Various utilities exist to interface with the world of MS-DOS. The most well-known application is the Linux MS-DOS Emulator, which allows you to run many MS-DOS applications directly from Linux. Although Linux and MS-DOS are completely different operating systems, the 80386 protected-mode environment allows certain tasks to behave as if they were running in 8086-emulation mode, as MS-DOS applications do.
The MS-DOS emulator is still under development, yet many popular applications run under it. Understandably, however, MS-DOS applications which use bizarre or esoteric features of the system may never be supported, because it is only an emulator. For example, you wouldn't expect to be able to run any programs which use 80386 protected-mode features, such as Microsoft Windows (in 386 enhanced mode, that is).
Applications which run successfully under the Linux MS-DOS Emulator include 4DOS (a command interpreter), Foxpro 2.0, Harvard Graphics, MathCad, Stacker 3.1, Turbo Assembler, Turbo C/C++, Turbo Pascal, Microsoft Windows 3.0 (in real mode), and WordPerfect 5.1. Standard MS-DOS commands and utilities (such as PKZIP, and so on) work with the emulator as well.
The MS-DOS Emulator is meant mostly as an ad hoc solution for those people who need MS-DOS only for a few applications, but use Linux for everything else. It's not meant to be a complete implementation of MS-DOS. Of course, if the Emulator doesn't satisfy your needs, you can always run MS-DOS as well as Linux on the same system. Using the LILO boot loader, you can specify at boot time which operating system to start. Linux can coexist with other operating systems, such as OS/2, as well.
Linux provides a seamless interface for transferring files between Linux and MS-DOS. You can mount an MS-DOS partition or floppy under Linux, and directly access MS-DOS files as you would any other.
Currently under development is a project known as WINE---a Microsoft Windows emulator for the X Window System under Linux. Once WINE is complete, users will be able to run MS-Windows applications directly from Linux. This is similar to the proprietary WABI Windows emulator from Sun Microsystems. At the time of this writing, WINE is still in the early stages of development, but the outlook is good.
In Chapter 5 we'll talk about the MS-DOS tools available for Linux.