Introduction to Linux - PowerPoint PPT Presentation

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Introduction to Linux

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Introduction to Linux Overview Linux Overview Accessing Linux System Managing User and Group How Linux Organize Data Linux Overview What is Linux Features and ... – PowerPoint PPT presentation

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Title: Introduction to Linux


1
Introduction to Linux
2
Overview
  • Linux Overview
  • Accessing Linux System
  • Managing User and Group
  • How Linux Organize Data

3
Linux Overview
  • What is Linux
  • Features and Performance
  • Linux Distributions
  • Red Hat Linux Distribution

4
What is Linux
  • 3 major components of Linux OS
  • Kernel
  • Manage hardware devices
  • Environment
  • An Interface for the user
  • File Structure
  • Organized the way files are stored on storage
    device

5
Features and Performance
  • Technical characteristics of Linux
  • Cross-platform
  • Cost
  • Power
  • Availability
  • Reliability

6
Linux Distributions
  • Linux distribution a package that includes all
    the softwares needed to install and run Linux
  • Popular Distribution
  • Debian
  • Fedora Core
  • Red Hat Enterprise Linux

7
Red Hat Linux Distribution
  • Red Hat recognize two different types of clients
  • Business Clients
  • Experimental Clients
  • Red Hat decided to offer multiple distributions
  • "Fedora Core" is freely downloadable version of
    the distribution
  • "Red Hat Enterprise" is licensed software

8
The Fedora Core
  • Maintained and developed by an Open Source
    project (Fedora Project)
  • Release will be issued every 6 months on average
  • Designed for experimental clients

9
Red Hat Enterprise Linux
  • Focus on reliability and stability
  • Releases issued every 2 years
  • 3 Enterprise versions
  • RHE AS
  • RHE ES
  • RHE WS
  • Designed for business clients

10
Accessing Linux System
  • Accessing Your Linux System
  • The Display Manager GDM
  • Using Command Line Interface
  • Logging In and Out
  • Shutting Down Linux
  • Starting a GUI from the CLI
  • Terminal Windows and Pop Up Menu
  • Mouse Operations
  • Virtual Desktop

11
Accessing Your Linux System
  • The normal procedures are
  • Turn on computer
  • Choose Linux OS in GRUB Boot Loader
  • Enter user id and password on Login screen using
  • Command line login prompts
  • Graphical interface (default)

12
The Display Manager GDM
  • Graphical logins/logout are handled by the GNOME
    Display Manager
  • Combination key related with GDM Login window
  • CTRL-ALT-BACKSPACE
  • CTRL-ALT-F1
  • CTRL-ALT-F7

13
The Display Manager GDM (cont)
  • 4 pop-up menus at the Login screen
  • Session
  • Language
  • Shutdown
  • Restart

14
The Display Manager GDM (cont)
  • 3 choice in GDM Logout window
  • Logout
  • Shutdown
  • Reboot

15
Using Command Line Interface
  • Command line interface facilities
  • Logging In and Out
  • Shutting Down Linux
  • Starting a GUI from the Command Line

16
Logging In and Out
  • 2 kinds of prompts in the CLI after login
  • (regular user)
  • (root)
  • To end session use these command
  • logout, or
  • exit

17
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18
Shutting Down Linux
  • To turn off your computer, shut down Linux first
  • 2 ways to shut down Linux
  • halt
  • Shutdown h now
  • To force Linux to reboot
  • CTRL-ALT-DEL

19
Starting a GUI from the CLI
  • 2 related commands to start X Window from CLI
  • startx or
  • switchdesk

20
Terminal Windows and Pop Up Menu
  • X enables you to open a console session using
    Terminal window
  • To access terminal window
  • right-click on the desktop
  • select Terminal from the pop-up menu

21
Mouse Operations
  • To copy text Click and drag the mouse across the
    text to be copied
  • Text copied automatically into buffer
  • With some Windows-compatible window manager,
    press Ctrl-C
  • To paste text Click middle mouse button
  • Or, simultaneously click the left and right
    buttons

22
Virtual Desktop
  • Desktop can be scrollable larger than the size of
    the monitor using virtual desktop
  • Use Pager to move around the virtual desktop
  • Provides a thumbnail view of your virtual desktop

23
Managing User and Group
  • User Account
  • Adding and Removing Users
  • Adding and Removing Group
  • The Red Hat User Manager
  • User Private Groups (UPG)

24
User Account
  • 2 kinds of users in Linux
  • Root
  • Regular user
  • For safety, log in as the root user only when
    performing privileged operations

25
Adding and Removing Users
  • useradd
  • Enter username and user-specific values (e.g.
    group, user ID) as options on the command line
  • Get default values from /etc/login.defs
  • Copies the /etc/skel directory to users new home
    directory
  • Password is not set
  • The new user must be given a password using the
    passwd command

26
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27
Adding and Removing Users(cont.)
  • usermod
  • Takes the same options as useradd
  • Enables you to change the values for any user
    features (e.g. group, user ID, etc.)
  • userdel
  • Delete the user's login
  • With the -r option, the user's home directory
    will also be removed
  • userdel -r chris

28
Adding and Removing Group
  • groupadd
  • Used to create new groups
  • Only creates the group category. Users must be
    added individually
  • groupdel
  • Deletes a group
  • groupmod
  • Change the name of a group or its ID

29
The Red Hat User Manager
  • Add, remove, and modify any user and groups
    easily with the Red Hat User Manager

30
User Private Groups (UPG)
  • Traditionally, all users are assigned into one
    group named users
  • With UPG, a new user is assigned into a special
    group with the same name as the user
  • E.g., new user dylan is given a default group
    also called dylan

31
How Linux Organizes Data
  • Devices
  • Filesystems
  • Directories and Paths
  • File Permissions

32
Devices
  • Linux receives data from, sends data to, and
    stores data on devices
  • Generally corresponds to a hardware unit
    (keyboard, hard disk)
  • A device may have no hardware counterpart
    (pseudodevices)
  • Example
  • /dev/fd0
  • /dev/cdrom
  • /dev/hda1

33
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34
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35
Filesystems
  • Main Task of Filesystem
  • Organizes the available space
  • Provides directories and files which is a set of
    stored data
  • Every storage device has a filesystem
  • Common process for new drives
  • Format
  • Create Partition
  • Create File System
  • Examples
  • ext2, ext3, reiserfs, ntfs, vfat, nfs, smbfs

36
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37
Directories and Paths
  • Files and directories work as they do under
    MS-DOS
  • Userss current directory after login process is
    called home directory

38
Directories and Paths (cont)
39
Directories and Paths (cont)
  • 2 kinds of pathnames
  • Absolute
  • Relative
  • 2 special directory name
  • Single dot (.) current directory
  • Two dots (..) parent directory

40
System Directories
  • The / is the topmost parent directory
  • In Windows, we may call it C\
  • 3 Linux system directories
  • Program directories where applications are kept
  • Configuration directories where most
    configuration files are placed
  • System log directory that holds the system logs

41
Program Directories
  • Program directories are where installed programs
    usually store their executables
  • /bin basic user programs
  • /sbin file system management and system
    operations
  • /usr/bin program files designed for user tasks
  • /usr/sbin user-related system operation

42
Configuration Directories
  • Configuration directories hold most Linux
    configuration files
  • /etc common configuration files
  • /etc/sysconfig more specific device service
    configuration files

43
Configuration Files /etc
  • /etc holds your system, network, server, and
    application configuration files
  • Sample contents
  • fstab a list of file systems
  • grub.conf boot systems supported by GRUB

44
The /usr Directory
  • Contains subdirectories used to support users
  • Some important subdirectories
  • /usr/bin holds user-accessible applications
    utilities
  • /usr/sbin holds user-accessible administrative
    utilities
  • /usr/share directory holds architecture-independen
    t data, including documentation

45
The /mnt Directory
  • Contains the mount points for your CD-ROM, DVD,
    floppy, Zip drives, and other partitions
  • These are file systems you may be changing
    frequently
  • Example
  • /mnt/floppy
  • /mnt/cdrom

46
The /home Directory
  • Contains users home directories
  • A subdirectory with same name as user name will
    automatically be created when a user account is
    set up
  • System administrators can access any users home
    directory

47
The /var Directory
  • Contains subdirectories for tasks whose files may
    change frequently
  • Sample subdirectories
  • /var/www holds Apache web server files
  • /var/tmp holds any temporary files programs may
    need to perform a task

48
The /proc Directory
  • /proc is a special file system that is generated
    in system memory
  • Does not actually exist on any disk
  • Its files are interfaces to the kernel
  • Sample files
  • /proc/devices lists devices currently
    configured with the kernel
  • /proc/cpuinfo holds information about the
    computers CPU processor

49
The /dev Directory
  • Contains device files that represents interfaces
    to actual system devices
  • Floppy devices (/dev/fd0)
  • Hard Disk devices (/dev/hda1, /dev/sdb1)
  • CD-ROM devices (/dev/cdrom)
  • Other devices
  • To mount a file system, you have to specify its
    device name

50
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51
File Permissions
  • Restricts access to directories and files based
    on
  • The identity of the user
  • Access modes assigned to each directory and file
  • 3 kinds of permission

52
File Permissions (cont)
53
Permissions on GNOME
  • With GNOME you can set permissions graphically

54
Summary
  • In this module, you have learned about
  • Linux Overview
  • Accessing Linux System
  • Managing User and Group
  • How Linux Organize Data
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