What Is The Linux Operating System
A brief Introduction to the history of Linux and some important command prompts to get you started.
Linux, a UNIX clone, is an operating system that embodies the concept of complete transparency. One of the most important aspects of Linux is that it has been developed and supported by its users, making it relatively easy to get your hands on one of the many free Linux distributions. But although Linux is growing in popularity, there are still people who consider this operating system a toy or pet; something to play with, but not to be taken seriously. Until recently, Linux was reserved for self avowed hackers and enthusiasts. This was mainly because Linux was not very user-friendly. Now, with an intuitive graphical user interface or GUI, Linux is as user friendly as Windows. You do not need to be a rocket scientist to use Linux with the GUI. In fact, a Linux Desktop looks much like a Windows Desktop (with a few added features). Linux has at least a dozen different highly configurable graphical interfaces, which runs on top of a Xfree86.
In 1969, AT&T Bell Laboratories introduced the UNIX operating system. This was based on the C Language. Many know C as a language used in programming. Today, a wide variety of languages including C++, Java, Perl, and C Sharp are also available. Originally, UNIX was released for free to universities. UNIX is the basis for several clones, including Linux and DSB. Richard Stallman founded the GNU Project in 1984. This project was created for free distribution. This was in stark contrast to the Microsoft-style licenses that restricted distribution and modification. Richard’s ultimate goal was to create a complete UNIX-like operating system using a server set called HURD. It was not until 1989 that the GNU project released their free license. This license was to be known as the General Public Licence (GPL). Linux would eventually be released under this license.
Tim Berner-Lee, who was working as a researcher at CERN, developed hypertext Markup Language in 1990. And thus, the World Wide Web was created. One year later in 1991, an undergraduate computer Science major at the University of Helsinki, Finland, began developing a new operating system. His name: Linus Torvalds. The system would later become known as Linux. Linux kernel 0.02 was the first public release. Kernel 0.11 followed shortly and 0.95 was released soon after in 1992. Kernel 0.95 came very close to being a fully featured kernel. Two years layer, kernel 1.0 was publicly released.
KDE is a well-known graphical interface found with most Linux Systems today. The KDE project was founded in 1996. Linux was now accessible to the general computer user. Before KDE, it was very difficult to use Linux unless you were an expert. By 1997 saw the release of Linux Kernel 2.0 the GIMP version 1.0. GIMP is a graphics program that can certainly rival Adobe Photoshop. In the following two years Linux grew so rapidly Eric S. Raymond revealed in the so-called Halloween Documents that the new open source movement seriously threatened Microsoft. It is hard to believe, but GNOME 1.0 and KDE version 1.1 were only released in 1999 and Red Hat Software had only filed their preliminary papers for an initial public offering.
Today, Linux is used by both business and home-users alike. It can run on various Intel, Apple, palmtop PDA and AMD based hardware from the 386 up. Most Linux Distributions (free /not) come crammed with loads of free software. Some of the more common software that come with most Linux Packages include Graphical User Interfaces like GNOME and KDE, graphical editing facilities such as the popular GIMP (Graphics Image Manipulation Program), Development tools (Compilers and debuggers), office products and games.
Now that we have been thoroughly versed on the history of Linux, I would like to take you into the Linux System. This is no way an epic journey into Linux. That would take far too long, we will just be scraping the surface of a very complex operating system.
First and foremost, it is important to get to know a few terms that will crop up whenever Linux is discussed.
The two most popular graphical interfaces are KDE and GNOME. As I mentioned earlier, the first graphical interface introduced by Linux was KDE (Common Desktop Environment). This is the industry standard for Linux. GNOME is the latest user interface.
When exploring your Linux System through the shell (a window similar to the DOS Prompt), there are some directories and commands you will need to know. One thing you will notice about the command prompt and terms used by Linux; they are very literal. As an example consider the mount and umount commands. Mount is used literally the command to mount the disk be it the CD-ROM, Floppy or hard drive. And Umount; dismounts. So it is not difficult to decipher some of the commands.
To begin with, type “ls”. This command is the same as the “dir” command in DOS. If you type “ls –al”, you get a line for line listing of the directory with permissions, type and size. You will see the boot directory listed here (if you are in c:/) This is where your operating system will boot. The /etc directory contains all the config files. Do not mess around here. To enter the /etc directory, you would type /etc/.
When you type cd /home you will be taken back to the home directory. CD is the same as in DOS; change directory. You would treat it the same as in DOS. /Lost + Found is an interesting directory. Anything that Linux does not know what to do with lands up here. The /mnt directory contains all the mounted devices. /lib is your library, all c and c++ libraries sit here. DO NOT FIDDLE with this directory, you land up with a mess on your hands. All programs that have output can be found in either the /opt , /bin , or /usr/bin directory and process information is found in the /proc directory. /temp, holds your temporary files. This is one of the greatest features of Linux, as the temp directory is very controlled. You will find the event log at /var.
Remember to log on as “root” if you want to make any changes to your system. This includes directory permissions. Linux has a very simple, but efficient permissions system that, as root, you can easily modify.
Let us look at an example of permissions set on a directory or folder:
d rwx r-x r-x
This can be read to mean the following
D = what you are dealing with. In this case, it is a directory
The second set of permissions applies to the owner of that directory (rwx). Here the owner has Read, Write and execute permissions. The next set (r-x) applies to the group. In this case the group has only Read and Execute permissions. The final set of permissions (r-x) belongs to any other users. To help you understand how to change permissions, we will make a directory.
Type:
Mk dir test
The word test, is the name of the directory. You may give it any name you wish)
Permissions are set with an octal weight. The weights are as follows:-
READ = 4
WRITE = 2
EXECUTE = 1
That is a total weight of 7. To allow all permissions on the new directory, you would type:-
Chmod 777 test
Explanation:
CHMOD = change mode
777 = Full permission
test = directory name
You would now see the directory listed like this:- d rwx rwx rwx.
Typing 757 (instead of 777) would allow read, write and execute, read and execute, read, write and execute (rwx r-x rwx). You can modify permissions by changing these numbers. Remember that each number pertains to it’s particular user group (owner, group or other). The numbers are divided into these three groups.
Owner Group Others
7 7 7
Rwx Rwx Rwx
4 + 2 +1 4 + 2 +1 4 + 2 +1
To change permission, you would subtract the relevant octal weight.
i.e
Rwx R-x Rwx
4 + 2 +1 4 +1 4 + 2 +1
7 5 7
Therefore, the command would read chmod 757test
Now we will change the ownership of this directory:
Chown me test
Explanation:
Chown = change owner
Me = new owner’s name (this you would have to decide on)
Test = directory name
To change a group the command line would read “chgrp”, inserting the new group’s name.
Linux is full of possibilities and it is open for you to explore. If you are running the SuSE version of linux, take time to look at YAST (Yet Another Setup Tool). I am not joking; it is really called that. You can add users, install programs and change configurations. Only root has access to YAST and SAX. Sax is used to set up your display and mouse. These things should have been done on installation, but if you need to make changes or run into problems, this is where you should begin looking.
Have a great time exploring Linux: you will soon find yourself hooked.
Written by Sandra D Shirlow.
