Unix - Anvari.Net

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1.   Creation of Unix
2.   Unix Uniqueness
3.   Unix Architecture
4.   Unix Application
5.   Unix Security
6.   Unix & Web
              Creation of Unix
• What is Unix                 • Unix Creation
                               In late 1960s, Ken Thompson from
Unix is a computer operating   Bell Labs wrote a computer game
system, a control program      on PDP-7, he started with an
that works with users to run   implementation of an earlier file
                               system, then added processes,
programs, manage resources,
                               simple file utilities and command
and communicate with other     interpreter which he called a
computer system.               “shell”. Hence, he created system
                               named “Unix” , however, Unix
                               developed by more and more
                               programmers in the past decades.
            Unix Uniqueness
•   Multitasking Capability
•   Multiuser Capability
•   Multichoice System
•   System Portability
•   Application Libraries
• Unix allows users to do several things at
  once, such as printing out one file while the
  user edits another file.
• This is a major feature for users, since users
  don’t have to wait for one application to end
  before starting another one.
• Unix allows several users to access the
  same document by compartmentalizing the
  document so that the change of one user
  don’t override the change another user.
• Unix can take the commands of a number of
  users---determined by the design of the
  computer—to run program, access file, and
  print documents at the same time.
         Multichoice System
• Microsoft MS-DOS and the Apple
  Macintosh interface are easy to use as both
  of them are designed to give the users less
  power, both have fewer command

• Unix is a multichoice system, as an
  example, Unix has three different types of
          System Portability
• Unix can be moved from one brand of
  computer to another with a minimum of
  code change
• Unix can be upgraded without having all the
  customer’s data inputted again, and new
  version of Unix were backward compatible
  with older version
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        Application Libraries
• From Bell Labs to the universities, every
  computer programmer worth his or her own
  salt started developing programs for Unix
• Today there are hundreds of Unix
  applications that can be purchased from
  third-party vendors, in addition to the
  applications that come with Unix
 Unix Architecture(Chart)


Kernel     Shell   Tools & Applications
                  Unix Architecture
• The Kernel controls the hardware and turns part of the system on
   and off at the programmer’s command. If you ask the computer to list
   all the files in a directory, the kernel tells the computer to read all the
   files in that directory from the disk and display them on your screen
• The Shell -- 3 major types of shell: Bourne Shell, C Shell,
  Korn Sell; The purpose of the shell is to act as an interpreter between
  the user and the computer.
• Tools& Applications There are hundreds of tools available to
   Unix users, and tools are grouped into categories for certain functions,
   such as word processing, business applications or programming
                  Unix Applications
• Productivity and office applications
Unix has abandoned productivity applications to the PC world. Computers sold in
   local stores don’t run on Unix
• Small database and client-server applications –Many
   competitors fight in this market, such as Windows NT, Unix, IBM’s AS/400
   etc. Unix competes here using database products that are ODBC-enabled, use
   Java and Web technology and have better management tools for widely
   dispersed situation
• Small technical applications
• Large commercial applications and database
  Unix is powerful in this market
• Large technical applications
                        Unix Security
There are many choices available to assist in strengthening security of Unix,
   examples are as follows:

• Tripwire tool is used to detect unauthorized changes at a file/directory
   level. It can manage and track changes to key system files by maintaining an
   information database for the specified files.

• Sudo utility lets     the administrator delegate root authority to users without
   sharing the root password.With Sudo, the system administrator can permit
   access to only a small set of commands based on the role performed by a user.

• ssh shell is the preferred tool for remote access to system resource by many
   system administrators today. ssh uses public-key crytography to establish a
   secure channel of communication over public networks such as the
   Internet.There is a server side and a client side to ssh.
                     Unix & Web
• During these years, it was widely reported
  that Windows NT was expected to bludgeon
  Unix into the OS oblivion.Is that true?
• It is not likely.Using Apache as an indicator of the Unix
  presence on the web and Microsoft’s Internet Information Server(IIS)
  for NT to compare, the statistics shows that Apache increased sales
  from 15,797 server sites in 1996 to more than 827,000 in 1999, while
  IIS from no presence in 1996 to more than 381,000. Keep in mind
  these Apache servers are only a fraction of the total number of Unix
  servers on the web.

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