Both Ms-DOS and OS/2 are single-user operating systems. Their respective filesystems lack most of the features expected in a multi-user operating system like Linux.
For one, there is no file ownership. This means that when a DOS hard drive is mounted into the Linux filesystem tree, files will be available to every user on the machine.
Keep in mind that Linux is a multi-user system. It is fairly easy to create user accounts on your system for co-workers so they can share your CPU or system resources. It would be unpleasant to find out later that everyone has access to every personal file you have in your DOS partitions.
Linux offers a neat solution to this. You can logically apply an ownership and permission flag to all files and directories on DOS partitions. No special data is written to the partitions. It is simply a presentation mode used by Linux.
Here are the options you can control
Text files are stored in a slightly different format on Ms-DOS and OS/2, compared to UNIX and Linux. The difference lies in the way end-of-file is identified.
Ms-DOS uses a sequence of two characters, an
Carriage-return followed by an ASCII
UNIX use only a single
Hpfs file-systems share
one option to make life easier when sharing files on a hard
drive between Linux and Ms-DOS or OS/2.
Here are the modes available:
Once a translation mode is selected, it is done both at read and write times. This makes it nearly transparent to Linux applications.
Please note that the current trend is towards flexible utilities (editors) which can handle both formats instead of using a filesystem trick like this one.