Explain how to migrate a UNIX application to a Linux system

Introduced

Do you know that linux® is now the world's second server operating system? Today, does your application run on Linux? If not, this article will give you tips and tricks to guide you when porting your application to Linux. This article is based on the experience of software engineers who come from independent software vendors (independent Software VENDORS,ISV) and IBM® laboratories around the world who are involved in many projects that migrate applications to Linux.

First we describe the characteristics of Linux and its specific value in developing and managing applications. Next, we will review the important issues and give a migration guide that contains the major steps for porting. Finally, we take IBM ~ zseries™ as an example to show you how easy it is to migrate from one Linux platform to another. (the word zSeries refers to s/390® and zSeries.) ）

Characteristics and value of Linux

Openness means application flexibility: Linux is the real open system, which makes application portability a reality. In many cases, a simple recompile can bring the application into Linux. This rapid migration gives you real flexibility when optimizing your development and deployment platform.

Multiple hardware support means platform flexibility: Linux can run on almost all known processors, either RISC or cisc,32 bit or 64-bit. It covers all types of computers, from mainframe servers (IBM ~ zSeries) to powerpc®, Sun®ultrasparc, Alpha, Pa-risc, and Intel processors, and down to personal digital assistants and embedded systems. In particular, all IBM ~ Brand servers support Linux.

The availability of source code means its own flexibility: Unlike most commercial software, which is distributed in binary form, the Linux kernel's source codes are available. You can get the source code and then modify and recompile it to meet your specific requirements. Debugging and problem solving or adding new features is no longer dependent on any vendor. You can make the changes you want as long as they conform to the requirements of the GNU general public License.

Serious design means security: Linux security is built from the kernel, and because the code that implements it is tested by tens of thousands of developers, weaknesses are found early. There are many routing and firewall features built into Linux.

Popularity means the existence of skills: Because Linux is popular in universities and colleges, most new graduates have Linux experience. You can almost find people in the Linux user group in any city who can use Linux well, and Web sites and Internet newsgroups remain a valuable and effective source of information and informal technical advice for Linux usage guidelines.

Important issues to consider before you start

Porting to Linux can be easy, simple, and straightforward, especially when your UNIX® application is written in accordance with publicly open standards. If you think porting to Linux is attractive, you need to analyze the potential costs and risks involved in porting and how to reduce them.

Will migration involve huge initial investments?

Cost-is the transplant going to involve huge initial investment in time, people and money? Will the project freeze all other new jobs and consume the resources of the entire team? Do you need to pay a large amount of capital and retraining costs in advance? Is this a very risky proposition: once you start, either you finish it or you fail completely?

Porting to Linux is manageable-the Porting Guide section of this article describes how to migrate step-by-step and each intermediate step itself is stable. This allows you to manage costs, people, and projects based on your priorities. This means that you can complete each step independently and recalculate your priorities and goals after each step. The result is that risk is more manageable and has less impact on your company.

How much is the cost? How long will it take?

Time and money--a comprehensive estimate of your application based on and porting factors: