CentOS - Jan 2010 - directory permissions

Hi,

I have changed directory ownership permissions recursively such that
it is owned by username:groupname , where groupname is not the default
group, i.e., username. However, when a user creates a new file the
default permissions are again username:username.

How can I give  ownership permissions on a particular directory so
that any files created in that directory will always have specifc
username:groupname permissions?
Also is there any option that would allow only owner to delete files,
even though group has rwx permissions?

Thanks,
CS.

Carlos Santana wrote:
> How can I give  ownership permissions on a particular directory so
> that any files created in that directory will always have specifc
> username:groupname permissions?
make the directory setgid chmod g+s
> Also is there any option that would allow only owner to delete files,
> even though group has rwx permissions?
Perhaps via ACLs..

nate

On Tue, 12 Jan 2010, Carlos Santana wrote:
> Hi,
>
> I have changed directory ownership permissions recursively such that 
> it is owned by username:groupname , where groupname is not the 
> default group, i.e., username. However, when a user creates a new 
> file the default permissions are again username:username.
>
> How can I give ownership permissions on a particular directory so 
> that any files created in that directory will always have specifc 
> username:groupname permissions?
chmod 2775 /your/directory

This will assign group ownership of any files created in 
/your/directory to the group that owns that directory.

It won't, however, change user ownership. Allowing that sort of 
operation would be a great avenue for a denial-of-service attach on 
any filesystem with quotas.
> Also is there any option that would allow only owner to delete 
> files, even though group has rwx permissions?
chmod 3775 /your/directory

This combines the 2775 trick mentioned above with an o+s operation. 
Setting the "sticky bit" on the all-users permissions allows only 
owners to dispose of files. See the permissions on /tmp or /var/tmp 
for an example.

-- 
Paul Heinlein <> heinlein at madboa.com <> http://www.madboa.com/