Nov 16, 2008


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Mar 8, 2008


Linux's History

Linux has a rich history. It is essential to understand Linux's history in order to understand the philosophy behind Linux's programming. This guide hopes to cover what Linux is really about, show you its history, why it was formed, and a brief description of its capabilities and how it operates.

What is Linux?
Linux is a freely distributed operating system that behaves like the Unix operating system. Linux was designed specifically for the PC platform and takes advantage of its design to give users comparable performance to high-end UNIX workstations. Many big-name companies have joined the Linux bandwagon such as IBM and Compaq, offering systems pre-installed with Linux. Also, many companies have started Linux packages, such as Red Hat, Corel, and Samba. However, they can only charge for services and documentation packaged with the Linux software. More and more businesses are using Linux as an efficient and more economical way to run their networks.

Linux is a complete multitasking, multi-user operating system that behaves like UNIX in terms of kernel behavior and peripheral support. Linux has all the features of UNIX and boasts of its open source code and mainly free utilities.

The Linux kernel was originally developed for the Intel 80386, which was developed with multitasking as one of its features. The kernel is the lowest-level core factor of the operating system. The kernel is the code that controls the interface between user programs and hardware devices, the scheduling of processes to achieve multitasking, and many other aspects of the system. The Linux kernel is a monolithic kernel; all the device drivers are part of the kernel proper. Despite the fact that most of Intel's CPUs are used with single-tasking MS-DOS, Linux makes good use of the advanced multitasking features built into the CPU's instruction set. Linux supports demand paging, which means that only the sections of a program that are necessary are read into RAM. Linux also offers support for copy-on-write, a process that if more than one copy of a particular application is loaded, all tasks can share the same memory. When large memory requirements are needed and only small amounts of physical RAM are available, Linux has another feature called swap space. Swap space allows pages of memory to be written to a reserved area of a disk and treated as an extension of physical memory. By moving pages between the swap space and RAM, Linux can, in effect, act as if it had much more physical RAM than it does, with the cost of some speed due to the hard drive's slower access. Linux also supports diverse file systems, as well as those compatible with DOS and OS/2. Linux's file system, ext2fs, is intended for best possible use of the disk.

The History of Linux
Linux is a freely distributable version of UNIX. UNIX is one of the most popular operating systems for networking worldwide because of its large support base and distribution. Linus Torvalds, who was then a student at the University of Helsinki in Finland, developed Linux in 1991. It was released for free on the Internet and generated the largest software-development phenomena of all time. Because of GNU software (GNU being an acronym for Gnu's Not UNIX) created by the Free Software Foundation, Linux has many utilities to offer. The Free Software Foundation offers royalty-free software to programmers and developers. From the very beginning, Linux has been entwined with GNU software. From 1991, Linux quickly developed on hackers' web pages as the alternative to Windows and the more expensive UNIX systems. When Red Hat released its commercial version of Linux packaged with tech support and documentation, the floodgates broke and the majority of the public became aware of Linux and its capabilities. Now more and more new users are willing to try Linux on their personal PCs and business users are willing to use Linux to run their networks. Linux has become the latest phenomenon to hit the PC software market.

Linux is a unique operating system in that it is an active participant in the Open Source Software movement. Linux is legally covered by the GNU General Public License, also known as GPL. Open Source software is free but is not in the public domain. It is not shareware either. GPL allows people to take free software and distribute their own versions of the software. However, the vendors who sell free software cannot restrict the rights of users who purchase the software. In other words, users who buy GPL software can make copies of it and distribute it free of charge or for a fee. Also, distributors of GPL software must make it clear that the software is covered by the GPL and must provide the complete source code for the software at no cost. Linux embodies the Open Source model. Open source applies to software for which the source code is freely available for anyone to download, alter, and redistribute. Linux is the perfect operating system for hackers because they can freely download newer versions of the Linux kernel or other Linux utilities of the Internet and instantly change its source code to fix any software bugs found. That way, bugs can be fixed in a matter of hours as opposed to days and weeks. Beta testers and code debuggers are unorganized and spread throughout the world, but surprisingly, they have managed to quickly debug Linux software efficiently and cooperate online through the use of the Internet.

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