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What is Linux? Why is it important?
Linux is an open source version of the Unix operating system. Originally developed in 1991 by Finnish graduate student Linus Torvalds, Linux has been developed collaboratively over the Internet with thousands of programmers contributing code to the system.
Linux is a modern operating system. This means that it runs on 32-bit architecture, uses preemptive multitasking, protected memory, supports multiple users, and has rich support for networking, including TCP/IP networking. Linux was originally written for Intel's 386 architecture, but now runs on a wide variety of hardware, including the full x86 family of processors, as well as Alpha, SPARC, and PowerPC chips.
Linux runs all the applications a Unix server system should run, including web servers like Apache, mail serving software like Sendmail, and database servers like Oracle, Informix, or more open applications like MySQL and Postgres. Linux supports a wide range of file system types, and through programs like Samba can even seamlessly replace NT as a Windows file server. Through the use of clustering technology, Linux can scale up to handle the supercomputing loads required by many scientific/engineering applications, and required in high availability environments.
Why Linux is important
Most servers today run some variant of the Unix operating system. Linux is the most widely installed Unix variant, and also the variant with the most rapidly growing market share. Linux's remarkable growth and popularity stem from several factors:
Flexibility The source code to the Linux kernel is copyrighted under the GNU Public License, meaning that the system must be freely distributed with source code available, and anyone may freely modify that source code provided that any modifications they distribute are distributed with source code. Because the source to Linux is open, it is easy to customize. This flexibility has enabled Linux to run on everything from handhelds and embedded systems to clusters of hundreds of servers working in concert.
Reliability Because the source code to Linux is open and widely distributed, Linux has been thoroughly debugged. Each new version of the operating system is rapidly viewed and tested by thousands of programmers world wide, aptly demonstrating the adage that "given enough eyeballs, all bugs are shallow."
Linux's fundamental architecture also creates a more reliable system. Systems using protected memory and preemptive multitasking are inherently more stable. Protected memory prevents an error in one application from bringing down the entire system, and genuine multitasking means that a bottleneck in one application does not hold up the entire system. Linux also maintains a very clean separation between user processes and kernel processes. While other server class operating systems use protected memory, protected memory does no good if faulty applications are allowed to invade kernel space with their processes.
Economy Because Linux is open source, the initial cost is low. There are no seat licenses, no usage fees associated with the operating system. Linux is also designed for Intel architecture, meaning that it runs powerfully and efficiently on the most inexpensive hardware capable of performing server-class operations.
The real cost savings with Linux, however, comes from total cost of ownership. Updates happen rapidly and openly, so users are not held hostage to a vendor's release schedule. Support is available from a legion of open source programmers, or from a number of commercial supporters of Linux. The result is that bugs are identified and fixed more rapidly, new features are brought on line more quickly, all at a lower up front cost, dramatically reducing the total cost of ownership.
The Power of Open Source
Linux may be the best example, but it is only one example, of the power of open source. Collaborative, networked development is a new model of software development made possible by the Internet. The full power of this collaborative method can only be realized when the source code to software is freely shared among developers.
Open source accelerates the development process. It breaks down the barriers between developers and users, and removes obstacles in developer-to-developer communication. In today's Internet economy, these kinds of accelerators have become not just a business advantage, but a business necessity.
The proof of the open source model is in the results: Apache holds roughly 60% market share among web servers, and that market share is growing. Sendmail holds roughly 80% market share among mail transfer agents. Linux is the fastest growing server-class operating system.
Other Resources
To learn more about open source principles and the open source development model, look at the Open Source Initiative (http://www.opensource.org).
To learn more about Linux, look at Linux.com (http://www.linux.com).
To see the collaborative, networked development process in action,
look at Source Forge (http://www.sourceforge.net).
