Re: Itroductry info on permission issues and implications - where? -was [Re: permissions on a Verbatim USB external drive]
----- Original Message -----
From: Joao Luis Meloni Assirati
To: debian-user@lists.debian.org
Sent: 3/13/2013 7:31:19 PM
Subject: Re: Itroductry info on permission issues and implications - where? -was [Re: permissions on a Verbatim USB external drive]
> João Luis Meloni Assirati wrote:
>> [snip]
>>
>> Since vfat filesystems don't hold UNIX permissions, it has
>> to be mounted with the umask and/or uid, gid options. If it
>> is plugged through USB and you have a mount desktop service
>> communicating with dbus, all should be automatic. However,
>> if User mounts it in a static configuration in fstab, at
>> least the umask must be set. If this is the case, try an
>> fstab line like
>>
>> /dev/sd?? /media/vfat vfat
>> defaults,umask=0007,uid=User,gid=User 0 0
>>
>> which grants permission for User. A more flexible
>> configuration would be to create a special group, say fat,
>> and add all users that need to access the disk to this
>> group, and then configure the fstab entry with
>> uid=root,gid=fat.
>>
>> João Luis.
>>
>
> I understood enough of what you wrote to suspect source of
> (likely) unrelated problem I've had.
>
> I've a collection of USB flash drives which, when plugged
> into a running Debian 6.0.5 system, do not mount in an
> apparently uniform manner.
>
> The various drives may have been formatted:
> 1. by WinXP Pro SP3 as FAT16, FAT32, or NTFS
> 2. by gparted under Debian 6.0.5 as ext???, FAT16, FAT32, or
> NTFS
> 3. by the stand alone Live version of gparted as in #2
>
> I don't have any current examples so I can not ask an
> answerable specific question.
Note that ext2, 3 and 4 don't support umask, uid and gid mount options, so
even user mounts (or mounts via dbus) cannot overwrite the filesystem
permissions. Note that sometimes a file or directory is created in a
removable device within an ext{2,3,4} filesystem under some user joe in
one computer and people expects that joe can access this file or directory
in every computer, but this may not happen, as joe can have different user
ids in different computers. Filesystems store the user id, not the
username.
If you want an ext{2,3,4} filesystem to accessible by everyone in every
computer, there is a workaround: change its root permissions to those of
the tmp directory. To do so, as root, mount the filesystem in some
directory (say /mnt), do the command
chmod 1777 /mnt/
and umount /mnt.
> Could someone point me to a broad intermediate level survey
> of permissions (issues and implications) in order that when
> (not if) I run into a problem I'll be able to ask an
> intelligent question? TIA
I could not point to an specific text right now, but there are a lot of
good ones freely available in the internet. Maybe someone can help here?
João Luis.
Here's a resonably good one.
Larry
http://www.dartmouth.edu/~rc/help/faq/permissions.html
--
To UNSUBSCRIBE, email to debian-user-REQUEST@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org
Archive: [🔎] 726a18a6286e0561709d8762368b8463.squirrel@nonada.if.usp.br">[🔎] 726a18a6286e0561709d8762368b8463.squirrel@nonada.if.usp.br">http://lists.debian.org/[🔎] 726a18a6286e0561709d8762368b8463.squirrel@nonada.if.usp.br
Reply to: