Linux is a remarkably effective operating system, which in many cases can completely replace MS-DOS/Windows. However, there are always those of us who want to continue to use other operating systems as well as Linux. Enterprises considering Linux as an alternative desktop to Microsoft Windows often believe they have some essential Win32 applications or tools that prevent them from changing over. CIOs often eliminate the Linux option because someone advising them failed to mention that Linux can run Win32 applications.

Linux satisfies such yearnings with internal enhancements that allow it to access foreign filesystems and act on their files. It can mount DOS/Windows partitions on the system’s hard disk, or access files and printers shared by Windows servers on the network, as we explored in “Sharing Files with Windows Systems (Samba)” in Chapter 15. Linux can also run DOS and Windows applications, using compatibility utilities that allow it to invoke MS-DOS or Windows. It can also access remote systems and run programs on them, using the local keyboard, mouse, and screen for interaction.

We use the term Windows somewhat generically in this chapter to refer to any of the operating systems coming from Microsoft, or those compatible with them. Although Windows NT, Windows 2000, and Windows XP are fundamentally different from the old DOS-based systems (up to and including Windows ME), most of the tools in this chapter can accommodate them all.

One of the most common reasons for needing to run Windows is that it often has better support for new hardware products. If you have installed Windows because you need to use a piece of hardware that is supported by Windows but for which there is no Linux driver, do not despair. Although you may have to wait a while for it, most mainstream hardware devices that are supported by Windows will eventually be supported by Linux, too. For example, Linux drivers for USB devices used to be rare and flaky, but now many common USB devices work just fine on Linux. You can get updated information about which USB devices work on Linux at http://www.linux-usb.org.

You may also need to run Windows in order to use “standard” applications, such as Photoshop or Microsoft Office. In both of these cases, there are free, open source applications (namely, the GIMP, KOffice, and OpenOffice.org) that can match or even outdo their proprietary, closed-source equivalents. However, it is still sometimes necessary to run Windows to obtain access to software products that have no Linux equivalent, or for which the Linux counterpart is not fully compatible.

There are essentially four ways in which Linux and Windows can cooperate:

When Windows and Linux are running on separate hardware, and the systems are not networked, a floppy disk or CD (either CD-R or CD-RW) can be written on one system and read on the other. Both Windows and Linux have the capability to read and write CDs in industry-standard, ISO 9660 format. The cdrecord program, which runs on Linux and other Unix flavors, can create CDs using Microsoft’s Joliet extensions to the ISO 9660 standard, making Windows feel right at home with the disk format.

A more cost-effective approach is to install both Windows and Linux on the same computer, each in its own disk partition. At boot time, the user is given the choice of which operating system to run. “Booting the System,” in Chapter 17, tells you how to configure a multiboot system. You can then mount your Windows partition directly onto the Linux filesystem and access the Windows files in a manner similar to regular Unix files.

For networked computers, the most outstanding tool for getting Linux and Windows to cooperate is Samba, an open source software suite that lets you access Unix files and printers from Windows. Linux servers running Samba can—depending on the circumstances—serve Windows computers even faster than Windows servers can! In addition, Samba has proven to be very stable and reliable.

The Samba package also includes programs that work with the smbfs filesystem supported by Linux, which allows directories shared by Windows to be mounted onto the Linux filesystem. We discuss the smbfs filesystem and Samba in enough depth to help you mount shared directories and get a basic, functional server running.

Emulators or virtual computers are forms of software that let you run Windows applications directly under Linux, or even run Windows itself. Wine is an open source project with the goal of directly supporting Windows applications without needing to install Windows. Another approach is used by the commercial VMware application, which is able to concurrently run a number of installations of Windows, Linux, FreeBSD, or some other operating systems. When running Windows under VMware, data is shared with the Linux host using the Samba tools.

Finally, remote desktop applications let users on one system log in to other systems and run applications there, or even control the remote systems.

You should be a little skeptical of some claims of compatibility. You might find, for example, that you need twice the disk storage in order to support two operating systems and their associated files and applications programs, plus file conversion and graphic-format conversion tools, and so on. You may find that hardware tuned for one OS won’t be tuned for the other, or that even when you’ve installed and correctly configured all the necessary software, small compatibility issues remain.