Islamic University – Gaza
Engineering Faculty
Department of Computer Engineering
ECOM 4010: Operating Systems Lab
Lab # 1
Introduction to Linux
Eng. Eman R. Habib
September, 2013
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What is an Operating System?
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A program that manages the computer hardware. It also provides a basis for application
programs and acts as an intermediary between the computer user and the computer
hardware.
OS is a resource allocator: Manages all resources and decides between conflicting
requests for efficient and fair resource use.
OS is a control program: Controls execution of programs to prevent errors and
improper use of the computer.
The One program running at all times on the computer (usually called the kernel).
System Calls
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Programming interface to the services provided by the OS
Interface between the process and the operating system.
Typically written in a high-level language (C or C++)
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Linux
Linux is a generic term referring to Unix-like computer operating systems based on the Linux
kernel.
The development of Linux is one of the most prominent examples of free and open source
software collaboration; typically all the underlying source code can be used, freely modified,
and redistributed by anyone.
Because Linux takes the UNIX system as its inspiration, Linux and UNIX programs are very
similar. In fact, almost all programs written for UNIX can be compiled and run under Linux. Also,
many commercial applications sold for commercial versions of UNIX can run unchanged in
binary form on Linux systems.
The problem with UNIX is that is has always been expensive and taken large computers to use.
Some versions of UNIX have been available for personal computer-type hardware, but the cost
has been very prohibitive and the support by multiple vendors has been lacking. These
problems are what led to the development of Linux.
Linux was developed by "Linus Torvalds" at the University of Helsinki, with the help of UNIX
programmers from across the Internet.
Linux Architecture
The Linux architecture comprises two main sections: the kernel space and user space.
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Kernel space
The kernel space is where all of the system level processes happen. These processes are things
that affect the entire system and have to be very stable and well maintained. A problem in
kernel space can cause the system to crash. The main resident in kernel space is, of course, the
kernel. The kernel is the piece of software that manages memory allocation for processes and
divides up the CPU’s time appropriately. The kernel also contains the drivers for the hardware
devices installed in the system. The kernel is the core of the Linux operating system.
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User space
The user space manages the user processes run by people working on the system. User
processes are things such as your e-mail client, Web browser, or word processor. These
processes work with the kernel to handle low level functions such as printing to the screen or
talking to storage hardware. But, since these functions are not handled in kernel space, a
corrupted user application will not bring the entire system down.
Tip: Kernel space and user space provide an important separation. Drivers and
other things that affect system stability run in kernel space.
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Directory Structure
File system: The way the files of an operating system are organized on the disk.
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All the files are grouped together in the directory structure. The file-system is arranged
in a hierarchical structure, like an inverted tree. The top of the hierarchy is traditionally
called root (written as a slash /).
Linux sorts directories descending from the root directory according to their importance
to the boot process.
File systems from other hard drive partitions mount to directories beneath the root
directory, providing access to a single directory structure.
The File system hierarchy standard (FHS) governs the unified file system for Linux by
defining a standard set of directories, sub-directories and files.
Linux is case sensitive operating system.
Directory
/
Description
The root directory, all directories are below the / (root directory)
of the system.
/bin
Contains binary commands available to all users.
/boot
Contains kernel and boot loader files.
/dev
Contains device files.
/etc
Contains system configuration files.
/home
Contains by default the user home directories.
/lib
Contains shared programs libraries and kernel modules.
/root
Home directory for the root user.
/media
Mount point for removable media.
/mnt
Mount point for mounting a file system temporarily.
/opt
Add-on application software packages.
/sbin
Contains system binary commands.
/proc
Contains information about system state and processes.
/srv
Contains the files for services like FTP and Web servers.
/tmp
Contains temporary files.
/usr
Contains system commands and utilities.
/var
Contains data files that are changed constantly.
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Linux Distributions
Linux is actually just a kernel, so to create a complete Linux system you have to install the
source code of kernel and many other freely distributed software programs.
Usually distributions are put on CD that contains the kernel and programming tools and
utilities.
These distributions usually come with a setup program on CD to install a Linux system, they
have the same kernel but with different interfaces.
 Some Linux distributions :
 Ubuntu
 Slackware
 SuSE
 Debain
 RedHat
 Fedora
 Turbo Linux
Ubuntu
Canonical started sending out free compact discs with Ubuntu Linux in 2004 and quickly
became popular for home users (many switching from Microsoft Windows).
Canonical wants Ubuntu to be an easy to use graphical Linux desktop without need to ever see
a command line. Of course they also want to make a profit by selling support for Ubuntu.
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Download Ubuntu
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Go to the Official Ubuntu Download Page .
Choose Ubuntu 13.04, you can choose 32 bit or 64 bit then Click 'Ubuntu 13.04'.
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Click 'Not now, take me to the download ›'.
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Your download should start now.
After finishing download, you have the ISO image of Ubuntu.
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To run Ubuntu from a USB stick, the first thing you need to do is insert a USB stick with
at least 2GB of free space into your PC. The easiest way to put Ubuntu onto your stick is
to use the USB installer provided at pendrivelinux.com. You’ll need to download and
install it as follow:
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Click 'I Agree'.
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Select Ubuntu Desktop Edition from the dropdown list.
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Click 'Browse' and open the downloaded ISO file.
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Choose the USB drive and click 'Create'.
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Click ‘Yes’.
Start installing Ubuntu on USB drive.
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Installation complete, click ‘close’.
Install Ubuntu 13.04:
Most newer computers can start up from a USB stick. You should see a welcome screen
prompting you to choose your language and giving you the option to either install Ubuntu or try
it from the USB as follow:
Choose ‘Install Ubuntu’.
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If your computer does not automatically do this, you might need to change the device from
which the computer starts up to the USB. You can usually do this by watching for a message
appearing before Windows starts. You should be invited to change the boot device. Once
you’ve selected that option, follow the instructions on screen.
Tip: You might be able to press ‘F12’ or ‘Escape’ while your computer is starting
up to change your boot device order.
Depending on your computer and how your USB key was formatted, you should see an entry
for ‘removable drive’ or ‘USB media’. Move this to the top of the list to force the computer to
start from USB rather than the hard disk. Save your changes and continue.
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Prepare to install Ubuntu
It’s recommended to plug your computer into a power source.
You should also make sure you have enough space on your computer to install Ubuntu.
Select Download updates while installing and Install this third-party software now.
You should also stay connected to the internet so you can get the latest updates while you
install Ubuntu.
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Set up wireless
If you are not connected to the internet, you will be asked to select a wireless network, if
available.
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Allocate drive space
Choose Install Ubuntu alongside another operating system.
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Begin the installation
Ubuntu needs about 4.5 GB to install, so add a few extra GB to allow for your files. The
installation process will begin when you click the Install Now button.
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Select your location
If you are connected to the internet, this should be done automatically. Check your location is
correct and click ’continue’ to proceed.
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Select your preferred keyboard layout
Click on the language option you need.
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Enter your login and password details
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Learn more about Ubuntu while the system installs…
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That’s it.
All that’s left is to restart your computer and start enjoying Ubuntu!
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Another way to install Ubuntu:
If you have any problem in installing Ubuntu from USB drive, you can try Windows installer,
which will install and uninstall Ubuntu in the same way as any other Windows application. It’s
simpler and completely safe.
Once the Windows installer has been downloaded, you need to open it to install Ubuntu.
To install Ubuntu, all you need to do is choose your user name and password. Do note that you
need to enter your password twice to make sure you typed it correctly.
After choosing your password, click 'Install'. The files will be downloaded and installed
automatically.
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Wait until Ubuntu is downloaded and installed. This can take quite a while - the downloaded
file size is around 500MB - but you can keep using your computer throughout.
When the installation is complete, you’ll be prompted to restart your computer. Click 'Finish' to
restart.
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After your computer restarts, choose 'Ubuntu' from the boot menu.
 Best Wishes 