Operating Systems 1


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Operating Systems 1

  1. 1. CI1131 ICT1 Lecture Introduction to UNIX & Linux
  2. 2. UNIX & the “ *NIX” family <ul><li>UNIX developed at AT&T Bell Labs, 1969 </li></ul><ul><li>3 levels of the UNIX system: kernel, shell, and tools and applications </li></ul><ul><li>multitasking, multi-user, portable, vast suite of tools and applications, .... stable! </li></ul><ul><li>has spawned 100+ *NIXes (incl. Solaris, FreeBSD, NeXTSTEP, Mac OS X, and Linux) </li></ul>
  3. 3. UNIX <ul><li>The kernel </li></ul><ul><ul><li>the core of the operating system, the kernel controls the hardware and turns part of the system on and off at the programer's command. E.g. if you ask the computer to list (ls) 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. </li></ul></ul>
  4. 4. UNIX <ul><li>The shell </li></ul><ul><ul><li>There are several kinds of shell, most notably the command driven Bourne Shell, C Shell, Korn shell, and BASH ( B ourne A gain SH ell), and menu-driven shells (Midnight Commander, vsh, lash) that make it easier for beginners to use. Whatever shell is used, its purpose remains the same -- to act as an interpreter between the user and the computer. </li></ul></ul>
  5. 5. UNIX <ul><li>Tools and applications </li></ul><ul><ul><li>There are hundreds of tools available to UNIX users, although some have been written by third party vendors for specific applications. Typically, tools are grouped into categories for certain functions, such as word processing, business applications, or programming. (Try typing, for example, apropos editor at the command prompt.) </li></ul></ul>
  6. 6. Some UNIX references <ul><li>The Creation of the UNIX Operating System </li></ul><ul><li>http://www.bell-labs.com/history/unix/ </li></ul><ul><li>The Single UNIX Specification </li></ul><ul><li>http://www.unix.org/what_is_unix/ </li></ul><ul><li>Unix History </li></ul><ul><li>http://www.levenez.com/unix/ </li></ul><ul><li>A Brief History of UNIX </li></ul><ul><li>http://www.uwsg.iu.edu/usail/external/recommended/unixhx.html </li></ul>
  7. 7. LINUX <ul><li>Project begun by Finnish student Linus Torvalds in 1991 </li></ul><ul><li>Strictly, Linux is just the kernel – the operating system itself is GNU </li></ul><ul><li>Many popular *NIX alternatives also using GNU OS: </li></ul><ul><ul><li>FreeBSD, BeOS, OpenBSD, NetBSD, ... </li></ul></ul>
  8. 8. Linux is free <ul><li>Linux mimics the form and function of a UNIX system, but (important!) is not derived from licensed source code , hence 'free' </li></ul><ul><li>No one “owns” Linux: it it not a company or an organisation </li></ul><ul><ul><li>Anyone is free to create a new “distribution” </li></ul></ul><ul><ul><li>Examples: Fedora, Debian, Mandriva, SuSE, Ubuntu, Gentoo, Centos, BLAG, Knoppix, Mepis, Sabayon, dyne:bolic, ... and around 100 or so others! See, e.g. </li></ul></ul><ul><li>http://distro.ibiblio.org/pub/linux/distributions/ </li></ul>
  9. 9. Linux directory structure [1] <ul><li>/ </li></ul><ul><ul><li>root directory of the entire system </li></ul></ul><ul><li>/bin </li></ul><ul><ul><li>holds system executables ('programs') </li></ul></ul><ul><li>/sbin </li></ul><ul><ul><li>holds system executables essential for starting up the system </li></ul></ul><ul><li>/boot </li></ul><ul><ul><li>holds the files (including the kernel) needed during the booting process </li></ul></ul>
  10. 10. Linux directory structure [2] <ul><li>/dev </li></ul><ul><ul><li>special directory that holds information regarding peripherals ('devices') </li></ul></ul><ul><li>/home </li></ul><ul><ul><li>the home directories for all users except root </li></ul></ul><ul><li>/lib </li></ul><ul><ul><li>system binary libraries, shared libraries and kernel module </li></ul></ul><ul><li>/opt </li></ul><ul><ul><li>where optional applications might go </li></ul></ul>
  11. 11. Linux directory structure [3] <ul><li>/root </li></ul><ul><ul><li>home directory for super user </li></ul></ul><ul><li>/tmp </li></ul><ul><ul><li>where temporary files are stored, usually emptied on system restart </li></ul></ul><ul><li>/var </li></ul><ul><ul><li>where variable system files go (system logging, file locks, printer spooling, mail spooling, web server, etc) </li></ul></ul><ul><li>/etc </li></ul><ul><ul><li>holds almost all configuration files </li></ul></ul>
  12. 12. Linux directory structure [4] <ul><li>/mnt </li></ul><ul><ul><li>'mount point' for temporarily mounting other media, e.g. CD-ROM, USB drive, iPod, and other file systems </li></ul></ul><ul><li>/usr </li></ul><ul><ul><li>holds application programs, source code, additional libraries, wallpapers, icons, etc </li></ul></ul><ul><li>/usr/bin </li></ul><ul><ul><li>contains binary executables </li></ul></ul>
  13. 13. LINUX: the X environment <ul><li>Beyond the shell ... users are 'cushioned' from the shell by a GUI: </li></ul><ul><ul><ul><li>X server: handles communication between the hardware (in particular the graphic card) and software (the X programs) ... and nothing else </li></ul></ul></ul><ul><ul><ul><li>X client: displays graphics and graphical frontends </li></ul></ul></ul><ul><ul><ul><li>'windowmanager' (FVWM, Enlightenment, IceWM, ...): basic window functionality (menu, max, min, close, ...) </li></ul></ul></ul><ul><ul><ul><li>'desktop environment' (KDE, Gnome, ...): clickable icons, taskbar, general “look'n'feel”. Desktops also usually come bundled with applications. </li></ul></ul></ul>
  14. 14. The KDE desktop
  15. 15. KDE with Compiz
  16. 16. KDE with Kate
  17. 17. Some Linux references <ul><li>Linux Online (the place to start) </li></ul><ul><li>http://www.linux.org </li></ul><ul><li>History of Linux </li></ul><ul><li>https://netfiles.uiuc.edu/rhasan/linux/ </li></ul><ul><li>The GNU Operating System </li></ul><ul><li>http://www.gnu.org </li></ul><ul><li>The Free Software Foundation </li></ul><ul><li>http://www.fsf.org </li></ul>