newbie's question on file permission

[POWERS, ZACK]

Hi,
The reason permissions don't change on your USB stick is because your
USB disk is formatted in a filesystem that does not support POSIX
style file permissions. If its FAT16 or FAT32, which it is most likely
is, it doesn't support any type of file permissions. To solve this
issues you will have to reformat your USB disk to a POSIX compliant
filesystem (NTFS would be the best choice for compatibility with
Windows).


-----Original Message-----
From: ubuntu-users-bounces at lists.ubuntu.com on behalf of Zhengguo Xu
Sent: Fri 8/1/2008 2:37 PM
To: Ubuntu User
Subject: newbie's question on file permission
 
Greeting all!

Recently I encounted a strange problem (or it maybe very obvious for
you
guys) while copying files and I'd like to ask a question on file
permission
in linux.

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

i also tried to create some file in my home directory and i can change
it as
i want with the same command.

any help would be greatly appreciated.

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