Running UNIX and Windows Together on the Same Machine

Terminal emulation and networking allow you to work on your PC and access a UNIX system on a separate computer. This concept is discussed more in Chapter 15. Running UNIX System look-alike software (such as MKS Toolkit) on DOS brings some of the commands of the UNIX System to a Windows environment. However, you may want to have complete Windows and UNIX environments on the same machine for specific computing requirements. You can do this by allocating your disk so that Windows and UNIX each have their own areas on the disk.

Partitioning a Hard Disk for Use by both UNIX and Windows

One way to have access to both systems on the same machine is to create two separate partitions on your hard disk: one for the UNIX System and one for Windows. Within either partition you run the corresponding operating system and have all of its normal features. You can use a UNIX System application at one moment, and then switch over to the Windows partition and run a Windows application.

This approach allows you to use both systems, to move between them, and to have all of the normal features of the system you are using at the moment. Unfortunately, for most UNIX variants, it is cumbersome to move from one operating system partition to the other. To do so you have to switch partitions, shut down the current system, and start up (boot) the other.

If you are using the UNIX System and want to move to Windows, you begin by selecting the active partition on your machine. Similar to using FDISK for partition management on Windows machines, you use the UNIX fdisk command, which brings up a menu that you use to change the active partition. (Note that to use fdisk you have to have superuser permission.) For example,

 $ su Password: # fdisk

 Hard disk size is 4035 cylinders                                           Cylinders      Partition   Status    Type      Start   End   Length    %      =========   ======    ====    =====   =====   ======   ===          1                 FAT32         0  1181     1182   31          2       Active    UNIX Sys   1182  4034     2852   69 SELECT ONE OF THE FOLLOWING:      1. Create a partition      2. Change Active (Boot from) partition      3. Delete a partition      4. Exit (Update disk configuration and exit)      5. Cancel (Exit without updating disk configuration) Enter Selection: 2 Enter the number of the partition you want to boot from (or enter 0 for none): 1

This sets the computer hardware so that the next time you boot, it will start up in the DOS partition.

After changing the active partition, shut down your UNIX System. To shut down the system, follow one of the methods described in Chapter 13, using either the menu-based system administration commands or the command-line sequence. If you boot the system following the previous steps, it will come up running DOS in the DOS partition.

In addition to the complexity involved in moving between two systems this way, using separate partitions for each system has some important limitations because each partition with the programs and files it contains is independent of the other. In most cases, without special software, you cannot directly move files or data between partitions, and you cannot send the output of a DOS command to a UNIX System command.

VMware

VMware (http://www.vmware.com/) is a virtual machine environment that is fast becoming the de facto standard for operating system emulation. VMware allows Windows (and other operating systems) to coexist on the same physical Linux machine without partitioning, through hardware emulation. Hardware emulation is where each operating system has its own virtual area on a system that consists of a processor, memory, disks, and I/O devices. All devices are accessed through the underlying host operating system, and the file system may be a virtual drive that is contained in a file. It may directly access one or more standard File Allocation Table (FAT) 16 or FAT 32 partitions. All access to Linux file systems is done through Samba open-source file and print server software, which supports Windows clients. (A “lite” version of Samba is included.)

VMware can support multiple operating systems on the same machine, depending on the features of the machine: the more memory and disk space and the faster the processor you have, the better chance you have of running multiple operating system sessions. However, only one operating system can be designated as the host operating system. All of the others run as guests on the virtual machine.

Each operating system has its own group of configuration files that must be loaded initially with the operating system. While VMware supports a wide range of devices and options, you need to plan your requirements carefully to ensure that the configuration you end up with is a useful one. Once the operating system is loaded, you can then load VMware Tools to help manage the virtual machine environment.

One of the problems that VMware solves is the need to perform dual booting. Dual booting is an environment where each operating system on the machine has its own partition and set of instructions as to how the operating system should be loaded. Linux users should be familiar with the LILO boot loader, and Windows users with the NTLDR boot loader. In order to move between the two environments, the machine must first be shut down from the first environment, and then rebooted to the new environment. While this is acceptable for occasional movement from one operating system to the other, it becomes bothersome to do this frequently VMware allows faster switching from one environment and-if your machine has enough physical resources-can actually leave the operating system that you designate as the host operating system running while you move to the other environment.

VMware is available as a commercial product but also comes with a few Linux distributions that include the VMware product as part of the install. Therefore, you have the choice of installing VMware on the distribution of your choice or using their prepackaged distribution.