Operating Systems: Types and Linux OS

• The Operating System (OS) manages all of the software and hardware on a computer.
• The shell is the outermost layer of the OS, managing interaction between the user and the OS by prompting, interpreting input, and handling output.

Types of Operating Systems

• Multitasking OS: also known as a time-sharing OS, gives each task time to work efficiently.
• Example: UNIX
• Network Operating Systems: run on a server and manage all networking functions.
• Example: Microsoft Windows Server 2008, Linux
• Mobile OS: an operating system for smartphones, tablets and PDAs.

Linux Operating System

• Linux is an open-source, freely distributable, cross-platform OS based on UNIX that can be installed on PCs.
• Offers freedom to run the program for any purpose
• Offers freedom to study and change the program, with access to the underlying source code
• Offers freedom to share copies to help neighbors
• Offers freedom to distribute copies of modified versions.

Creator of Lixus

• Linus Benedict Torvalds: a Finnish-American software engineer, is the creator and principal developer of the Linux kernel .
• The Linux kernel is the kernel for Linux operating systems (distributions) and other operating systems such as Android and Chrome OS.
• Born on December 28, 1969

History of Linux

• In, 1991 Linus Torvalds began Linux as a personal project to create a new free operating system Kernel.

Linux Distributions

• Fedora (Red Hat)
• OpenSUSE (SUSE)
• Ubuntu (Canonical Ltd.)
• Debian
• Slackware
• Gentoo
• Arch Linux
• CentOS

Debian-Based Distributions

• MX Linux
• Linux Mint
• Ubuntu
• Deepin
• Antix
• PureOS
• Kali Linux
• Parrot OS
• Devuan
• Knoppix
• AV linux

Redhat Based Distributions

• Rocky Linux
• Alma Linux
• CentOS

Locate and help resources

• Man pages: an abbreviation of the manual or man page
• Info Pages: are no longer provided with manual pages- using info pages instead

Parts of a Man Page

• NAME: short Command description
• SYNOPSIS: Description of the syntax
• DESCRIPTION: Detailed command description
• OPTION: All available options descriptions
• COMMANDS: Instructions to be given to the program during running.
• FILES: the way files connected to the command.
• SEE ALSO: Hints on related commands.
• DIAGNOSTICS: Error messages for the program.
• EXAMPLES: commands of calling up a command.
• BUGS: Bugs and problems with the command

GUI and CLI Demonstration

• Graphical User interface (GUI) permits users to use the graphics to interact with an operating system.
• Command Line Interface (CLI): permits users to write commands associate degree exceedingly in terminal or console window to interact with an operating system.

change directories and list contents

• cd: Change directory
• ls:list directory content
• pwd: Print working directory.

create and view files

• touch: Create an empty file/Change file time stamp.
• cat: display file contents
• less: display file contents one page at a time
• head: display first 10 lines of a file
• tail: display last 10 lines of a file

work with files and directories

• mv: Move files and directories
• cp: Copy files and directories
• mkdir: Create directories
• rm: Delete files and directories
• rmdir: Delete empty directories
• rm-i will ask before deleting each.

Command options

• Consider using rm -I instead, which will only ask once only if you deleting three or more files.

• rm -r will recursively delete a directory and all its contents (rmdir will only delete empty directories.)

• w: displays the log-in session information of the user.

• whoami: display the current user being used.

• pwd: print working directory(current location.)

• last: used to display a of users who have previously logged into the system.

• lastb: used to display information pertaining to failed login attempts. disk free

• sudo: Command utility for Unix such as Linux and macOS.

Components of Operating system

• Kernel: the core component of an operating system which acts as interface between applications, and the data is processed at the hardware level.

Linux Directories

• Essential Binaries for Use by All Users (/bin)
• /bin/bash: The bash shell
• /bin/cat: Displaying files
• /bin/cp: Copying files
• /bin/dd: Copying files byte-wise
• /bin/gzip: Compressing files
• /bin/mount: Mounting file systems
• /bin/rm: Deleting files
• /bin/vi: vi editor

The Hierarchical Structure of the File System

• Hierarchical structure of the file system may be depicted as an inverted tree.
• The separation character between individual directory names is a slash "/".
• Relative Path: Starts from the current directory.
• Absolute Path: Starts from the root of the entire file system tree, always beginning with /"

Root Directory ("/")

• Highest layer of the file system tree
• Partition located is the first one mounted upon system boot up
• /bin,/dev,/etc,/lib,and/sbin directories always have to be on the same partition as root.

Device Files (/dev)

• Each hardware component in the system is represented as a file in /dev directory.
• Hardware components are addressed via these files by writing or reading from one of these files.
• Two kinds of device files are included: block,character-oriented

Other Partitions (/data)

• If YaST finds other (non-Windows) partitions or another hard disk during the installation.
• Creating the mount points for each partitions labeled/data/data2,and/datax.

Boot Directory(/boot)

• Contains static files of the boot loader (GRUB)
• Contains the kernel(vmlinuz).
• Also contains backed up information for the Master Boot Record (MBR) and system map files.

Important Device Files

• /dev/console OR /dev/tty1: Terminals Device File
• /dev/ttyS0.../dev/ttyS*: Serial Ports Device File
• /dev/Ip0.../dev/1p*: Parallel Ports Device File
• /dev/fd.../dev/fd*: Floppy disk drives Device File
• /dev/hda.../dev/hd*: IDE hard drives Device File
• /dev/hd*: IDE CD-ROM drives Device File
• /dev/sda.../dev/sd*: SCSI hard drives Device File
• /dev/sda.../dev/sd*: SATA hard drives Device File
• /dev/scd0.../dev/scd*: SCSI CD-ROM drives Device File

Application Directory (/opt)

• The application is the application's name.
• Installed programs can store their static files in this directory
• First, create a directory with application's name
• Files are stored in its address
• "/opt/gnome": For GNOME example
• "/opt/kde3": For KDE

Configuration Files (/etc)

• /etc/SuSE-release
• /etc/passwd
• /etc/inittab
• /etc/shadow
• /etc/init.d/*
• /etc/group
• /etc/modprobe.conf
• /etc/cups/*
• /etc/DIR_COLORS
• /etc/hosts
• /etc/X11/xorg.conf
• /etc/motd
• /etc/fstab
• /etc/issue /etc/profile

User Directories (/home)

• .profile : login script pf the user
• bashrc: configuration file for bash
• .bash_history: Command list previously run in bash

root's Home Directory

• Administrator home directory
• Not located in /Home
• Should be on the same partition as root("/") directory

System Binaries (/sbin)

• /sbin/SuSEconfig
• /sbin/fsck*
• /sbin/conf.d/*
• /sbin/init
• /sbin/yast
• /sbin/mkfs*
• /sbin/fdisk
• /sbin/shutdown

Libraries (/lib)

• Contain libraries that are used for directories/bin and /sbin programs.
• Kernel modules are located in /lib/modules directories.
• May also be found in /usr the directory additional libraries

Data Directories for Services (/srv)

• Contains sub directories designed for various containing service data.
• /srv/www/: Apache web example
• /srv/ftp/ : FTP server

Temporary Area(/tmp)

• Various programs create temporary files and stored in/tmp will be deleted.

Mount Point for Temporarily Mounted File Systems(/mnt)

• The system standard directory the file integration is for /mnt.

• Should be only used for temporary purposes.

• Mount the ( /dev/hda/.7) partition to /mnt to command command, and unmount(/mnt) partition.

Locally-available File Systems

• /bin
• /boot
• /dev
• /etc
• /lib
• /sbin

File System Hierarchy Standard

• Describes file system standard structure
• Defines two layered of hierarchy
• The top later directories
• The second directories under /usr and /var

Structure of the File System

• Depicted as an inverted tree
• Name separation
• Relative/Absolute Path

The Hierarchy Below /usr

• Unix Specific Resources OR Unix System
• /usr/X11R6/: Files for the X Window System
• /usr/bin/: Almost all executable programs
• /usr/lib/: Libraries
• /usr/local/: Locally-installed programs
• /usr/The manual pages Documents
• /usr/sbin/: Programs for system administration
• /Documentation
• /usr/Documents: The manual pages
• /usr/src/: Source files of all programs and the kernel
• /usr/share/man/:The manual pages

Variable Files (/var)

###DIRECTORY

• /var/lib/: Volume libraries
• /var/log/: For most service Log files
• /var/run/:Running Files with information
• /var/spool/:Directory for queues
• /var/lock/lock: Multiple protection device from using locks
• Windows Partitions (/windows)
• MS finds any directories automatically /windows with YaST
• /windows labeled the directories these subdirectories
• Process Files (/proc)
• /proc/sys/*
• /proc/version

System Information Directory (/sys) structure on

• various buses
• drivers
• hardware devices
• active devices
• /etc(configuration)
• /media
• /proc

FILE SYSTEM HEIRARCHY

• /bin (Binary): Contains command such as command,Is, cp, mv, and cat.
• /sbin(System Binary): task system Contains binaries administrative fdisk,shutdown, and iptables
• /var (Variable): Stores variable data in the following
• /root(Root Home): The root home directory.
• /dev (Devices): Contains hardware and peripherals device files.
• /etc (Configuration): System wide configuration files. /media: Removable media mounting being Used files.

(/proc). File systems include:

• Temporary- /tmp.
• Service -/svr.
• Boot . /boot

Explore the role of operating systems in managing computer software and hardware. Learn about multitasking, network, and mobile OS types. Discover the features and benefits of the Linux operating system.