newbie's question on file permission

[Nils Kassube]

Zhengguo Xu wrote:
> I have a file, lets say 'biology.ppt' and it has permission as follows
> and i am the owner and it belongs to group 'root'
>
> -rwx------
>
> i want to change it to group, say, 'test', and give permissions to
> everyone to read and write and execute, what's wrong when I run the
> following command?
>
> sudo chgrp test biology.ppt
> sudo chmod 777 biology.ppt
>
> nothing happened when i run these commands and i tried them with and
> without sudo. the file still has the permission -rwx------ and root is
> still the group.
>
> if it matters, the file is on a usb disk mounted in /media

Yes, it matters if the file system is FAT32 or NTFS which is the usual 
file system for USB disks. FAT32 or NTFS don't know about Unix 
permissions and therefore you can't change them.


Nils