os_unix by gegeshandong



• A computer system consists of
    hardware
    system programs
    application programs
  History of Operating Systems (1)

Early batch system
    bring cards to 1401
    read cards to tape
    put tape on 7094 which does computing
    put tape on 1401 which prints output
  Computer Hardware Review (1)


• Components of a simple personal computer
            Type of Computers

• Supercomputing: used for scientific computing
• Mainframes: used to be primary form of computer, used in centralized
  computers, used in businesses for timesharing
• Servers: computers used to connect other computers to the internet,
  printer, file sharing, etc.
• Desktops: Personal Computers
• Workstations: More powerful version of the personal computer
• Handheld: Smaller operating Systems for handhelds
• Real Time: Operating Systems for information that needs to be
  updated in real time
• Embedded Systems: Systems that are found within another System
           History of Operating Systems

                        • First Operating System
•   Originally developed in AT&T Bell Labs (now know as Lucent
•   UNIX was taken to University of California Berkley leading to the
    foundation of the Berkeley Standard Distribution
•   UNIX then opened up the computer industry to many other UNIX type
    operating systems and more
•   To date, Apple MAC OS X is the most widely used desktop version of
          Types of Operating Systems


• Linux

• Windows


                   Go on to next page

• Free UNIX-type operating
• Linus Torvalds started creating
  in 1991
• Started out as MINIX then
  formed into Linux
• Continuously updated
• Popular among college students
• Intended for small servers,
  workstations, desktops, and
• Cost: Free
           What is Unix?

A fully featured modern operating system
It is available in a variety of “flavors.”
It’s comprised of simple tools that perform a
single function well.
These tools can be used together to perform
complex tasks.
       A Little History First: UNIX
• Initial design by Ken Thompson, Dennis
  Ritchie and others at AT&T's Bell Telephone
  Laboratories (BTL) in 1969: 32 years ago!
• AT&T made the source available to
  Universities for research and educational use.
• 1973 UNIX was rewritten in C resulting in
  Version 4.
  The C language was also originally designed and
   developed for use on the UNIX system by Dennis
  C was evolved from 'B', developed by Thompson.
• Interactive Systems first commercial (1977)
• Microsoft and SCO release XENIX (1980)
• 1982 Bill Joy left Berkeley and founded Sun
    SunOS originall based on BSD 4.2
    SunOS 5 (Solaris 2.X) was a collaborative effort based on
     System V, release 4 (SVR4).
• AIX from IBM
• HP/UX from Hewlett Packard Corporation
• ULTRIX from Digitial Equipment Corporation, followed
  by DEC OSF/1. DEC purchased by Compaq
     Unix is Made Up of

• Running Programs
   User owned
   System owned
• Regular Files:
   – Data
   – Executables <-- usually start a process
• Directory Files
   – Contain other files and directories
• Special Files
       Our View of the World
             as Users

                Your Shell
                A shell is a process
                that acts as an
                interface to the OS. It
Unix   Shell    allows the user to run
                programs individually
                and together to
                accomplish a task.
                         Simple Unix
                      Directory Structure


                usr      etc          home            bin        var ...

       local bin ... class             grad          ugrad ...

Fred Kuhns ()            mmscott jpeckhar...
                         CS523S: Operating Systems
       Your First Command
Man(manual) -- Documentation is your friend

• Syntax: man topic
• man provides online documentation on nearly every
  standard command and configuration file.
• Optional Syntax: man -k keyword
• man man for more details
         Special Directories

Home Directory
• /home/grad/jpeckhar
• ~jpeckhar
• ~
• A user generally has permission to freely manipulate
  files within this directory and its children.
• Users start with their home directory as their pwd
  when they login.
      Changing Directories

• The cd(Change Directory) command is used to
  change directories
• cd path
• Paths can be relative or absolute
• pwd reports present working directory
• cd when entered by itself sets the pwd to the
  user’s home directory.
       Other File System Utilities

• ls        Lists all files in a directory
• cp        Copies files
• mv        Moves files
• rm        Deletes files
• mkdir     Makes directories
• rmdir     Removes directories
          Basic Syntax

• ls       ls
• cp       cp source dest OR
           cp source … dir
• mv       mv source dest OR
           mv source … dir
• rm       rm file
• mkdir    mkdir new directory name
• rmdir    rmdir directory to be removed
   Using Other Commands
         Syntax: command file

• cat    Echos file contents to the screen
• grep   Searches a file for a string
• more   Echos a file a line at a time
• less   Same as more but more features
• wc     Counts the words in a file and more
• sort   Sorts the contents of a file

• Pipes connect stdout of one command
  to stdin of another comand.
• ls | less
• cat student_list | grep senior | sort
         I/O Redirection

• I/O redirection allows the user to change
  where input to a command or output from
  a command goes to/comes from.
• cat student_list > outfile
• program < infile
• program < infile > outfile
    Standard File Handles

Every Unix process automatically comes with
three file handles or descriptors.
These are:
 Standard Input (stdin)
    Keyboard
 Standard Output (stdout)
    Display
 Standard Error (stderr)
    Display (unbuff)

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