User Permission on USB Stick

[Zach]

Since FAT has no permissions mechanism of its own, the linux kernel enforces
permissions based on the mount options.  Usually when a FAT filesystem is
mounted it will be mounted with a particular UMASK.  This means that all
permissions are enabled for every file created except those permissions
specified in the UMASK.  I think you can't even change permissions with
chmod.  This is just a limitation of the FAT filesystem.

As others have mentioned ext2/ext3 is an option where permissions are
important.  These more advanced filesystems also support features like
symlinks and user & group ownership.  However the notion of ownership causes
its own problems with usb flash drives, because if you use it to share files
between computers, if your user IDs and group IDs are not the same on all
computers, then you will have trouble reading/writing/deleting files.  You
may find yourself having to use root/sudo to set permissions & ownership
when moving files back and forth.  That can be a hassle.  To my knowledge
there aren't any mount options for ext2 that will flatten permissions to,
say 777 for directories & 666 for files.

On 12/7/05, Ashwani Jain <ashwani at gisil.com> wrote:
>
> Hi
>
> I am using Ubuntu 5.10.  When I plug in my USB Stick (Kingston 256MB), it
> gets mounted and now we can cut/copy/paste files on and off it.  But the
> problem is that when I copy file form my pc to usb stick it changes it file
> permission.  e.g. I copied a file from my desktop file permission for that
> was 644 and after it got copied to usb stick, on usb stick its file
> permission were 700, when I copied a file carrying file permission 777 after
> it got copied to usb stick its file permission changed to 744.
>
> Why so happens, kindly help.
>
>
>   Thanks & regards
>
> Ashwani Jain
> Systems Administrator
> GISIL, 10th Floor, Tower A
> Signature Towers
> South City 1
> Gurgaon 121001
> Haryana, INDIA
> Handphone: +91-9811084143
> Fax : +91-124-5071700
> Office: +91-124-5071600 ext 202
> WEB:  http://www.gisil.com
> --
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> ubuntu-users at lists.ubuntu.com
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>
>
>


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