needed to share sftp uploads to linux amongst different users.

Step 1:
Make sure the users primary group is the shared group
newgrp groupname
http://tldp.org/LDP/intro-linux/html/sect_03_04.html

Step 2:
You need to know about umask.
You can edit it via .bashrc, but that wont help you out for sftp


Step 3:
Modify sshd_config, so that it sets umask correctly for the sftp session
http://jeff.robbins.ws/articles/setting-the-umask-for-sftp-transactions