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Very short explanation for the impatient!!!

Umsdos is a file system driver that run on top the MSDOS fs driver.

It is written by Jacques Gelinas (jacques@solucorp.qc.ca)

Umsdos is not a file system per se, but a twist to make a boring

one into a useful one.

It gives you:

        long file name

        Permissions and owner

        Links

        Special files (devices, pipe...)

        All is need to be a linux root fs.

There is plenty of documentation on it in the source. A formated document

made from those comments is available from

sunsite.unc.edu:/pub/Linux/system/Filesystems/umsdos.

Mostly...

You mount a DOS partition like this

mount -t umsdos /dev/hda3 /mnt

         ^

---------|

All option are passed to the msdos drivers. Option like uid,gid etc are

given to msdos.

The default behavior of Umsdos is to do the same thing as the msdos driver

mostly passing commands to it without much processing. Again, this is

the default. After doing the mount on a DOS partition, nothing special

happen. This is why all mount options are passed to the Msdos fs driver.

Umsdos use a special DOS file --linux-.--- to store the information

which can't be handle by the normal MsDOS file system. This is the trick.

--linux-.--- is optional. There is one per directory.

**** If --linux-.--- is missing, then Umsdos process the directory the

     same way the msdos driver do. Short file name, no goodies, default

     owner and permissions. So each directory may have or not this

     --linux-.---

Now, how to get those --linux-.---.

\begin joke_section

        Well send me a directory content

        and I will send you one customised for you.

        $5 per directory. Add any applicable taxes.

\end joke_section

A utility umssync creates those. The kernel maintain them. It is available

from the same directory above (sunsite) in the file umsdos_progs-0.7.tar.gz.

A compiled version is available in umsdos_progs-0.7.bin.tar.gz.

So in our example, after mounting mnt, we do

umssync .

This will promote this directory (a recursive option is available) to full

umsdos capabilities (long name ...). A ls -l before and after won't show

much difference however. The file which were there are still there. But now

you can do all this:

        chmod 644 *

        chown you.your_groupe *

        ls >THIS_IS.A.VERY.LONG.NAME

        ln -s toto tata

        ls -l

Once a directory is promoted, all subdirectory created will inherit that

promotion.

What happen if you boot DOS and create files in those promoted directories ?

Umsdos won't notice new files, but will signal removed file (it won't crash).

Using umssync in /etc/rc will make sure the DOS directory is in sync with

the --linux-.---.

It is a good idea to put the following command in your RC file just

after the "mount -a":

        mount -a

        /sbin/umssync -i+ -c+ -r99 /umsdos_mount_point

        (You put one for each umsdos mount point in the fstab)

This will insure nice operation. A umsdos.fsck is in the making,

so you will be allowed to managed umsdos partition in the same way

other filesystem are, using the generic fsck front end.

Hope this helps!