[ubuntu-uk] USB Hard Drive Group Permissions

[Stuart Bird]

Andrew

Thank you for such an in depth and informative response. Changing the  uid= to blank did the trick in the end.

Stu 

----- Original Message ----
From: Andrew Oakley <andrew at aoakley.com>
To: British Ubuntu Talk <ubuntu-uk at lists.ubuntu.com>
Sent: Friday, 8 February, 2008 11:25:18 AM
Subject: Re: [ubuntu-uk] USB Hard Drive Group Permissions

Stuart 
Bird 
wrote:
> 
The 
first 
way 
is 
to 
use: 
gksudo 
nautilus 
to 
access 
and 
edit 
files 
as 
> 
root. 
The 
second 
way 
is 
to 
add 
myself 
to 
the 
root 
group 
which 
then 
> 
allows 
me 
full 
control 
from 
my 
normal 
users 
account.
> 
> 
Can 
anyone 
advise 
if 
these 
are 
viable 
(ie 
safe) 
long 
term 
solutions 
or 
> 
should 
I 
keep 
searching 
for 
a 
better 
way.

Are 
you 
logged 
into 
Gnome 
when 
you 
attach 
the 
external 
drive, 
or 
do 
you 
have 
it 
plugged 
in 
when 
you 
switch 
on?

If 
you 
have 
it 
plugged 
in 
when 
you 
switch 
on, 
it 
won't 
know 
who 
to 
mount 
it 
as, 
and 
may 
default 
to 
root; 
you 
may 
need 
to 
write 
an 
/etc/fstab 
rule 
for 
the 
external 
drive 
with 
uid=youruserid 
and/or 
gid=yourgroup 
. 
For 
example, 
my 
username 
is 
aoakley, 
so 
to 
mount 
a 
FAT 
external 
drive 
at 
boot 
time, 
I 
might 
write 
an 
/etc/fstab 
rule 
like:

/dev/sdb 
/media/mymountpoint 
vfat 
rw,uid=aoakley 
0 
0

Beware 
that 
not 
all 
external 
hard 
drives 
are 
VFAT! 
Some 
may 
be 
NTFS 
or 
somesuch.

Alternatively 
I 
might 
use 
umask 
to 
make 
it 
read/writable 
to 
everyone 
within 
a 
particular 
group:

/dev/sdb 
/media/mymountpoint 
vfat 
rw,umask=007 
0 
0

...which 
would 
make 
it 
read/writable 
to 
everyone 
in 
the 
root 
group, 
or:

/dev/sdb 
/media/mymountpoint 
vfat 
rw,gid=aoakley,umask=007 
0 
0

...which 
would 
make 
it 
read/writable 
to 
everyone 
in 
aoakley's 
group, 
or:

/dev/sdb 
/media/mymountpoint 
vfat 
rw,umask=000 
0 
0

...which 
would 
make 
it 
owned 
by 
root 
but 
read/writable 
to 
everyone, 
even 
guest 
users 
(INSECURE!).

(Stop 
reading 
now 
if 
you 
attach 
the 
drive 
before 
the 
machine 
is 
switched 
on, 
or 
if 
you 
always 
leave 
the 
drive 
plugged 
in. 
The 
following 
only 
apply 
if 
you 
attach 
the 
drive 
AFTER 
you 
log 
in 
to 
Gnome.)

Newly 
plugged-in 
USB 
drives 
AFTER 
you 
have 
logged 
in 
to 
Gnome 
should 
automatically 
be 
mounted 
as 
the 
logged-in 
user 
(eg. 
aoakley 
for 
myself) 
and 
root 
as 
the 
group.

Have 
you 
got 
more 
than 
one 
user 
logged 
into 
Gnome 
perhaps? 
This 
might 
cause 
confusion.

For 
example, 
I 
log 
in 
to 
Gnome 
and 
insert 
a 
1GB 
USB 
key, 
so 
I 
get:

$ 
cat 
/etc/mtab
...
/dev/sdb 
/media/AO\0401GB 
vfat 
rw,nosuid,nodev,shortname=mixed,uid=1000,utf8,umask=077,usefree 
0 
0
$ 
ls 
-l 
/media
total 
28
drwx------ 
10 
aoakley 
root 
16384 
1970-01-01 
01:00 
AO 
1GB
...

The 
last 
line 
shows 
that 
the 
user 
is 
aoakley 
(my 
local 
logged-in 
user) 
and 
the 
group 
is 
root.

If 
you 
aren't 
getting 
this, 
then 
either 
you're 
not 
using 
Gnome 
Automount, 
or 
something 
is 
wrong 
with 
Gnome 
Automount. 
Have 
you 
written 
an 
/etc/fstab 
entry 
which 
is 
overruling 
Gnome 
Automount? 
If 
so, 
try 
commenting 
it 
out.

Is 
automount 
running? 
Check 
for 
gnome-v* 
processes, 
you 
should 
see 
two; 
gnome-volume-manager 
and 
gnome-vfs-daemon 
. 
If 
not, 
something 
is 
wrong 
with 
your 
gnome 
start-up 
sequence 
(too 
complex 
to 
discuss 
here).

$ 
sudo 
ps 
-e 
| 
grep 
gnome-v
5600 
?  
  
  
  
00:00:00 
gnome-volume-ma
5630 
?  
  
  
  
00:00:00 
gnome-vfs-daemo

Check 
your 
Gnome 
Automount 
preferences 
in 
System 
- 
Preferences 
- 
Removable 
Drives 
And 
Media 
- 
Removable 
Storage 
- 
Mount 
Removable 
Drives 
When 
Hot 
Plugged 
TICKED 
- 
Mount 
Removable 
Media 
When 
Inserted 
TICKED.

Check 
your 
Gnome 
Automount 
configuration 
in 
(Alt-F2) 
- 
gconf-editor 
- 
System 
- 
Storage 
. 
Check 
that 
there 
is 
NOT 
some 
special 
rule 
for 
your 
hard 
drive. 
Then 
check 
under 
Default 
Options 
- 
(Your 
storage 
type) 
and 
make 
sure 
that 
the 
uid= 
config 
is 
either 
not 
present, 
or 
blank.

For 
instance, 
my 
gconf-editor 
- 
System 
- 
Storage 
- 
Default 
Options 
- 
VFat 
- 
mount_options 
shows:

[shortname=mixed,uid=,utf8,umask=077,exec,usefree]

The 
important 
bit 
there 
is 
"uid=" 
(uid 
equals 
empty) 
which 
defaults 
to 
the 
currently 
logged-in 
user 
in 
Gnome.

-- 
Andrew 
Oakley


-- 
ubuntu-uk at lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk
https://wiki.kubuntu.org/UKTeam/






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