2. What is Linux
A Unix-like Operating System
A famous open source project
Free to use, distribute, modify under a compatible licence
Produced by a large developer and user community
A combination of many projects
Cost of commercial development estimated at USD 7 billion
Companies often make money by selling:
Support
Training
Custom changes
3. How Linux can help us ?
Full operating system
Works well on a variety of hardware, including older
hardware
You can adapt it to fit your needs
Thousands of programs available
Secure by design
LAMP stack
Supports a wide range of programming languages
Scalable
4. History
1965 - Bell Labs (AT&T), GE and MIT, Project to develop a new (multiuser, multitasking) operating
system - MULTICS. (not successful)
1969 - Ken Thompson and Dennis Ritchie implemented the first UNIX system for the PDP-7.
1973 - The UNIX system was rewritten in the C programming language.
1982 - University of California, Berkeley (UCB), Developed BSD UNIX because new commercial
UNIX releases no longer included the source code.
1984 - Richard Stallman started the GNU project to create a free operating system.
1991 they created a lot of the tools but no kernel.
Professor Andrew Tanenbaum wrote the operating system MINIX from scratch to teach his students
the inner workings of a real operating system.
1991 Apr - At age 21, Linus Torvalds starts working on a new operating system inspired by MINIX.
1991 September - Linux version 0.01 is released.
6. Some Linux Flavors
http://en.wikipedia.org/wiki/List_of_Linux_distributions
7. Linux vs Windows
Linux Windows
Linux was originally built by Linus Torvalds at Firstversion of Windows – Windows 3.1
the University of Helsinki in 1991. released in 1992 by Microsoft.
Linux is a Unix-like, Kernel-based, fully Windows is a GUI based operating system
memory-protected, multitasking operating It has powerful networking capabilities, is
system multitasking, and extremely user friendly
It runs on a wide range of hardware from PCs Many beginner users find Windows easer to
to Macs. use than other operating systems
Linux has been primary used by advanced Windows is often known for a large amount of
computer users – programmers and developers loop holes
Linux is more virus proof since viruses – User Interface is well known for Windows
malicious programs either cannot be run
automatically on the Linux machine, or simply
are not capable of being executed on a 386
architecture
User Interface in latest flavors like Ubuntu is
comparatively equal
8. User Space vs Kernel Space
User Space Kernel Space
User space is the Kernel Space us
memory area where all strictly reserved for
user mode application running the kernel (OS
work and this memory background process),
can be swapped out kernel extensions and
when necessary most device drivers
User space process Linux kernel space
normally runs in its gives full access to the
own virtual memory hardware, although
space and unless some exceptions runs
explicitly requested, in user space. (The
cannot access the graphic system most
memory of other people use with Linux
processes. does not run in kernel
in contrast to that
found in Microsoft
Windows)
10. What is a process ?
Actual execution of passive collection of
instructions
Eg:
Running Adobe acrobat reader
Running word pad
Running Printer application
All the above are named as process in OS
and this can be run parallel, methodology
named as Multi-Tasking
11. What is Thread ?
In Linux threads are initiated
and executed inside a process
(process specific area)
Multiple threads can exist within
the same process and share
resource such as memory, while
different process do not share
these resource
Eg: opening multiple instance
of .pdf extension files in a adobe
acrobat reader
12. Process/Threads state Diagram
Process gets
initiated from
Creation state and
ended with
terminated state,
depending on the
logic of program
other states are
valid
13. Boot Flow diagram
GRUB ( Grand Unified
Bootloader) is Multi-boot
boot loader
A Master Boot Record is a
512 bye boot sector that
is the first sector of a
partitioned data storage
such as hard disk
Root filesystem is the file
system that is contained
on the same partition on
which the root directory is
located.
19. Open Community Links
Linux kernel availability
http://www.kernel.org/
http://www.linux.org/
Linux Drivers
http://www.linux-drivers.org/
Grub
http://www.gnu.org/software/grub/index.html
File System
http://www.busybox.net/
Google will be your best friend
20. This Document Release date
S.No Author Release Description
Version/Date
1 Suresh v0.1 / 08 Dec 2010 Initial Version
Kalidasan
