Linux directory permissions

I have a folder created by root and I want to be able to add permissions to a usergroup so they can move around the files etc.

I did the following:

chgrp -R developers testdir

The file owner is now root and the group owner is developers. Why can a user in developers not make changes yet?

For standard unix permissions you must always consider, the owner (user/group/other), permission bits, and the umask. The combination of these things are what describe your effective rights, and the permissions of new items.

• chown/chgrp set the ownership.
• chmod set the permssions
• the umask is part of each users environment and depending on how it is set, it will remove permission bits.

So if you want to create a shared folder for a group you usually need to do something like this.

• Create a new group (projectgrp) and add the users to that group.
• Change the group ownership of everything under your project folder to projectgrp
• Change the permissions of all the folders to 2775
• Change all the files to 0664.
• Change the umask for all users to 0002

Of course there are other things you can do with ACLs that are a lot more complex for the sysadmin, but can make things easier for the end user.

Because the group doesn't have suitable permissions on the files and directories on and within testdir.