UMSDOS HOWTO

3. Umsdos as your root partition

3.1 The pseudo-root concept.

With Umsdos, Linux can be installed in a standard DOS partition. Linux is then installed as a second (or third) OS in the partition. To avoid name collision (there is maybe a bin or tmp directory in the drive C: already), Umsdos use a smart trick: The pseudo-root.

All Linux files are installed in a DOS subdirectory called linux, generally C: LINUX. The normal Linux/Unix directory structure goes there. So you get

• C:\LINUX\BIN
  

• C:\LINUX\ETC
  

• C:\LINUX\LIB
  

• C:\LINUX\ROOT
  

• C:\LINUX\SBIN
  

• C:\LINUX\TMP
  

• C:\LINUX\USR
  

• C:\LINUX\VAR
  

When the Umsdos boot, it probes for the directory linux and then /linux/etc. If it exist, it activates the pseudo-root mode.

Mostly, the pseudo-root mode switch the root of the partition to C:\\LINUX giving the conventional Unix directory layout

• /bin
  

• /etc
  

• /lib
  

• /root
  

• /sbin
  

• /tmp
  

• /usr
  

• /var
  

To this list, it adds a new one called DOS. This one is a virtual directory.

3.2 Things to know about the pseudo-root

• This mode can only be triggered at boot time. There is no way to activate this by a mount command.
• This mechanism is purely a different view of a normal Umsdos file-system. This means that a partition normally used as a root partition can be normally mounted. There won't be any pseudo-root effect. For example, if you boot linux with a maintenance floppy and mount your normal root partition in /mnt, you will find all your linux directory in /mnt/linux/bin, /mnt/linux/etc and so on.