LSN 10 Linux Overview

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1 LSN 10 Linux Overview ECT362 Operating Systems Department of Engineering Technology

2 LSN 10 Linux Overview Linux Contemporary open source implementation of UNIX available for free on the Internet Introduced in 1991 by Linus Torvalds UNIX OS introduced in 1973 Small no-frills OS Kernel only contained essential functionality Source owned by AT&T Bell Labs (Lucent) 1989 released a common program interface POSIX First free form of UNIX source code

no-frills OS Kernel only contained essential functionality Source owned by AT&T Bell Labs

complete OS (just like UNIX) Common distributions Red

3 LSN 10 Linux Distribution Includes OS Wide variety of supplemental tools Linux is the kernel of an OS, not a complete OS (just like UNIX) Common distributions Red Hat Fedora Mandrake SUSE Debian Linspire (Lindows) Ubuntu

4 LSN 10 Kernel Organization Linux uses a monolithic kernel All OS functions reside in a single executable software module except device management Device management is handled by a separate collection of device drivers and interrupt handlers Linux added a container called a module to the standard UNIX kernel organization Implement extensions to the main part of the kernel Can be dynamically installed with OS running

drivers and interrupt handlers Linux added a container called a module to the standard UNIX kernel

5 LSN 10 Kernel Organization Using Linux kernel services Kernel ADT Kernel software contains no threads of execution or processes User programs must link to the kernel code to use it Use a hardware trap instruction to keep user code from running in supervisory mode Serial execution Linux is a single-threaded kernel Kernel functions can operate without concern of being interrupted

hardware trap instruction to keep user code from running in supervisory mode Serial execution

6 LSN 10 Linux Kernel Responsibilities Resource abstraction Creation of software to simplify the operations that must be applied to the hardware to cause it to function properly Device drivers The computer s components are abstracted into processes and resources Manage allocating and deallocating the system s resources to and from the processes as they execute

properly Device drivers The computer s components are abstracted into processes and

7 LSN 10 Installing Linux Distribution Complete Linux system Kernel Archive Linux kernel source code Supported Hardware

com/ Kernel Archive Linux kernel source code

8 LSN 10 Installing Linux Types of installations Server MB Does not include the graphical interface Standard desktop / workstation MB Includes graphical desktop and common utilities Developer s workstation MB Adds software development packages Complete installation GB

Includes graphical desktop and common utilities Developer s workstation

9 LSN 10 Installing Linux System setup procedure Imaging a computer Hard drive partitioning Device driver verification

10 LSN 10 Linux System Booting Dual boot systems Requires a boot manager program to select desired OS to use GRUB LILO Booting procedure i386 machines are typically designed to support Microsoft OSs Incorporate Basic I/O System (BIOS) in ROM OS loaded from boot disk Contains Master Boot Record (MBR) at first logical sector Details the disks physical layout Kernel code is started by boot loader once the OS is placed into main memory Initial process starts the idle process

in ROM OS loaded from boot disk Contains Master Boot Record (MBR) at first logical sector Details the disks physical

11 LSN 10 Linux VM Virtual Machine Isolated OS running as an application on a host OS Process VM (application virtualization) System VM (hardware virtualization) Run Linux on a virtual machine on top of another OS Oracle VirtualBox VM

virtualization) System VM (hardware virtualization) Run

12 LSN 10 Linux Users Linux user accounts root user sudo

13 LSN 10 The Linux Desktop A graphical display is optional in Linux Linux graphic display is based on the X Window System X server Program that communicates with the video card, keyboard, and mouse X client Any graphical application Window manager Special purpose graphical application Graphical libraries Collection of programming functions that X clients can use to manage the graphical environment elements

client Any graphical application Window manager Special purpose graphical application Graphical

14 LSN 10 The Linux Desktop Desktop interfaces Manage icons Manage multiple application environments (windows) Provide basic user applications KDE GNOME

15 LSN 10 The Linux Shell Provides an easy interface for user to run programs and work with files in Linux Types of shells Bourne shell (sh) Bourne Again shell (bash) C shell (csh) Korn shell (ksh) Z shell (zsh)

16 LSN 10 The Linux Shell Linux Shell Commands (only a few) cat display requested text file ps process status ls show list of files in directory pwd print working directory grep find text within a file man manual, provides in-depth information about requested command cd change to desired directory chmod change the file/directory permission

directory grep find text within a file man manual, provides in-depth information

17 LSN 10 The Linux Shell chown change owner of file/directory clear clear the screen cp copy files cmp compare two files finger get user information mount/unmount mount or unmount a file system su switch user, or become super user if user name is not given, or change the user ID top to see process information in neat format whoami about yourself

unmount a file system su switch user, or become super user if user name is not given,

18 LSN 10 The Linux Shell Shell scripts Shortcuts to perform a series of user commands Written with plain-text (do not compose in a word processor) Script format Requires a shebang at the beginning # is used for comments $_ is used to extract command line arguments $(command) is used to replace self with results from executing the command in the () Scripts must be made executable to operate

# is used for comments $_ is used to extract command line arguments $(command) is used to replace

19 LSN 10 The Linux Directory Tree

20 LSN 10 The Linux File System File system descriptors (using ls l) Directories (d) Links (l) The path PATH environment variable List of directories in the system where executable files can be found Path relativism Absolute paths start from the root directory (/) Relative paths start from current directory (pwd)

system where executable files can be found Path relativism Absolute paths

21 LSN 10 The Linux File System File system table (fstab) Lists all disks, disk partitions, and other storage devices for a given system Located in the /etc directory Comprised of several fields depicting each storage devices setup Device name mount point filesystem type mount options

22 LSN 10 /proc /proc is a virtual file system containing information about system resources Provides a mechanism for inspecting the kernel state Allows the use of read and write system calls to access the address space of another process Appears as a directory within the Linux file system

23 LSN 10 Assignment Homework HW 5 HMWRK5.pdf References Using Linux: Dalheimer, K. and Welsh, M., Running Linux, O Reilly, 5 th Edition, 2005 This is a great Linux resource Linux shell commands: Linux shell scripting:

Computer Systems and Networks. ECPE 170 Jeff Shafer University of the Pacific. Linux Basics

Computer Systems and Networks. ECPE 170 Jeff Shafer University of the Pacific. Linux Basics ECPE 170 Jeff Shafer University of the Pacific Linux Basics 2 Pre- Lab Everyone installed Linux on their computer Everyone launched the command line ( terminal ) and ran a few commands What problems were