<s>
Linux	B-Application
has	O
several	O
filesystem	B-Application
drivers	O
for	O
the	O
File	B-Application
Allocation	I-Application
Table	I-Application
(	O
FAT	O
)	O
filesystem	B-Application
format	O
.	O
</s>
<s>
These	O
are	O
commonly	O
known	O
by	O
the	O
names	O
used	O
in	O
the	O
mount	B-Device
command	O
to	O
invoke	O
particular	O
drivers	O
in	O
the	O
kernel	O
:	O
,	O
,	O
and	O
.	O
</s>
<s>
Most	O
of	O
the	O
major	O
Linux	B-Application
distributions	O
,	O
including	O
RedHat	O
,	O
SuSE	O
,	O
and	O
Debian	O
,	O
do	O
not	O
employ	O
to	O
permit	O
installation	O
of	O
Linux	B-Application
on	O
a	O
FAT	O
disc	O
volume	O
.	O
</s>
<s>
These	O
include	O
distributions	O
such	O
as	O
Phat	O
Linux	B-Application
,	O
which	O
installs	O
in	O
C:\PHAT	O
on	O
DOS	B-Device
by	O
unpacking	O
a	O
ZIP	B-General_Concept
file	I-General_Concept
and	O
is	O
booted	O
by	O
running	O
a	O
COMMAND.COM	B-Operating_System
script	O
named	O
LINUX.BAT	O
,	O
and	O
ZipSlack	O
.	O
</s>
<s>
UMSDOS	O
was	O
removed	O
from	O
the	O
Linux	B-Application
2.6.11	O
kernel	O
for	O
lack	O
of	O
maintenance	O
.	O
</s>
<s>
Earlier	O
Linux	B-Application
distributions	O
which	O
used	O
UMSDOS	O
are	O
MuLinux	O
,	O
Monkey	O
Linux	B-Application
and	O
Winlinux	O
2000	O
.	O
</s>
<s>
All	O
of	O
the	O
Linux	B-Application
filesystem	B-Application
drivers	O
support	O
all	O
three	O
FAT	O
types	O
,	O
namely	O
FAT12	B-Application
,	O
FAT16	B-Application
and	O
FAT32	B-Application
.	O
</s>
<s>
Where	O
they	O
differ	O
is	O
in	O
the	O
provision	O
of	O
support	O
for	O
long	O
filenames	O
,	O
beyond	O
the	O
8.3	O
filename	O
structure	O
of	O
the	O
original	O
FAT	B-Application
filesystem	I-Application
format	O
,	O
and	O
in	O
the	O
provision	O
of	O
Unix	O
file	O
semantics	O
that	O
do	O
not	O
exist	O
as	O
standard	O
in	O
the	O
FAT	B-Application
filesystem	I-Application
format	O
such	O
as	O
file	O
permissions	O
.	O
</s>
<s>
The	O
filesystem	B-Application
drivers	O
are	O
mutually	O
exclusive	O
.	O
</s>
<s>
Only	O
one	O
can	O
be	O
used	O
to	O
mount	B-Device
any	O
given	O
disk	O
volume	O
at	O
any	O
given	O
time	O
.	O
</s>
<s>
The	O
filesystem	B-Application
driver	O
provides	O
no	O
extra	O
Unix	O
file	O
semantics	O
and	O
no	O
long	O
filename	O
support	O
.	O
</s>
<s>
If	O
a	O
FAT	O
disk	O
filesystem	B-Application
is	O
mounted	O
using	O
this	O
driver	O
,	O
only	O
8.3	O
filenames	O
will	O
be	O
visible	O
,	O
no	O
long	O
filenames	O
will	O
be	O
accessible	O
,	O
nor	O
will	O
any	O
long	O
filename	O
data	O
structures	O
of	O
any	O
kind	O
on	O
the	O
disk	O
volume	O
be	O
maintained	O
.	O
</s>
<s>
The	O
filesystem	B-Application
driver	O
provides	O
long	O
filename	O
support	O
using	O
the	O
same	O
disk	O
data	O
structures	O
that	O
Microsoft	B-Application
Windows	I-Application
uses	O
for	O
VFAT	B-Application
long	O
filename	O
support	O
on	O
FAT	B-Application
format	I-Application
volumes	O
,	O
but	O
it	O
does	O
not	O
support	O
any	O
extra	O
Unix	O
file	O
semantics	O
.	O
</s>
<s>
The	O
filesystem	B-Application
driver	O
provides	O
long	O
filename	O
support	O
,	O
and	O
extra	O
Unix	O
file	O
semantics	O
.	O
</s>
<s>
However	O
,	O
it	O
does	O
so	O
using	O
on-disk	O
data	O
structures	O
that	O
are	O
not	O
recognized	O
by	O
any	O
filesystem	B-Application
drivers	O
for	O
any	O
operating	O
systems	O
other	O
than	O
Linux	B-Application
.	O
</s>
<s>
Therefore	O
,	O
it	O
can	O
be	O
used	O
in	O
situations	O
where	O
it	O
is	O
desirable	O
to	O
install	O
Linux	B-Application
on	O
and	O
run	O
it	O
from	O
a	O
FAT	O
disk	O
volume	O
,	O
which	O
require	O
such	O
semantics	O
to	O
be	O
available	O
.	O
</s>
<s>
However	O
,	O
Linux	B-Application
installed	O
on	O
and	O
running	O
from	O
such	O
a	O
disk	O
volume	O
is	O
slower	O
than	O
Linux	B-Application
installed	O
on	O
and	O
running	O
from	O
a	O
disk	O
volume	O
formatted	O
with	O
,	O
for	O
example	O
,	O
the	O
ext2	B-Application
filesystem	B-Application
format	O
.	O
</s>
<s>
Further	O
,	O
unless	O
a	O
utility	O
program	O
is	O
regularly	O
run	O
every	O
time	O
that	O
one	O
switches	O
from	O
running	O
Windows	O
to	O
running	O
Linux	B-Application
,	O
certain	O
changes	O
made	O
to	O
files	O
and	O
directories	O
on	O
the	O
disk	O
by	O
Windows	O
will	O
cause	O
error	O
messages	O
about	O
inaccessible	O
files	O
in	O
Linux	B-Application
.	O
</s>
<s>
,	O
although	O
lacking	O
full	O
Unix	O
file	O
semantics	O
and	O
lacking	O
the	O
ability	O
to	O
have	O
Linux	B-Application
installed	O
on	O
and	O
running	O
from	O
a	O
FAT	O
disk	O
volume	O
,	O
does	O
not	O
have	O
the	O
aforementioned	O
disadvantages	O
of	O
when	O
it	O
comes	O
to	O
simply	O
sharing	O
data	O
on	O
a	O
FAT	O
disk	O
volume	O
between	O
Linux	B-Application
and	O
other	O
operating	O
systems	O
such	O
as	O
Windows	O
.	O
</s>
<s>
Its	O
data	O
structures	O
are	O
the	O
same	O
as	O
those	O
used	O
by	O
Windows	O
for	O
VFAT	B-Application
long	O
filenames	O
,	O
and	O
it	O
does	O
not	O
require	O
running	O
a	O
synchronization	O
utility	O
in	O
order	O
to	O
prevent	O
Windows	O
and	O
Linux	B-Application
data	O
structures	O
from	O
becoming	O
disjointed	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
it	O
is	O
the	O
most	O
appropriate	O
of	O
Linux	B-Application
's	O
FAT	B-Application
filesystem	I-Application
drivers	O
to	O
use	O
in	O
the	O
majority	O
of	O
situations	O
.	O
</s>
<s>
As	O
mentioned	O
previously	O
,	O
all	O
of	O
the	O
Linux	B-Application
filesystem	B-Application
drivers	O
support	O
all	O
of	O
the	O
three	O
File	B-Application
Allocation	I-Application
Table	I-Application
sizes	O
,	O
12-bit	O
,	O
16-bit	O
,	O
and	O
32-bit	O
.	O
</s>
<s>
Other	O
common	O
features	O
that	O
they	O
all	O
support	O
are	O
various	O
Linux	B-Application
mounting	O
options	O
(	O
specified	O
with	O
the	O
-o	O
option	O
to	O
the	O
mount	B-Device
command	O
)	O
:	O
</s>
<s>
uid	O
and	O
gidThese	O
two	O
options	O
tell	O
the	O
filesystem	B-Application
driver	O
to	O
set	O
the	O
(	O
default	O
,	O
in	O
the	O
case	O
of	O
)	O
owner	O
user	O
ID	O
and	O
group	O
ID	O
to	O
be	O
a	O
single	O
,	O
specified	O
,	O
value	O
for	O
all	O
files	O
in	O
the	O
volume	O
.	O
</s>
<s>
So	O
,	O
for	O
example	O
,	O
to	O
specify	O
to	O
the	O
filesystem	B-Application
driver	O
that	O
all	O
files	O
and	O
directories	O
are	O
to	O
have	O
owner	O
ID	O
745	O
and	O
group	O
ID	O
15	O
,	O
the	O
mount	B-Device
command	O
would	O
be	O
invoked	O
as	O
.	O
</s>
<s>
Linux	B-Application
filesystem	B-Application
drivers	O
do	O
not	O
at	O
present	O
incorporate	O
support	O
for	O
file/directory	O
passwords	O
on	O
FAT12/FAT16/FAT32	O
volumes	O
and	O
multi-user	O
world/group/owner	O
access	O
permissions	O
for	O
read/write/delete/execute	O
rights	O
on	O
FAT12/FAT16	O
volumes	O
as	O
implemented	O
in	O
various	O
operating	O
systems	O
of	O
the	O
Digital	O
Research	O
family	O
,	O
including	O
DR-DOS	B-Application
,	O
PalmDOS	B-Operating_System
,	O
Novell	B-Operating_System
DOS	I-Operating_System
,	O
OpenDOS	B-Application
,	O
FlexOS	B-Operating_System
,	O
Concurrent	B-Operating_System
DOS	I-Operating_System
,	O
Multiuser	B-Operating_System
DOS	I-Operating_System
,	O
System	O
Manager	O
and	O
REAL/32	B-Operating_System
.	O
</s>
<s>
For	O
example	O
,	O
to	O
specify	O
to	O
the	O
filesystem	B-Application
driver	O
that	O
no	O
"	O
group	O
"	O
or	O
"	O
other	O
"	O
access	O
is	O
to	O
be	O
allowed	O
,	O
the	O
mount	B-Device
command	O
would	O
be	O
invoked	O
as	O
.	O
</s>
<s>
It	O
is	O
possible	O
for	O
the	O
filesystem	B-Application
drivers	O
to	O
convert	O
the	O
newline	O
conventions	O
in	O
files	O
,	O
between	O
LF	O
termination	O
and	O
CRLF	O
termination	O
,	O
on	O
the	O
fly	O
as	O
files	O
are	O
read	O
and	O
written	O
.	O
</s>
<s>
The	O
filesystem	B-Application
drivers	O
can	O
perform	O
conversion	O
for	O
some	O
files	O
,	O
attempting	O
to	O
auto-detect	O
what	O
files	O
to	O
convert	O
based	O
upon	O
the	O
extension	O
portion	O
of	O
the	O
filename	O
,	O
or	O
globally	O
for	O
all	O
files	O
.	O
</s>
<s>
The	O
FAT	B-Application
filesystem	I-Application
driver	O
stores	O
all	O
of	O
the	O
extra	O
information	O
relating	O
to	O
Unix	O
file	O
semantics	O
in	O
what	O
,	O
to	O
another	O
FAT	B-Application
filesystem	I-Application
driver	O
,	O
appears	O
to	O
be	O
just	O
a	O
normal	O
file	O
in	O
each	O
directory	O
and	O
subdirectory	O
,	O
named	O
--LINUX-.---	O
.	O
</s>
<s>
In	O
the	O
absence	O
of	O
this	O
file	O
in	O
any	O
given	O
directory	O
,	O
and	O
thus	O
by	O
default	O
,	O
the	O
filesystem	B-Application
driver	O
provides	O
the	O
same	O
semantics	O
as	O
the	O
filesystem	B-Application
driver	O
does	O
for	O
the	O
directory	O
:	O
only	O
8.3	O
filenames	O
and	O
no	O
extra	O
Unix	O
file	O
semantics	O
.	O
</s>
<s>
This	O
is	O
the	O
utility	O
program	O
that	O
is	O
run	O
,	O
across	O
every	O
directory	O
on	O
the	O
disc	O
volume	O
,	O
every	O
time	O
that	O
one	O
switches	O
from	O
running	O
Windows	O
to	O
running	O
Linux	B-Application
,	O
in	O
order	O
for	O
the	O
filesystem	B-Application
driver	O
to	O
incorporate	O
any	O
changes	O
made	O
to	O
files	O
and	O
directories	O
by	O
Windows	O
into	O
its	O
private	O
data	O
structures	O
in	O
its	O
--LINUX-.---	O
file	O
.	O
</s>
<s>
By	O
default	O
,	O
the	O
umssync	O
tool	O
creates	O
--LINUX-.---	O
files	O
in	O
directories	O
if	O
they	O
do	O
not	O
already	O
exist	O
,	O
resulting	O
in	O
such	O
a	O
file	O
in	O
every	O
directory	O
in	O
the	O
disc	O
volume	O
.	O
</s>
<s>
When	O
switching	O
between	O
Windows	O
and	O
Linux	B-Application
this	O
behaviour	O
is	O
not	O
often	O
considered	O
desirable	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
normal	O
mode	O
of	O
operation	O
when	O
invoking	O
umssync	O
after	O
switching	O
from	O
Windows	O
to	O
Linux	B-Application
(	O
which	O
is	O
usually	O
done	O
by	O
running	O
the	O
tool	O
at	O
Linux	B-Application
boot	O
time	O
from	O
a	O
startup	O
script	O
)	O
is	O
to	O
employ	O
the	O
-c	O
option	O
to	O
the	O
command	O
,	O
which	O
prevents	O
the	O
creation	O
of	O
any	O
new	O
--LINUX-.---	O
files	O
in	O
directories	O
that	O
do	O
not	O
already	O
possess	O
them	O
.	O
</s>
<s>
As	O
mentioned	O
,	O
permits	O
installing	O
Linux	B-Application
on	O
,	O
and	O
then	O
bootstrapping	O
and	O
running	O
it	O
from	O
,	O
a	O
FAT	B-Application
format	I-Application
disc	O
volume	O
.	O
</s>
<s>
The	O
advantage	O
of	O
this	O
is	O
that	O
it	O
permits	O
the	O
use	O
of	O
Linux	B-Application
on	O
a	O
computer	O
where	O
DOS	B-Device
is	O
already	O
installed	O
,	O
without	O
requiring	O
that	O
the	O
hard	O
disc	O
be	O
repartitioned	B-Application
.	O
</s>
<s>
Linux	B-Application
is	O
not	O
bootstrapped	O
directly	O
from	O
a	O
Volume	B-Device
Boot	I-Device
Record	I-Device
in	O
such	O
a	O
scenario	O
.	O
</s>
<s>
Instead	O
DOS	B-Device
is	O
first	O
bootstrapped	O
,	O
and	O
loadlin	B-Application
or	O
is	O
used	O
to	O
then	O
bootstrap	O
Linux	B-Application
from	O
DOS	B-Device
.	O
</s>
<s>
The	O
convention	O
for	O
such	O
an	O
installation	O
is	O
for	O
the	O
Linux	B-Application
root	B-Application
directory	I-Application
to	O
be	O
a	O
subdirectory	O
of	O
the	O
root	B-Application
directory	I-Application
of	O
the	O
DOS	B-Device
boot	B-Application
volume	I-Application
,	O
e.g.	O
</s>
<s>
C:\LINUX	O
.	O
</s>
<s>
The	O
various	O
Linux	B-Application
top-level	O
directories	O
are	O
thus	O
,	O
to	O
DOS	B-Device
,	O
directories	O
such	O
as	O
C:\LINUX\ETC	O
(	O
for	O
/etc	O
)	O
,	O
C:\LINUX\BIN	O
(	O
for	O
/bin	O
)	O
,	O
C:\LINUX\LIB	O
(	O
for	O
/lib	O
)	O
,	O
and	O
so	O
forth	O
.	O
</s>
<s>
The	O
filesystem	B-Application
driver	O
automatically	O
prepends	O
the	O
C:\LINUX\	O
to	O
all	O
pathnames	O
.	O
</s>
<s>
The	O
location	O
of	O
the	O
Linux	B-Application
root	B-Application
directory	I-Application
is	O
supplied	O
to	O
the	O
filesystem	B-Application
driver	O
in	O
the	O
first	O
place	O
via	O
an	O
option	O
to	O
the	O
loadlin	B-Application
command	O
.	O
</s>
<s>
So	O
,	O
for	O
example	O
,	O
loadlin	B-Application
would	O
be	O
invoked	O
with	O
a	O
command	O
line	O
such	O
as	O
.	O
</s>
<s>
The	O
installation	O
of	O
Linux	B-Application
into	O
such	O
a	O
directory	O
in	O
the	O
first	O
place	O
simply	O
involves	O
unpacking	O
files	O
from	O
an	O
archive	O
into	O
that	O
directory	O
and	O
its	O
subdirectories	O
.	O
</s>
<s>
Such	O
an	O
installation	O
also	O
generally	O
requires	O
the	O
use	O
of	O
a	O
swap	O
file	O
rather	O
than	O
a	O
swap	O
partition	B-Application
for	O
Linux	B-Application
,	O
however	O
this	O
is	O
related	O
to	O
the	O
desire	O
not	O
to	O
repartition	O
the	O
hard	O
disc	O
and	O
unrelated	O
to	O
the	O
filesystem	B-Application
driver	O
per	O
se	O
.	O
</s>
<s>
Although	O
the	O
filesystem	B-Application
drivers	O
in	O
the	O
kernel	O
make	O
it	O
possible	O
to	O
access	O
files	O
and	O
directories	O
on	O
FAT	O
formatted	O
volumes	O
in	O
the	O
normal	O
manner	O
,	O
it	O
is	O
also	O
possible	O
to	O
do	O
so	O
without	O
kernel	O
driver	O
support	O
,	O
using	O
the	O
utility	O
programs	O
that	O
form	O
the	O
mtools	B-Application
utility	O
suite	O
.	O
</s>
<s>
Like	O
the	O
FAT	B-Application
filesystem	I-Application
driver	O
,	O
provides	O
long	O
filename	O
support	O
using	O
the	O
same	O
disc	O
data	O
structures	O
that	O
Microsoft	B-Application
Windows	I-Application
uses	O
.	O
</s>
<s>
Alternately	O
,	O
one	O
of	O
the	O
FUSE	B-Application
filesystem	B-Application
drivers	O
may	O
be	O
used	O
—	O
FatFuse	O
,	O
FuseFat	O
or	O
.	O
</s>
<s>
A	O
modern	O
equivalent	O
of	O
UMSDOS	O
is	O
POSIX	O
Overlay	O
Filesystem	B-Application
(	O
)	O
.	O
</s>
<s>
It	O
works	O
in	O
FUSE	B-Application
.	O
</s>
