How to integrate Linux with Unix

By Opinder Bawa, SCO Group

Computerworld |

The use of the Linux operating system is becoming more common throughout the IT industry. Many corporate IT departments are using Linux to complement existing Unix systems using special-purpose Linux servers on company networks in areas s

uch as file and print services and Web services.

The question many IT administrators face is where and how to begin integrating Linux and Unix. While each IT department will have its own needs, I will explain a few simple approaches for beginning to use Linux and Unix together to strengthen and enhance a corporate IT strategy.

Multihosted operating systems and shared storage

The simplest approach to learning Linux while still maintaining the Unix operating system is to install both operating systems on the same machine. This allows the user to learn Linux while sharing its file systems and data with the Unix operating system. The two can coexist and boot independently of each other by using the boot managers that are included with Linux, such as the Grub or LILO boot loaders. Be sure to note that when you install both Linux and Unix on the same computer, Unix should be installed first. For more information on using Grub or LILO see www.gnu.org/manual/grub/html_mono/grub.html or http://docsrv.caldera.com/LateNews
/osT.unixware7_linux.html.

Unix and Linux can share storage and file systems in a variety of ways. The two operating systems can be installed on the same server and can share storage in this way. However, in a networked environment with many users, a more efficient way to share storage is to set up a network file system, such as an NFS or Samba share. The documents located at the following URLs offer information on configuring NFS or Samba on Linux: http://tldp.org/HOWTO/NFS-HOWTO/index.html and http://tldp.org/HOWTO/SMB-HOWTO.html.

Virtual OS hosting

Another approach to integrating Linux with Unix is to virtually host one operating system on another by using a commercial product such as VMware. In this way, the host operating system can run a separate operating system within it, providing access to all the systems' resources, allowing both native applications on the host operating system and applications on the guest operating system to run side-by-side. It's possible using these virtual hosting utilities to set up a system with a Linux host operating system and an x86-based Unix operating system as the guest operating system, where the Unix operating system runs in a Linux session.


	Opinder Bawa is senior vice president of technology and development at SCO Group Inc. (formerly Caldera International Inc.), where he is responsible for integrating corporate vision and technology strategy. He has close to 20 years of industry experience, including serving as director of IT at 3Com Corp., as well as technology and management posts at Citibank, IBM and Toshiba.

Linux applications on Unix

A number of Unix systems provide source-code compatibility with open-source technologies that allow Linux applications to be ported to them. Many Unix operating systems provide a complete Linux environment that allows Linux applications, including Apache Web Server, Oracle 9i and K Desktop Environment, to run unmodified. There is no emulation layer, so no performance is lost. In fact, in some cases the performance is better than on native Linux itself. This capability is becoming more common on modern Unix platforms as the popularity of Linux and its applications increases. For more information see www.sun.com/software/solaris/ds/ds-linux/index.html or www.sco.com/products/openunix/lkp.

Unix applications on Linux

Because of their common roots, Unix applications port with relative ease to Linux. It's also possible to run Unix applications directly on a Linux platform without porting. This is accomplished using the linux-abi facility, which is included with most Linux distributions today. Linux-abi enables the Linux kernel to execute a range of x86 binary types. The Linux kernel that has linux-abi enabled will require loadable modules built for it. The linux-abi source can be downloaded from Sourceforge.net at http://linux-abi.sourceforge.net or www.pcunix.com/Linux/linuxabi.html. Unix binaries that don't use shared libraries may run without any further support, but for some executables, it's necessary to obtain shared runtime libraries from the Unix vendor. Many modern Unix vendors will offer these for use on the Linux operating system for a modest fee. Remember, always check to see if the code you are using is licensed. If it is, comply with the license.

Tips for integrating Linux and Unix:

Decide what needs to be accomplished using the Linux operating system. Why do you need it? Where do you need it? How will you educate yourself on Linux?

Develop a plan to learn the Linux operating system. There are many educational programs offered by corporations and institutions. For more information on some of the training that is offered, see these Web sites: SCO.com, RedHat.com and the Linux Professional Institute.

Start small. Replace one server, such as a Web server or a file and print server, with the Linux operating system. Try it out and see how it works for you.

Contact the necessary vendors and gather the binaries and source code needed to allow Unix applications to run on Linux and Linux applications to run on Unix.

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