UNIX is an operating system which was first developed in
the 1960s, and has been under constant development ever since. By operating
system, we mean the suite of programs which make the computer work. Knowledge
of UNIX is required for operations which aren't covered by a graphical program,
or for when there is no windows interface available, for example, in a telnet
session. Unix was primarily oriented towards the command
line interface, and that legacy is carried on in Linux. Thus, the graphical
user interface with its windows, icons and menus are built on top of a basic
command line interface. Furthermore, this means that the Linux file system is
structured to be easily manageable and accessible from the command line. Many
of the design conventions behind Unix also exist in Linux and are central to
understanding the basics of the system
The UNIX operating system is made up of three parts:
·
The kernel
·
The shell
·
Programs
Kernel:
The kernel of UNIX is the hub of the operating system: it
allocates time and memory to programs and handles the filestore and
communications in response to system calls.
Shell:
The shell acts as an interface between the user and the
kernel. When a user logs in, the login program checks the username and
password, and then starts another program called the shell. The shell is a
command line interpreter (CLI). It interprets the commands the user types in
and arranges for them to be carried out.
INTRODUCTION TO LINUX:
Linux is a free multitasking, multi-user network
operating system that behaves like Unix. That means Linux is not UNIX. It is a
UNIX-based operating system. It was designed specifically for the 386(x86 Intel
CPU) platform and released under GNU General Public License. Linux is technically only the kernel,
it is commonly considered to be all of the associated programs and utilities. Combined with the kernel, the utilities and often some applications comprise a commercial distribution.
it is commonly considered to be all of the associated programs and utilities. Combined with the kernel, the utilities and often some applications comprise a commercial distribution.
LINUX
DISTRIBUTIONS:
There are many Linux distributions around . Major Linux
distributions are Slackware, Debian and Red Hat. Red Hat has become commercial
but they provide resources for hackers to develop Fedora, which continue the
last Red Hat version 9. Many Linux distributions today based on these major
distributions. Beside Fedora which is based on Red Hat, there's Ubuntu which is
based on Debian. Other well-known Linux distributions are openSUSE, Mandriva,
centOS and Gentoo.
Hackers community has developed Linux for desktop as
well. Desktop operating system is an end user operating system, has graphical
user interface like Windows XP. This operating system is use to do office job,
multimedia, database job and so on. There are two excellent graphical user
interface in Linux which are, KDE and GNOME. Why is this a good news? Because other
than servers and other networking jobs, and only used by certain people, it can
be everybody's operating system as well and it's free.
Although Linux desktop is popular in Linux community and
has been used as an excellent workstation, the popularity of Linux desktop
among public going up recently is noticeable. Most Linux distributions offer
kde and/or gnome in their official releases, but the famous and excellent one
is UBUNTU. The Ubuntu team has done a very good job. The graphical installer is
fast enough which only takes less than 30 minutes of installation process. The
desktop is clean and tidy, plus many marvelous desktop wallpapers designed by
Linux community. It is a complete desktop (operating system) contains whatever
you need to do your job including office applications (word processor,
spreadsheet processor and presentation), editing photos, musics, videos,
browsing internet, email and so on.
Red Hat Linux:
For many, the name Red Hat Linux, as it is probably the
best-known Linux company in the world. Founded in 1994, Red Hat, Inc. has only
recently started showing signs of profitability, due to services rather than
the distribution itself. Yet, Red Hat Linux is a first choice for many
professionals and is likely to be a major player for a long time.
What is so special about Red Hat Linux? It is a mix of
conservative and leading-edge packages. The packages are not the most
up-to-date; once a new beta version is announced, the package versions are
frozen, except for security updates. The result is a well-tested and stable
distribution. Many servers around the world run Red Hat Linux.
One other reason for Red Hat's success is the variety of
popular services the company offers. The software packages are easy to update
via Red Hat Network, a free repository of software and valuable information. A
vast range of support services is available through the company and, while not
always cheap, you are virtually assured of an excellent support by highly
skilled support personnel. The company has even developed a certification
program to further popularise its distribution - the RHCE (Red Hat Certified
Engineer) training and examination are now available in most parts of the
world. All these factors have contributed to the fact that Red Hat is now a recognised
brand name in the IT industry.
Mandrake Linux:
MandrakeSoft is a company that has experienced an
enormous rise in popularity since its first Linux release in July 1998. They
have simply taken the Red Hat distribution, changed the default desktop to KDE
and added an easy-to-use installer, breaking the myth that Linux is hard to
install.
Mandrake Linux has since matured to become a popular
distribution among those new to Linux and among home users looking for an
alternative operating system.
SuSE Linux:
SuSE is another company with the desktop focus, not very
different from Mandrake in this respect. The distribution has received positive
reviews for its installer and configuration tools, called Yast, developed by
SuSE's own developers. The documentation, which comes with the boxed product,
has repeatedly been labelled as the most complete, thorough and usable by far. Linux Journal has
recently awarded SuSE Linux 7.3 the "Product of the Year" title. The
distribution has achieved a dominant market share in German speaking and some
Eastern European countries.
Debian
GNU/Linux:
Debian GNU/Linux is a completely non-commercial project;
perhaps the purest form of the ideals that started the free software movement.
Hundreds of volunteer developers from all over the world contribute to the
project, which is well managed and strict, assuring a quality distribution
known as Debian.
Ubuntu which is based on Debian
Linux, share the same great package management system as Debian such as dpkg,
apt, aptitude and synaptic for x-window
Slackware Linux:
Slackware is one of the oldest distributions around and
it is very popular among experienced Linux users. Sticking with a text-based
installer and no graphical configuration tools. Where other distributions tried
hard to develop easy-to-use front ends for many common utilities, Slackware
offers no hand-holding and everything is still done through configuration files.
Because of this, Slackware is not recommended to new users.
Nevertheless, Slackware has a magic appeal to many users.
It is extremely stable and secure - very suitable for server deployment.
Experienced Linux administrators find that the distribution is less buggy as it
uses most packages in their perfect forms are infrequent although up-to-date
packages are always available for download after the official release.
Slackware is a fine distribution for those who are interested in deeper
knowledge of Linux internals.
Linux and GNU:
The Linux system is based on GNU tools (Gnu's
Not UNIX), which provide a set of standard ways to handle and use the system.
All GNU tools are open source, so they can be installed on any system. Most
distributions offer pre-compiled packages of most common tools, such as RPM
packages on RedHat and Debian packages (also called deb or dpkg) on Debian, so
you needn't be a programmer to install a package on your system. However, if
you are and like doing things yourself, you will enjoy Linux all the better, since
most distributions come with a complete set of development tools, allowing
installation of new software purely from source code. This setup also allows
you to install software even if it does not exist in a pre-packaged form
suitable for your system.
A list of common GNU
software:
·
Bash: The
GNU shell
·
GCC: The
GNU C Compiler
·
GDB: The
GNU Debugger
·
Gnome:
the GNU desktop environment
Many commercial applications are available for Linux, and
for more information about these packages we refer to their specific
documentation. Throughout this guide we will only discuss freely available
software, which comes (in most cases) with a GNU license.
To install missing or new packages, you will
need some form of software management. The most common implementations include
RPM and dpkg. RPM is the RedHat Package Manager, which is used on a variety of
Linux systems, eventhough the name does not suggest this. Dpkg is the Debian
package management system, which uses an interface called apt-get, that can manage RPM packages
as well.
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