Introduction to Linux
In this chapter we will explore the evolution of Unix and popular operating systems. Linux is the registered trademark of Linus Torvalds in the U.S. and other countries.
Linux is Open source operating system what that means?
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The code that powers Linux isn’t owned by any organization and company, instead it is developed by the community that uses it. It frees users from licensing costs & allows the code to be modified to meet changing needs.
Linux Evolution and Popular Operating Systems
Linux means the kernel of the system, which is the central controller of everything that happens on the computer. Hardware and Software interact with each other with the help of kernel. UNIX was originally an operating system developed at AT&T Bell Labs in the 1970’s. Only software that has been certified by the Open Group may call itself UNIX. Linux has not been certified, so Linux really isn’t UNIX! It’s just UNIX-like.
Role of the Kernel in Linux
The kernel of the operating system is like an air traffic controller at an airport. The kernel dictates which program gets which pieces of memory, it starts and kills programs, and it handles displaying text on a monitor. It allocate the memory to the processes on behalf of their needs. When an application needs to write to disk, it must ask the operating system to do it. If two applications ask for the same resource, the kernel decides who gets it, and in some cases, kills off one of the applications in order to save the rest of the system.
When the computer starts up it loads a small piece of code called a boot loader. The boot loader’s job is to load the kernel and get it started. If you are more familiar with operating systems such as Microsoft Windows or Apple’s OS X, you probably never see the boot loader, but in the UNIX world it’s usually visible so that you can tweak the way your computer boots.
The kernel also handles switching of applications. A computer will have a small number of CPUs and a finite amount of memory. The kernel takes care of unloading one task and loading a new task if there are more tasks than CPUs. When the current task has run a sufficient amount of time, the CPU pauses the task so that another may run. This is called pre-emptive multitasking. Multitasking means that the computer is doing several tasks at once, and pre-emptive means that the kernel is deciding when to switch focus between tasks. With the tasks rapidly switching, it appears that the computer is doing many things at once.
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