-In Sept 1991, LinusTorvalds, a second year student of Computer Science at the University of Helsinki, developed the preliminary kernel of Linux, known as Linux version 0.0.1, Linux is open source free software which is based on UNIX. The defining component of a Linux-based operating system is the Linux kernel,-----------------------------------------------It was licensed under GNU General Public License, thus ensuring that the source codes will be free for all to copy, study and to change. Aim at developing a complete Unix-like operating system which is free for copying and modificationCompanies make their money by maintaining and distributing the software-------------------------------------------------------Linux has been used for many computing platformsPC, PDA, Supercomputer,… Not only character user interface but graphical user interface is available700 MHz processor (about Intel Celeron or better)512 MiB RAM (system memory)5 GB of hard-drive space (or USB stick, memory card or external drive but see LiveCD for an alternative approach)VGA capable of 1024x768 screen resolutionEither a CD/DVD drive or a USB port for the installer mediaInternet access is helpful-------------------------------------In order to encourage wide dissemination of his OS, Linus made the source code open to public. At the end of 1992 there were about a hundred Linux developers. Next year there were 1000. And the numbers multiplied every year. Recent estimates say about 29 million people use Linux worldwide. ------------------------------------Free software, as defined by the FSF (Free Software Foundation), is a "matter of liberty, not price." To qualify as free software by FSF standards, you must be able to: Run the program for any purpose you want to, rather than be restricted in what you can use it for. View the program's source code. Study the program's source code and modify it if you need to. Share the program with others. Improve the program and release those improvements so that others can use them. --------------------------------
Kernel: the part of os where the real work is done. firewall is a part of kernel.Acts as intermediary between the computer hardware and various programs.----------------------------------------Linux kernel uses command line interface:-Command line interface(cli) terminalAdministrative tool-Graphical user interface(gui)Looks different on each version of LinuxEasy controls and applicable contentsEasy use of multimedia contents---------------------------------------------------------------Contains the driver support for the pc hardware.Contains advanced=متقدّم memory management features support for many different types of file systems.---------------------------------------Dynamic loading of kernel modulePreemptive=وقائيSymmetric multiprocessor support.
Red hat linux:most common distribution used with tools useful in any linux environment ,two type :enterprise and fedoraSuselinux:offer software packages for almost any business needs it.Slackwarelinux: many features similar to unix it is commonly used in multiprocessor environments due to its enhanced multiprocessor support it.Debianlinux:offers largest number of packages of all linux.Turbo linux: Mandrake linux:similar to red hat with enhancements for ease of use.Gentoo Linux : Gentoo is a specialty distribution meant for programmers.
Server:handles communication between hardware and softwareClient: display graphics and graphical frontendsWindow manager: basic window functionality (menu)Desktop: (kde,gnome,…)
The program must be freely distributed (It can be part of a package that is sold though, such as Red Hat has done with Linux in the example below).Source code must be included.Anyone must be allowed to modify the source code.Modified versions can be redistributed.The license must not require the exclusion of other software or interfere with the operation of other software
Android is a version of Linux operating system designed primarily for touchscreen mobile devices such as smartphones and tablet computers.2. Android is developed for Mobile Internet Devices and mobile phones whereas Linux is developed for desktops/laptops/servers.3. The Android operating system has its own C library called Bionic whereas Linux systems use GNU C library.4. The Android systems use flash memory instead of hard drives while the standard Linux systems use magnetic drives.5. The Android systems have their own power manager whereas the Linux systems use APM and ACPI to manage the power.(Most of the Linux distributions use the GNU C library to caterلتَلْبِية to the library routine needs. The Android Operating system has its own C library known as Bionic which is designed to provide quick execution paths and to avert edge cases.)
