Mtools is a collection of tools to allow Unix systems to manipulate MS-
DOS files: read, write, and move around files on an MS-DOS filesystem
(typically a floppy disk). Where reasonable, each program attempts to
emulate the MS-DOS equivalent command. However, unnecessary restric-
tions and oddities of DOS are not emulated. For instance, it is possi-
ble to move subdirectories from one subdirectory to another.
Mtools is sufficient to give access to MS-DOS filesystems. For
instance, commands such as mdir a: work on the a: floppy without any
preliminary mounting or initialization (assuming the default
`/etc/mtools.conf' works on your machine). With mtools, one can change
floppies too without unmounting and mounting.
Where to get mtools
Mtools can be found at the following places (and their mirrors):
Before reporting a bug, make sure that it has not yet been fixed in the
Alpha patches which can be found at:
These patches are named mtools-version-ddmm.taz, where version stands
for the base version, dd for the day and mm for the month. Due to a
lack of space, I usually leave only the most recent patch.
There is an mtools mailing list at mtools @ tux.org . Please send all
bug reports to this list. You may subscribe to the list by sending a
message with 'subscribe mtools @ tux.org' in its body to majordomo @
tux.org . (N.B. Please remove the spaces around the "@" both times. I
left them there in order to fool spambots.) Announcements of new
mtools versions will also be sent to the list, in addition to the linux
announce newsgroups. The mailing list is archived at
Common features of all mtools commands
Options and filenames
MS-DOS filenames are composed of a drive letter followed by a colon, a
subdirectory, and a filename. Only the filename part is mandatory, the
drive letter and the subdirectory are optional. Filenames without a
expect in MS-DOS.
Most mtools commands allow multiple filename parameters, which doesn't
follow MS-DOS conventions, but which is more user-friendly.
Most mtools commands allow options that instruct them how to handle
file name clashes. See section name clashes, for more details on these.
All commands accept the -V flags which prints the version, and most
accept the -v flag, which switches on verbose mode. In verbose mode,
these commands print out the name of the MS-DOS files upon which they
act, unless stated otherwise. See section Commands, for a description
of the options which are specific to each command.
The meaning of the drive letters depends on the target architectures.
However, on most target architectures, drive A is the first floppy
drive, drive B is the second floppy drive (if available), drive J is a
Jaz drive (if available), and drive Z is a Zip drive (if available).
On those systems where the device name is derived from the SCSI id, the
Jaz drive is assumed to be at Scsi target 4, and the Zip at Scsi target
5 (factory default settings). On Linux, both drives are assumed to be
the second drive on the Scsi bus (/dev/sdb). The default settings can
be changes using a configuration file (see section Configuration).
The drive letter : (colon) has a special meaning. It is used to access
image files which are directly specified on the command line using the
mcopy -i my-image-file.bin ::file1 ::file2 .
This copies file1 and file2 from the image file (my-image-file.bin) to
the /tmp directory.
You can also supply an offset within the image file by including @@off-
set into the file name.
mcopy -i my-image-file.bin@@1M ::file1 ::file2 .
This looks for the image at the offset of 1M in the file, rather than
at its beginning.
Current working directory
The mcd command (`mcd') is used to establish the device and the current
working directory (relative to the MS-DOS filesystem), otherwise the
default is assumed to be A:/. However, unlike MS-DOS, there is only one
working directory for all drives, and not one per drive.
prn.txt PRN~1.TXT PRN is a device name
.abc ABC~1 null filename
hot+cold HOT_CO~1 illegal character
As you see, the following transformations happen to derive a short
* Illegal characters are replaced by underscores. The illegal
characters are ;+=',\"*\\<>/?:|.
* Extra dots, which cannot be interpreted as a main name/extension
separator are removed
* A ~n number is generated,
* The name is shortened so as to fit in the 8+3 limitation
The initial Unix-style file name (whether long or short) is also
called the primary name, and the derived short name is also called the
mcopy /etc/motd a:Reallylongname
Mtools creates a VFAT entry for Reallylongname, and uses REALLYLO as a
short name. Reallylongname is the primary name, and REALLYLO is the
mcopy /etc/motd a:motd
Motd fits into the DOS filename limits. Mtools doesn't need to
derivate another name. Motd is the primary name, and there is no sec-
In a nutshell: The primary name is the long name, if one exists, or
the short name if there is no long name.
Although VFAT is much more flexible than FAT, there are still names
that are not acceptable, even in VFAT. There are still some illegal
characters left (\"*\\<>/?:|), and device names are still reserved.
Unix name Long name Reason for the change
--------- ---------- ---------------------
prn prn-1 PRN is a device name
ab:c ab_c-1 illegal character
As you see, the following transformations happen if a long name is
Overwrites the existing file. It is not possible to overwrite a
directory with a file.
Renames the newly created file. Mtools prompts for the new file-
Renames the newly created file. Mtools chooses a name by itself,
skip Gives up on this file, and moves on to the next (if any)
To chose one of these actions, type its first letter at the prompt. If
you use a lower case letter, the action only applies for this file
only, if you use an upper case letter, the action applies to all files,
and you won't be prompted again.
You may also chose actions (for all files) on the command line, when
-D o Overwrites primary names by default.
-D O Overwrites secondary names by default.
-D r Renames primary name by default.
-D R Renames secondary name by default.
-D a Autorenames primary name by default.
-D A Autorenames secondary name by default.
-D s Skip primary name by default.
-D S Skip secondary name by default.
-D m Ask user what to do with primary name.
-D M Ask user what to do with secondary name.
Note that for command line switches lower/upper differentiates between
primary/secondary name whereas for interactive choices, lower/upper
differentiates between just-this-time/always.
The primary name is the name as displayed in Windows 95 or Windows NT:
i.e. the long name if it exists, and the short name otherwise. The
secondary name is the "hidden" name, i.e. the short name if a long name
By default, the user is prompted if the primary name clashes, and the
secondary name is autorenamed.
If a name clash occurs in a Unix directory, mtools only asks whether to
if all letters of the extension are the same case too. Mtools uses this
information when displaying the files, and also to generate the Unix
filename when mcopying to a Unix directory. This may have unexpected
results when applied to files written using an pre-7.0 version of DOS:
Indeed, the old style filenames map to all upper case. This is differ-
ent from the behavior of the old version of mtools which used to gener-
ate lower case Unix filenames.
high capacity formats
Mtools supports a number of formats which allow to store more data on
disk as usual. Due to different operating system abilities, these for-
mats are not supported on all OS'es. Mtools recognizes these formats
transparently where supported.
In order to format these disks, you need to use an operating system
specific tool. For Linux, suitable floppy tools can be found in the
fdutils package at the following locations~:
See the manpages included in that package for further detail: Use
superformat to format all formats except XDF, and use xdfcopy to format
The oldest method of fitting more data on a disk is to use more sectors
and more cylinders. Although the standard format uses 80 cylinders and
18 sectors (on a 3 1/2 high density disk), it is possible to use up to
83 cylinders (on most drives) and up to 21 sectors. This method allows
to store up to 1743K on a 3 1/2 HD disk. However, 21 sector disks are
twice as slow as the standard 18 sector disks because the sectors are
packed so close together that we need to interleave them. This problem
doesn't exist for 20 sector formats.
These formats are supported by numerous DOS shareware utilities such as
fdformat and vgacopy. In his infinite hubris, Bill Gate$ believed that
he invented this, and called it `DMF disks', or `Windows formatted
disks'. But in reality, it has already existed years before! Mtools
supports these formats on Linux, on SunOs and on the DELL Unix PC.
By using bigger sectors it is possible to go beyond the capacity which
can be obtained by the standard 512-byte sectors. This is because of
the sector header. The sector header has the same size, regardless of
how many data bytes are in the sector. Thus, we save some space by
using fewer, but bigger sectors. For example, 1 sector of 4K only takes
up header space once, whereas 8 sectors of 512 bytes have also 8 head-
ers, for the same amount of useful data.
This method allows to store up to 1992K on a 3 1/2 HD disk.
data than the others. Unfortunately, DOS can only handle disks where
each track contains the same amount of data. Thus 2m hides the fact
that the first track contains less data by using a shadow FAT. (Usu-
ally, DOS stores the FAT in two identical copies, for additional
safety. XDF stores only one copy, but tells DOS that it stores two.
Thus the space that would be taken up by the second FAT copy is saved.)
This also means that you should never use a 2m disk to store anything
else than a DOS fs.
Mtools supports these formats only on Linux.
XDF is a high capacity format used by OS/2. It can hold 1840 K per
disk. That's lower than the best 2m formats, but its main advantage is
that it is fast: 600 milliseconds per track. That's faster than the 21
sector format, and almost as fast as the standard 18 sector format. In
order to access these disks, make sure mtools has been compiled with
XDF support, and set the use_xdf variable for the drive in the configu-
ration file. See section Compiling mtools, and `misc variables', for
details on how to do this. Fast XDF access is only available for Linux
kernels which are more recent than 1.1.34.
Mtools supports this format only on Linux.
Caution / Attention distributors: If mtools is compiled on a Linux ker-
nel more recent than 1.3.34, it won't run on an older kernel. However,
if it has been compiled on an older kernel, it still runs on a newer
kernel, except that XDF access is slower. It is recommended that dis-
tribution authors only include mtools binaries compiled on kernels
older than 1.3.34 until 2.0 comes out. When 2.0 will be out, mtools
binaries compiled on newer kernels may (and should) be distributed.
Mtools binaries compiled on kernels older than 1.3.34 won't run on any
2.1 kernel or later.
All the Mtools commands return 0 on success, 1 on utter failure, or 2
on partial failure. All the Mtools commands perform a few sanity
checks before going ahead, to make sure that the disk is indeed an MS-
DOS disk (as opposed to, say an ext2 or minix disk). These checks may
reject partially corrupted disks, which might otherwise still be read-
able. To avoid these checks, set the MTOOLS_SKIP_CHECK environmental
variable or the corresponding configuration file variable (see section
An unfortunate side effect of not guessing the proper device (when mul-
tiple disk capacities are supported) is an occasional error message
from the device driver. These can be safely ignored.
The fat checking code chokes on 1.72 Mb disks mformatted with pre-2.0.7
mtools. Set the environmental variable MTOOLS_FAT_COMPATIBILITY (or the
corresponding configuration file variable, `global variables') to
bypass the fat checking.
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