You need to learn how to use Linux. And the best way to get Linux training is to work with it and get real, practical Linux experience. There are lots of different ways to get Linux, and lots of different versions of Linux to choose from!

You can get a version of Linux, also known as a Linux distribution (or distro for short), on CD or DVD. You can also download a Linux ISO file and burn it to CD or DVD yourself. Linux Tips: If you decide to download Linux as a Linux ISO file, keep in mind that these files are very large. Linux CD ISO files are about 700 MB and Linux DVD ISO files are about 4 GB (almost six times the size of a CD!). Therefore, only download Linux if you have high-speed Internet access.

Linux Tips: You can do an Internet search for “list of linux cds” or “list of linux dvds” and buy the Linux OS and have it delivered to you by mail very cheaply.

Some Linux distros are available as “installation” versions and some are available as “live” versions - and some are available as both!

An installation version of Linux may be on just a one CD / DVD or it may require more than one. However, a Linux live CD or a Linux live DVD version consists of just a single CD or DVD.

Linux Installation Versions

You boot a computer system with a Linux installation CD / DVD to run the Linux installation routine and install Linux on a system. This could be a system that doesn’t have an operating system on it - or it could be one that does have an operating system on it, such as the Windows operating system.

If you install Linux on Windows, you create a “dual boot” (Linux and Windows) system. Then after the Linux installation, you can either boot the system into Windows or boot it into Linux, but not both at the same time.

When you install Linux from CD or DVD onto a computer system, you run the Linux installation routine and do several steps to put the Linux OS and Linux software programs on the hard disk in a system permanently, although you can remove Linux later if you need to.

After you install Linux, you boot to Linux from the hard disk in the system. At this point, the Linux desktop appears and you can do a few simple steps to open a terminal emulation window. This allows you to go to the Linux command line so you can run Linux commands - the best way to learn how to use Linux.

Linux Live Versions

Linux live CDs or DVDs are used to run Linux “live”, for as long as the power is turned on.

To run a Linux live version, you set your system up to boot from the live CD or DVD. Then you start your system with the Linux live CD / DVD in your drive. No installation is required!

After you boot with a Linux live CD / DVD, the entire Linux OS (operating system) boots and runs automatically. At this point, you see a Linux desktop on the screen and you can run Linux software programs.

At the Linux desktop, you can also do the steps to open a terminal emulation window. This allows you to work at the Linux command line as the root user and run Linux commands. And learning to run Linux commands is the best way to learn how to use Linux and do Linux system administration.

Written by Clyde Boom.

When you write data, it doesn’t necessarily get written to disk right then. The kernel maintains caches of many things, and disk data is something where a lot of work is done to keep everything fast and efficient. That’s great for performance, but sometimes you want to know that data really has gotten to the disk drive. This could be because you want to test the performance of the drive, but could also be when you suspect a drive is malfunctioning: if you just write and read back, you’ll be reading from cache, not from actual disk platters.

So how can you be sure you are reading data from the disk? The answer actually gets a little complicated, particularly if you are testing for integrity, so bear with me.

Obviously the first thing you need to do is get the data in the cache sent on its way to the disk. That’s “sync”, which tells the kernel that you want the data written. But that doesn’t mean that a subsequent read comes from disk: if the requested data is still in cache, that’s where it will be fetched from. It also doesn’t necessarily mean that the kernel actually has sent the data along to the disk controller: a “sync” is a request, not a command that says “stop everything else you are doing and write your whole buffer cache to disk right now!”. No, “sync” just means that the cache will be written, as and when the kernel has time to do so.

Traditonally, the only way to be sure you were not reading back from the cache was to overwrite the cache with other data. That required two things: knowing how big the cache is at this moment, and having unrelated data of sufficient size to overwrite with.

On older Unixes with fixed sized buffer caches, the first part was easy enough, and since memory was often expensive and in shorter supply than it is now, the cache wasn’t apt to be all that large anyway. That’s changed radically: modern systems allocate cache memory dynamically and while the total cache is still small compared to disk drives, it can now be gigabytes of data that you need to overwrite. http://www.zerivista.com

Written by azerivista.com Miller.

Linux is an operating system much like Windows and MacOSs, but is free and adaptable by any of its users.

Linux is an operating system, a piece of software that interfaces with the computer’s hardware on one side and the user (or programs being run by the user) on the other. Two common examples of operating systems are the ubiquitous Microsoft Windows and Apple’s MacOS. Linux is a member of a family of operating systems based on one developed in the early 1970’s at Bell Labs. This ancestral operating system was referred to as UNIX (a thinly veiled pun on a previous multi-organization operating system project Bell Labs was part of called MULTICS). UNIX was originally not a commercial product and was spread throughout governmental agencies, educational institutions, and other areas freely. The fact that the system was open (i.e. anyone running it could examine the inner workings, learn from them, and modify them as needed) gave rise to a culture of computer users accustomed to freely available, powerful tools.

Once the inevitable effort began to commercialize UNIX, non-corporate groups arose to keep the open nature of the early UNIX community alive. The foremost group, formed in the early 1980’s by Richard M. Stallman (more commonly referred to as RMS) was the GNU organization (Gnu’s Not Unix, so named to avert potential legal trouble from the owners of the UNIX trademark). The GNU organization began efforts to create a fully compatible “Unix-like” operating system and suite of tools.

In the early 1990’s, a young Finnish computer science graduate student studying in Helsinki named Linus Torvalds decided to create his own implementation of the UNIX operating system. As he was a graduate student with limited fiscal resources, his implementation was designed to run on the cheap computer hardware he had available (an Intel 80386-based machine), and he used the tools made by the GNU organization to build the foundation for his new operating system (which was named Linux, for Linus’s Unix). Linus soon posted to various newsgroups on the Internet about his new project and opened the source to outside participation. Linus’s kernel of an operating system, with the contributions of thousands of computer enthusiasts across the world collaborating through the Internet and using the freely available GNU tools, blossomed soon into a fully featured UNIX implementation running on many kinds of hardware (Intel, PowerPC, Sparc, and many others).

Linux has all the industrial strength operating system features honed over the thirty year lifespan of UNIX, including very stable operation, high performance networking facilities, the ability to multitask efficiently across many programs and many simultaneous users, finely-tuned security mechanisms, and many others. In addition to Linux’s numerous technical strengths, it possesses a large and very active user community that tends to be very supportive of new users.

Linux is used today on machines ranging from handheld computers, to embedded instrumentation, to personal workstations, to the largest mainframes available from IBM. It is available free of charge through the Internet, or for a modest fee on other media (most frequently CD-ROM disks). Thousands of applications ranging from web servers to database engines and programming tools, to word processors to 3d first person shooter games and the popular Netscape web browser, are also available for Linux, many at no cost like their host operating system. Companies and volunteer organizations package up the many components of Linux and a broad selection of the available software into convenient “distributions”, each of which has it’s own individual flavor (analogous to British English and Texan English, each is English, but each has slight differentiating nuances).