Introducing linux: a short expedition to the debian environment

Introducing Linux
Md. Zahid Hossain Shoeb
Independent University, Bangladesh (IUB)
a short expedition to the environment
Deputy Librarian (Systems)
BALID Training Programme on Koha
Date: 3-7 September, 2013
Venue: North South University, Dhaka

Overview
• Operating system
• Road to Linux
• GNU, Free Software
movement
• Popularity of Linux
• Linux Overview
• Why should use Linux
• About Debian
• Debian Features
• Package, Repository
• GUI / CLI interface
• Tools under Menu
panel
• Basic commands
BALID Training Programme on Koha 2

Operating Systems
• Software
– Collection of instructions that control the tasks a
computer performs
– Can be changed without disassembling the
computer and rewiring
• Application
– Software program that provides service for
computer user
– Cannot act without “permission” from
operating system

Operating Systems (continued)
• Operating system (OS)
– Software that helps other programs control
computer hardware and interact with users
– All computers need an OS
– Popular OSes include Windows, Linux, Mac OSX

Operating System Functions
• Initialize computer hardware
• Allocate system resources to programs
• Keep track of multiple programs running at
same time
• Provide organized method for all programs to
use system devices

Before Linux
• In 80’s, Microsoft’s DOS was the dominated OS
for PC
• Apple MAC was better, but expensive
• UNIX was much better, but much, much more
expensive. Only for minicomputer for
commercial applications
• People was looking for a UNIX based system,
which is cheaper and can run on PC
• Both DOS, MAC and UNIX were proprietary, i.e.,
the source code of their kernel is protected
• No modification is possible without paying high
license fees

Road to Linux
• Inspired by the UNIX OS, the Linux kernel was
developed as a clone of UNIX
• GNU was started in 1984 with a mission to
develop a free UNIX-like OS
• Linux was the best fit as the kernel for the GNU
Project
• Linux kernel was passed onto many interested
developers throughout the Internet
• Linux today is a result of efforts of Linus Torvalds
and thousands of individuals, in 1991

Linux arrived
• Linux is basically a kernel, it was combined with
the various software and compilers from GNU
Project to form an OS, called GNU/Linux
• Linux is a full-fledged OS available in the form of
various Linux Distributions
• RedHat, Fedora, SuSE, Ubuntu, Debian are
examples of Linux distros
• Linux is supported by big names as IBM, Google,
Sun, Novell, Oracle, HP, Dell, and many more

Linux arrived (continued)
• Linux development method
– Person identifies need and begins writing program
– Developer announces project on Internet
– Others respond and work on different parts of project
– Person leading project releases software
– People download source code and try program; send
back information about problems
– Developers fix bugs
• Forking
– Creating new project based on existing source code

GNU
• Stands for GNUs Not Unix. GNU General Public License.
GNU - GPL – Copyleft
• Free software, as defined by the FSF (Free Software
Foundation), is a "matter of liberty, not price."
• Terms for using Linux
– You can modify / copy / redistribute the source code at no
cost provided you do so under the GPL
– If you get source under the GPL, any changes /
improvements / spin offs you make to it are also under GPL
– You must always distribute source code + GPL of programs
that you develop with the help of GPL software online.

Motivating Free Software Developers
• Why would so many people devote so much
effort to something without expecting any
reward?
– Fills developer’s specific technical need
– Respect of like-minded professionals
– Sense of contribution and community
– Valuable boost to developer’s resume

Why the popularity of Linux?
• Hardware
– Cost of hardware always decreases.
– Usage of a hardware required the device drivers to
be available.
– Writing new drivers for Linux is the easiest
solution. (For unavailable devices)
– Once the drivers were ready, they were
incorporated into the main source so as to give
everybody access to it!

• Cost of developing tools
– Hardware developers rather than developing a
complete OS for a processor, could simply port
Linux to that platform.
– Then everything that works in Linux will work
seamlessly reducing cost to a fraction.
– Driver Maintenance / Bug Fixes and improvements
contributions from the FOSS community.

• Software Developers
– A consistent software environments that is
completely machine independent.
– Every system will have a GNU toolchain to compile
code for the resident platform!
– If source distribution is given, the software can be
distributed in C without worrying about hardware
support.

Language of Linux
• Linux was written completely in C and ASM.
• UNIX (1969) was written in PDP-7 Assembly.
– This version of UNIX was unportable to new
hardware.
• Thomson developed B as a machine
independent language to make UNIX portable.
• Dennis Ritchie rewrote UNIX in C, a language
he developed from B and concepts from other
languages.

Linux : More than an OS
• Like as OS Linux supports
– Memory Management
– Device management
– Task Scheduling
– User Management
– And more…
• But it also comes with a set of tools and
utilities that make life easier for the
user/developers

Overview of Linux
• Kernel Interface
• Multi-user , Multiprocessing, MultiTasking,
Multithreading
• Hierarchical Filesystem
• A Shell Interpreter for the OS
• Device independent I/O
• Inter Process Communication
• Security
• GUI
• Software Development

Kernel Interface
• Kernel is the Heart of the linux OS.
• Handles all the background OS tasks.
– Divides system resources
– Manages memory
– Gives access to devices
• Kernel abstracts the hardware from the rest of
the processes.
• Different Hardware need different setup and
compiled kernels, and all other functionality will
be unchanged.

Linux Kernel Diagram

MultiTasking
• Linux was always a fully protected multitasking
OS.
• Jobs can be run in background, and owned by
different users – on the same processor.
• Linux manages resource between active
processes / background processors and keeps in
sync seamlessly.
• capable of supporting and utilizing more than
one computer processor.
• allow different parts of a software program to run
concurrently.

Hierarchical FileSystem
• Files are kept in directories
• Directories can hold other directories.
• FHS – Filesystem Hierarchy Standard defines
the rules for where certain files will always be
kept.
• The “root” of the Linux FS is always ‘/’
• Files & directories can be owned by users to
enforce security privileges.

Hierarchical File System

Hierarchical File System
Directories
User home
directories
Data files (example)
root– Data files are
stored in
directories
(folders)
– Directories
may be
nested as
deep as
needed
/
etc
file a file b
passwd inittab
koha dspace opensrf
usrhome

BASH – the Linux Shell system
• Bourne Again Shell is s command processor
• It acts as an interface between the user and
the operating system
• Commands / applications can be given to this
interpreter which can then make the
operating system do various tasks
• Commands can be stored in shell scripts for
ease of access

Device independent I/O
• All physical devices – monitor, mouse,
keyboard printer appear as files in the Linux
file system that are manipulated by the kernel.
• This means that if a program is written to
manipulate this file, then the kernel will take it
to mean an action on the physical I/O device.
• This allows for a standard API for I/O in all
Linux systems.

Linux User Interface
• Can be controlled through command Line
Interface(CLI) or Graphical User Interface (GUI)
• GUI run through Desktop Environments (DE)
• KDE, GNOME, Xfce, E17 are popular Des
• The GUI interface is easy-to-use and much like
that of Windows and Mac OSX
• The CLI is similar to that of UNIX/BSD

Programming in Linux
• Modern languages are cross-platform, like
Python, Ruby, Perl, Java
• Most Linux distros support these languages and
have their runtimes pre-installed
• GTK+ and Qt are widely used to design
applications for Linux
• IDEs like NetBeans, Anjuta, KDevelop,
MonoDevelop, Eclipse are available for Linux too

Linux on the Desktop
• Linux is desktop computer ready
• Large number of distros targeted at Desktop
users are available
• Linux desktop distros come with many commonly
used pre-installed softwares
• The modern Linux interface is user-friendly and
makes the interaction with computer easy

Linux on Servers and Supercomputers
• Linux is the most used OS on servers
• 6 out of 10 reliable web hosting companies use
Linux
• Linux is the cornerstone of the LAMP server-
software combination (Linux, Apache, MySQL,
Perl/PHP/Python) which has achieved popularity
among developers
• Out of top 500 supercomputers, Linux is deployed
on 427 of them

Why should you use Linux?
• Linux systems are extremely stable
• Linux is Free
• No threat of viruses
• Linux comes with most of the required software pre-installed
• Update all your software with minimum fuss
• Linux never gets slow
• Linux does not need defragmentation
• Linux can even run on oldest hardware
• Adding more software is a matter of a few clicks
• Most Windows-only apps have their either their native
version or alternatives for Linux
• With Linux, you get the highest degree of possible
customizability

Debian: about
• Debian is an operating system composed of free
software mostly carrying the GNU General Public
License
• Its focus of different kernels makes it appeal to
different titles, such as Debian GNU/Linux and Debian
GNU/kFreeBSD
• Debian GNU/Linux is one of the most popular Linux
distributions for personal and Internet server machines
• Debian is seen as a solid Linux, and as a consequence
has been used as a base for other Linux distributions
• More than 20 awards have been awarded throughout
Debian's lifetime including Best Linux Distribution

Debian: Features
• Beside Linux and kFreeBSD, Debian has more
two kernels in development, GNU Hurd and
NetBSD
• The kernel is offered for Intel/AMD 32-bit and
64-bit architecture machines
• Debian is still primarily known as a Linux
distribution with access to online repositories
hosting over 37,500 software packages

Debian: Features
• Debian officially hosts free software on its
repositories but also allows non-free software to
be installed
• Debian offers 10 DVD and 69 CD images for
download and installation, but only the first
optical iso image of any of its downloadable sets
is sufficient
• Debian requires the first installable image, but
uses online repositories for additional software
• Debian offers different network installation
methods for expert users.

Debian: Environment
• Command Line Interface
• Desktop environments
– Most popular GNOME (the default), KDE Plasma
Workspaces, Xfce and LXDE
• Debian-Live
– A Debian-Live system can be booted from
removable media
– Debian-Live allows a user to try a Debian desktop
without actually installing

Debian: Default GUI

Debian: Logging into CLI
• To go to the command prompt from GUI, press
Alt+Ctrl+F1
• To return to the GUI, press
Alt+Ctrl+F7

Debian: The Menu Panel
• Applications
– The Applications menu contains a variety of icons that start
software applications. It is similar to the Microsoft Windows
Start menu
• Places
– The Places menu contains a customizable list of directories like,
Home, Desktop, Documents, Downloads, Picture, Search,
Recent documents, Computer places etc.
• System
– The System menu contains a variety of Systems Administration
related items like, Software Sources, Update, Package Manager,
Printing, Network, Services etc. along with Logout and
Shutdown option

Debian: Menu items

Debian: Package and Rpository
• Package management
– Debian's official standard for administering
packages on its system is the APT (Advanced
Package Management) toolset
– An APT tool allows administration of an installed
Debian system for retrieving and resolving
package dependencies from online repositories
– APT tools depend on verifying what is installed in
the dpkg database in order to determine missing
packages for requested installs.

Debian: Package and Rpository (cont..)
• dpkg database
– dpkg is the storage information center of installed
package
– database is located at /var/lib/dpkg/available
– contains the list of "installed" software on the
current system

• Package management
– In TUI apt-get and apt-cache are command tools
of the standard APT-class tool set apt package,
aptitude command supports better search on
package metadata
– In GUI gdebi is an APT combines the functionality
of the dpkg tool and APT package resolving with
online repositories

• Repositories – Official, unofficial and third-
party
– Official: stable (current), old stable (prior
release), backports (more recent), testing (next
major release), unstable (under development),
snapshot (older version), experimental (temporary
stage for developers)
– Unofficial: non-free, contrib
– Third-party: not part of Debian Project

Debian: Release timeline

Debian: Basic commands
• Basic Linux Commands
– File Handling
– Text Processing
– System Administration
– Process Management
– Archival
– Network
– File Systems
– Advanced Commands

Debian: Basic commands (cont..)
• File Handling commands
mkdir – make directories
• Usage: mkdir [OPTION] DIRECTORY...
• Example: mkdir zahid
ls – list directory contents
• Usage: ls [OPTION]... [FILE]...
• Example: ls, ls -l, ls zahid
cd – changes directories
• Usage: cd [DIRECTORY]
• Example: cd zahid

• File Handling(contd...)
pwd -print name of current working directory
• Usage: pwd
vim – Vi Improved, a programmers text editor
• Usage: vim [OPTION] [file]...
• Example: vim file1.txt

cp – copy files and directories
• Usage: cp [OPTION]... SOURCE DEST
• Example: cp sample.txt sample_copy.txt
cp sample_copy.txt target_dir
mv – move (rename) files
• Usage: mv [OPTION]... SOURCE DEST
• Example: mv source.txt target_dir
mv old.txt new.txt

rm -remove files or directories
• Usage: rm [OPTION]... FILE...
• Example: rm file1.txt , rm rf
find – search for files in a directory hierarchy
• Usage: find [OPTION] [path] [pattern]
• Example: find file1.txt, find name
history – prints recently used commands
• Usage: history

• Text Processing
cat – concatenate files and print on the standard
output
• Usage: cat [OPTION] [FILE]...
• Example: cat file1.txt file2.txt
cat -n file1.txt
echo – display a line of text
• Usage: echo [OPTION] [string] ...
• Example: echo I love Debian
echo $

• Text Processing(contd...)
grep - print lines matching a pattern
• Usage: grep [OPTION] PATTERN [FILE]...
• Example: grep I
wc - print the number of newlines, words, and
bytes in files
• Usage: wc [OPTION]... [FILE]...
• Example: wc file1.txt
wc L file1.txt

• System Administration
chmod – change file access permissions
• Usage: chmod [OPTION] [MODE] [FILE]
• Example: chmod 744 calculate.sh
chown – change file owner and group
• Usage: chown [OPTION]... OWNER[:[GROUP]] FILE...
• Example:. chown remo myfile.txt

• System Administration (contd...)
su – change user ID or become superuser
• Usage: su [OPTION] [LOGIN]
• Example: su shoeb
passwd – update a user’s authentication tokens(s)
• Usage: passwd [OPTION]
• Example: passwd
who – show who is logged on
• Usage: who [OPTION]
• Example: who , who b, who q

• Advanced Commands
reboot – reboot the system
• Usage: reboot [OPTION]
• Example: reboot
poweroff – power off the system
• Usage: poweroff [OPTION]
• Example: poweroff

Thank you

Introducing linux: a short expedition to the debian environment

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