Introduction to linux

Free and OpenFree and Open
Source ComputingSource Computing
Prasanth VPrasanth V
Dept. of Basic Science and Basic Engg:Dept. of Basic Science and Basic Engg:

IntroductionIntroduction
• Free software is a social movement
• Open source is development methodology
• For the free software movement, free software is an
ethical imperative, essential respect for the users
freedom.
• Open source considers issues in terms of how to
make software “better”—in a practical sense only.
Free Vs Open Source software

Introduction toIntroduction to
GNU/LinuxGNU/Linux

Before LinuxBefore 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

GNU projectGNU project
– Established in 1984 by Richard Stallman, who believes that
software should be free from restrictions against copying or
modification in order to make better and efficient computer
programs
GNU is a recursive acronym for “GNU's Not Unix”
Aim at developing a complete Unix-like operating
system which is free for copying and modification
Companies make their money by maintaining and
distributing the software, e.g. optimally packaging the
software with different tools (Redhat, Slackware,
Mandrake, SuSE, etc)
Stallman built the first free GNU C Compiler in 1991.
But still, an OS was yet to be developed

Beginning of LinuxBeginning of Linux
– A famous professor Andrew Tanenbaum developed Minix, a
simplified version of UNIX that runs on PC
– Minix is for class teaching only. No intention for commercial use
– In Sept 1991, Linus Torvalds, a second year student of Computer
Science at the University of Helsinki, developed the preliminary
kernel of Linux, known as Linux version 0.0.1

Message from Professor Andrew Tanenbaum
" I still maintain the point that designing a monolithic
kernel in 1991 is a fundamental error. Be thankful you are
not my student. You would not get a high grade for such
a design :-)“
Soon more than a hundred people joined the Linux
camp. Then thousands. Then hundreds of thousands
–It was licensed under GNU General Public License, thus
ensuring that the source codes will be free for all to copy,
study and to change.
(Andrew Tanenbaum to Linus Torvalds)

Linux TodayLinux Today
– Linux has been used for many computing platforms
– PC, Supercomputer,…
– ATMs....
– Not only character user interface but graphical user interface
is available
– Commercial vendors moved in Linux itself to provide freely
distributed code. They make their money by compiling up
various software and gathering them in a distributable format
– Red Hat, Slackware, etc

Linux - free softwareLinux - free software
• Free software, as defined by the FSF (Free Software
Foundation), is a "matter of liberty, not price." To qualify as free
software by FSF standards, you must be able to:
– Run the program for any purpose you want to, rather than be
restricted in what you can use it for.
– View the program's source code.
– Study the program's source code and modify it if you need to.
– Share the program with others.
– Improve the program and release those improvements so that
others can use them.

Linux groupsLinux groups
• http://www.linux.org/groups/

Linux DistributionsLinux Distributions
• http://www.linux.org/dist/list.html

Linux ShellLinux Shell
 Shell interprets the command and
request service from kernel
 Similar to DOS but DOS has only one
set of interface while Linux can select
different shell
– Bourne Again shell (Bash), TC shell
(Tcsh), Z shell (Zsh)
Kernel
Bash, Tcsh, Zsh
ls pwd
whoami
 Different shell has similar but different functionality
 Bash is the default for Linux
 Graphical user interface of Linux is in fact an application
program work on the shell

command to show the content
of current directory
command to show the content
of current directory with option
-al
The prompt $ shows that
bash shell is using
All LINUX commands start with the name of the
command and can be followed by options and arguments.
LINUX Command line InterfaceLINUX Command line Interface

File system-HierarchyFile system-Hierarchy

The most important subdirectories inside theThe most important subdirectories inside the
root directory are:root directory are:
• /bin : Important Linux commands available to the average
user.
• /boot : The files necessary for the system to boot. Not all
Linux distributions use this one.
• /dev : All device drivers. Device drivers are the files that
your Linux system uses to talk to your hardware. For
example, there's a file in the /dev directory for your
particular make and model of monitor, and all of your Linux
computer's communications with the monitor go through
that file.
• /etc : System configuration files.
• /home : Every user except root gets her own folder in here,
named for her login account. So, the user who logs in with
linda has the directory /home/name, where all the personal
files are kept.
• /lib : System libraries. Libraries are just bunches of
programming code that the programs on your system use
to get things done.

• /mnt : Mount points. When you temporarily load the
contents of a CD-ROM or USB drive, you typically use a
special name under /mnt. For example, many distributions
(including Fedora) come, by default, with the directory
/mnt/cdrom, which is where your CD-ROM drive's contents
are made accessible.
• /root : The root user's home directory.
• /sbin : Essential commands that are only for the system
administrator.
• /tmp : Temporary files and storage space. Don't put
anything in here that you want to keep. Most Linux
distributions (including Fedora) are set up to delete any file
that's been in this directory longer than three days.
• /usr : Programs and data that can be shared across many
systems and don't need to be changed.
• /var : Data that changes constantly (log files that contain
information about what's happening on your system, data
on its way to the printer, and so on).
The most important subdirectories inside the rootThe most important subdirectories inside the root
directory are:directory are:

Home directoryHome directory
• You can see what your home directory is called by
entering
• pwd (print current working directory)

Commands:
/ (root directory)
/root – home directory of the user root
pwd – you can see your home directory
df – to see disk space available
cd – to change to different directory or to go back to home dir
.. - move to parent directory
ls – list the contents of a directory; Options: -l (more info)
-a (displays hidden files)
-t (sort by time)
-r (oldest first)
Example: ls –ltr : display an long list of files that are sorted by time, display the oldest
ones first
Some of the basic commands you
should learn are the ones that help
you navigate the file system.

cp : copy one file to another
rm : remove a file
man : ask for the manual (or help) of a command
e.g. man cd ask for the manual of the command cd
cat : to show the content of a text file
e.g. cat abc.txt show the content of abc.txt
whoami : to show the username of the current user

Names in blue are directories, indicated by a
letter d at the beginning of the line
The concept of simple file and
directory is similar to DOS

Why I Use LinuxWhy I Use Linux

THANK YOU......THANK YOU......

Introduction to linux

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