1、Linus Torvalds was a student in Helsinki, Finland, in 1991 when he started a project: writing his own operating system kernel. He also collected together and/or developed the other essential ingredients required to construct an entire operating system with his kernel at the center. This soon became known as the Linux kernel.
2、More About Linux History
The Linux distributions created in the mid-90’s provided the basis for fully free computing and became a driving force in the open source software movement. In 1998, major companies like IBM and Oracle announced support for the Linux platform and began major development efforts as well.
Today, Linux powers more than half of the servers on the Internet, the majority of smart-phones (via the Android system which is built on top of Linux), and nearly all of the world’s most powerful supercomputers
1、Every organization or project has a philosophy that works as a guide while framing its objectives and delineating its growth path. This section contains a description of the Linux philosophy and how this philosophy has impacted its development.
Linux is constantly enhanced and maintained by a network of developers from all over the world collaborating over the Internet, with Linus Torvalds at the head. Technical skill and a desire to contribute are the only qualifications for participating.
2、Linux borrows heavily from the UNIX operating system because it was written to be a free and open source version of UNIX. Files are stored in a hierarchical filesystem, with the top node of the system being root or simply "/". Whenever possible, Linux makes its components available via files or objects that look like files. Processes, devices, and network sockets are all represented by file-like objects, and can often be worked with using the same utilities used for regular files.
Linux is a fully multitasking (a method where multiple tasks are performed during the same period of time), multiuser operating system, with built-in networking and service processes known as daemons in the UNIX world.
1、Introduction
Suppose as part of your job you need to configure a Linux file server, and you run into some difficulties. If you're not able to figure out the answer yourself or get help from a co-worker, the Linux community might just save the day! There are many ways to engage with the Linux community: you can post queries on relevant discussion forums, subscribe to discussion threads, and even join local Linux groups that meet in your area.
2、More About The Linux Community
The Linux community is a far-reaching ecosystem consisting of developers, system administrators, users and vendors, who use many different forums to connect with one another. Among the most popular are:
Linux User Groups (both local and online)
Internet Relay Chat (IRC) software (such as Pidgin and XChat)
Online communities and discussion boards
Newsgroups and mailing lists
Community events (such as LinuxCon and ApacheCon)
One of the most powerful online user communities is linux.com. This site is hosted by the Linux Foundation and serves over one million unique visitors every month. It has active sections on:
News
Community discussion threads
Free tutorials and user tips
We will refer several times in this course to relevant articles or tutorials on this site.
1、When you start exploring Linux, you'll soon come across some unfamiliar terms like distribution, boot loader, desktop environment, etc. So let's stop and take a look at some basic terminology used in Linux to help you get up to speed before we proceed further
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1、Suppose you have been assigned to a project building a product for a Linux platform. Project requirements include making sure the project works properly on the most widely used Linux distributions. To accomplish this you need to learn about the different components, services and configurations associated with each distribution. We're about to look at how you'd go about doing exactly that.
2、So, what is a Linux distribution and how does it relate to the Linux kernel?
As illustrated below, the Linux kernel is the core of a computer operating system. A full Linux distribution consists of the kernel plus a number of other software tools for file-related operations, user management, and software package management. Each of these tools provides a small part of the complete system. Each tool is often its own separate project, with its own developers working to perfect that piece of the system.
3、More about Linux Distributions
As mentioned earlier, the current Linux kernel, along with past Linux kernels (as well as earlier release versions) can be found at the www.kernel.org web site. The various Linux distributions may be based on different kernel versions. For example, the very popular RHEL 6 distribution is based on the 2.6.32 version of the Linux kernel, which is rather old but extremely stable. Other distributions may move more quickly in adopting the latest kernel releases. It is important to note that the kernel is not an all or nothing proposition, for example, RHEL 6 has incorporated many of the more recent kernel improvements into their version of 2.6.32.
Examples of other essential tools and ingredients provided by distributions include the C/C++ compiler, the gdb debugger, the core system libraries applications need to link with in order to run, the low-level interface for drawing graphics on the screen as well as the higher-level desktop environment, and the system for installing and updating the various components including the kernel itself.
4、Services Associated with Distributions
vast variety of Linux distributions cater to different audiences and organizations depending on their specific needs. Large commercial organizations tend to favor the commercially supported distributions from Red Hat, SUSE and Canonical (Ubuntu).
CentOS is a popular free alternative to Red Hat Enterprise Linux (RHEL). Ubuntu and Fedora are popular in the educational realm. Scientific Linux is favored by the scientific research community for its compatibility with scientific and mathematical software packages. Both CentOS and Scientific Linux are binary-compatible with RHEL; i.e., binary software packages in most cases will install properly across the distributions.
Many commercial distributors, including Red Hat, Ubuntu, SUSE, and Oracle, provide long term fee-based support for their distributions, as well as hardware and software certification. All major distributors provide update services for keeping your system primed with the latest security and bug fixes, and performance enhancements, as well as provide online support resources.
