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UNIX-Like Operating Systems

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UNIX-Like Operating Systems History OS UNIX UI UNIX-like Security Questions Operating Systems by Roman Szturc Simple, Low-Power Machines History user had sole use of the machine, OS program was loaded into the machine and the UNIX machine set to work, UI task is responsible for everything, Security Questions task totaly determines behavior of computer. machines came with libraries of support code which were linked to the user’s program to assist in operations such as input and output This would become the genesis of the modern-day operating system. More Powerful Computers History Later, more powerful computers appeared. They were OS characterized as follows: UNIX UI CPU is much faster than R/W operations, Security CPU is idle while R/W operation in progress, Questions CPU can perform other task while idle. Need to manage multiple tasks Task switching. Task scheduling. Operating System History OS An operating system (OS) is the system (low-level) UNIX UI software responsible for Security Questions direct control and management of hardware, task management, storage allocation, presentation of a default user interface. Program and Process process2 History OS data2 UNIX UI Security process1 Questions data1 PSfrag replacements program code memory Early Operating Systems History OS Early OS had some problems. The OS UNIX UI were very diverse — each OS specific to particular Security hardware, Questions used radically different models of commands and procedures, Typically, each time the manufacturer brought out a new machine, there would be a new OS. UNIX UNIX is an OS developed in the 1960s and 1970s by AT&T Bell Labs employees including K. Thompson, D. History Ritchie, and D. McIlroy. It was designed to be OS UNIX portable, UI multi-tasking and Security multi-user. Questions The UNIX systems are characterized by various concepts: plain text files, command line interpreter, hierarchical file system, treating devices and certain types of inter-process communication as files. Unix Architecture History OS UNIX UI shell utilities Security PSfrag replacements Questions kernel hardware Unix-like systems History OS UNIX UI Security Questions UNIX Philosophy There are the following ideas characterizing the UNIX philosophy: History OS write simple parts connected by clean interfaces. UNIX clarity is better than cleverness, UI Security design programs to be connected to other Questions programs, separate policy from mechanism; separate interfaces from engines, when a program has nothing surprising to say, it should say nothing, when you must fail, fail noisily and as soon as possible, design for the future, because it will be here sooner than you think. File System History OS UNIX Every item in a UNIX file system can de defined as UI belonging to one of four possible types: Security Questions ordinary file, directory, special file, links. Pipe History A pipe “|” sends data from standard output of source OS process to standard input of destination process. UNIX if [ $(wget -O - http://www.vltava.cz/... UI | grep -c "Perl") -gt 0 ]; then Security mail -s "Book" [email protected] << EOF Questions You can order the Perl book at vltava.cz. Your book notifier . EOF fi User Interfaces One of the most heated and ancient battles is over the choice of Graphical User Interface (GUI) vs. Command History Line Interface (CLI). OS UNIX Advantages of CLI UI Security structure of UNIX and of its shells allows powerful Questions mechanisms of piping and redirection, porting CLI utility to other system is relatively easy task, CLI utilities incur much less size and speed overhead than their graphical counterparts, textual information is also much smaller than graphical, obviously making remote connections less of a pain in the neck. User Interfaces (continued) History Advantages of GUI OS prettier and more natural feel, UNIX UI modern computing is very much focused on Security media and that is naturally only done with Questions graphical environments, graphical desktop allows true multitasking (for the user) to take place, an important benefit is the display of dynamically modifiable abstract information — one click can replace several commands. User Interfaces (continued) History Learning Curve OS UNIX ability to UI use an OS Security Questions CLI PSfrag replacements GUI time X Window System X display (Windows) Solaris X screen History X client X server OS UNIX UI net Security Questions AIX X display (Linux) PSfrag replacements X client X server X screen X client X screen X client Window Managers and Desktops Window Manager History A window manager is software that controls the OS placement and appearance of application windows UNIX under the X Window System. The most popular ones UI are: AfterStep, Enlightenment, WindowMaker, Security Metacity, TWM, Kwin, MWM, FWM, IceWM, Sawfish, . Questions Desktop A desktop consists of what is on the screen before any windows are opened, and what reappears when windows are closed. It usually shows icons for programs, documents or folders and possibly an image as wallpaper. The most popular ones are: GNOME, KDE, XFCE, CDE. Security History Security is inherent part of multiuser OS. It grants OS privacy of user data OS stability. UNIX UI Authentication Security is process by which a computer attempts to Questions ensure that users are who they say they are. Authorization is a process that protects computer resources by only allowing those resources to be used by resource consumers that have been granted authority to use them. UNIX Distributions Over the years there were more than 250 versions of History UNIX-like systems released. The following are the OS most significant ones: UNIX UI (Net,Free,Open)BSD Security Questions Darwin Mac OS X (Open)Solaris Linux z/OS Unix V1R7 AIX IRIX Leading Areas History OS UNIX UI Internet backbone, Security multiprocessor systems, Questions critical applications, need of extremely high up-time, Questions History OS There are several frequently asked questions UNIX concerning UNIX systems. UI Security UNIX is more than 30 years-old. Is it worth to Questions linger with such an antique? Is UNIX dangerous? Why should I type a complicated commands instead of select menu items? Why UNIX disallows users to do mistakes?.
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