Title: Introduction to Linux
1Introduction to Linux
2Overview
- Linux Overview
- Accessing Linux System
- Managing User and Group
- How Linux Organize Data
3Linux Overview
- What is Linux
- Features and Performance
- Linux Distributions
- Red Hat Linux Distribution
4What 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
5Features and Performance
- Technical characteristics of Linux
- Cross-platform
- Cost
- Power
- Availability
- Reliability
6Linux 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
7Red 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
8The 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
9Red 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
10Accessing 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
11Accessing 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)
12The 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
13The Display Manager GDM (cont)
- 4 pop-up menus at the Login screen
- Session
- Language
- Shutdown
- Restart
14The Display Manager GDM (cont)
- 3 choice in GDM Logout window
- Logout
- Shutdown
- Reboot
15Using Command Line Interface
- Command line interface facilities
- Logging In and Out
- Shutting Down Linux
- Starting a GUI from the Command Line
16Logging In and Out
- 2 kinds of prompts in the CLI after login
- (regular user)
- (root)
- To end session use these command
- logout, or
- exit
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18Shutting 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
19Starting a GUI from the CLI
- 2 related commands to start X Window from CLI
- startx or
- switchdesk
20Terminal 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
21Mouse 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
22Virtual 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
23Managing User and Group
- User Account
- Adding and Removing Users
- Adding and Removing Group
- The Red Hat User Manager
- User Private Groups (UPG)
24User Account
- 2 kinds of users in Linux
- Root
- Regular user
- For safety, log in as the root user only when
performing privileged operations
25Adding 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
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27Adding 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
28Adding 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
29The Red Hat User Manager
- Add, remove, and modify any user and groups
easily with the Red Hat User Manager
30User 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
31How Linux Organizes Data
- Devices
- Filesystems
- Directories and Paths
- File Permissions
32Devices
- 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
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35Filesystems
- 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
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37Directories and Paths
- Files and directories work as they do under
MS-DOS - Userss current directory after login process is
called home directory
38Directories and Paths (cont)
39Directories and Paths (cont)
- 2 kinds of pathnames
- Absolute
- Relative
- 2 special directory name
- Single dot (.) current directory
- Two dots (..) parent directory
40System 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
41Program 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
42Configuration Directories
- Configuration directories hold most Linux
configuration files - /etc common configuration files
- /etc/sysconfig more specific device service
configuration files
43Configuration 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
44The /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
45The /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
46The /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
47The /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
48The /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
49The /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
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51File 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
52File Permissions (cont)
53Permissions on GNOME
- With GNOME you can set permissions graphically
54Summary
- In this module, you have learned about
- Linux Overview
- Accessing Linux System
- Managing User and Group
- How Linux Organize Data