newbie's question on file permission

[Ansgar Burchardt]

Hi,

"Zhengguo Xu" <tworiversfolk at gmail.com> writes:

> 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

Not all file systems support storing ownership information and
permissions.  What file system are you using on the USB disk [1]?

USB disks are often used together with FAT32 which does not support
permissions.  Linux then uses permissions based on flags passed to the
mount command.

Regards,
Ansgar

[1] Running `mount' lists all (mounted) file systems and their type

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