My new blog www.tiplite.com

Please visit my new blog http://www.tiplite.com

Linux Technical Days: Day1 - What is Linux?

What is Linux?

Linux is the name usually given to any Unix-like computer operating system that uses the Linux kernel. Linux is one of the most prominent examples of free software and open source development: typically all underlying source code can be freely modified, used, and redistributed by anyone. The name "Linux" comes from the Linux kernel, started in 1991 by Linus Torvalds. The system's utilities and libraries usually come from the GNU operating system, announced in 1983 by Richard Stallman. The GNU contribution is the basis for the alternative name GNU/Linux.

Linux history:

The Unix operating system was widely adopted, copied and modified by academic institutions and businesses. By 1990 most universities had Unix systems and computer science students were exposed to them. Many of them wanted to run Unix on their own computers as well. Unfortunately, by that time, Unix had become commercial and rather expensive. About the only cheap option was Minix, a limited Unix-like system written by Andrew Tanenbaum for teaching purposes. The GNU Project, started in 1984, had the goal of creating a "complete Unix-compatible software system" made entirely of free software. In 1985, Richard Stallman created the Free Software Foundation and developed the GNU General Public License (GNU GPL). Many of the programs required in an OS (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed by the early 1990s, although low level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Into this scene came Linux, in October, 1991. Linus Torvalds, the author, had used Unix at the University of Helsinki, and wanted something similar on his PC at home. Since the commercial alternatives were way too expensive, he started out with Minix, but wanted something better and soon started to write his own operating system. After its first release, it soon attracted the attention of several other hackers. While Linux initially was not really useful except as a toy, it soon gathered enough features to be interesting even for people uninterested in operating system development. During 1992 and 1993, the Linux kernel gathered all the necessary features it required to work as a replacement for Unix workstations, including TCP/IP networking and a graphical windowing system (the X Window System). Linux also received plenty of industry attention, and several small companies were started to develop and distribute Linux. Dozens of user groups were founded, and the Linux Journal magazine started to appear in early 1994. Version 1.0 of the Linux kernel was released in March, 1994. Since then, the kernel has gone through many development cycles, each culminating in a stable version. Each development cycle has taken a year or three, and has involved redesigning and rewriting large parts of the kernel to deal with changes in hardware (for example, new ways to connect peripherals, such as USB) and to meet increased speed requirements as people apply Linux to larger and larger systems (or smaller and smaller ones: embedded Linux is becoming a hot topic). From a marketing and political point of view, after the 1.0 release the next huge step happened in 1997, when Netscape decided to release their web browser as free software (the term 'open source' was created for this). This was the occasion that first brought free software to the attention of the whole computing world for the time. It has taken years of work since then, but free software (whether called that or open source) has become not only generally accepted but also often the preferred choice for many applications.

Why to use Linux?

• Freedom: Linux and most of its software are distributed under the GNU Public License or a similar license; licenses that allow anyone to modify the internal code of the software to fit their individual needs or to provide improvements. So those software are owned by anybody as he respects the license.
• Price: many Linux distribution comes free of charge and can be downloaded freely from the internet. Also most software used for Linux comes free of charge.
• Security:
• Well-done administration of a computer with Linux allows for a very secure multi-user workstation.
• Viruses are less of a threat now. The system setup of a Linux system does not allow a virus to act.
• Transparent: With Linux, you can always find out what the system is doing, and why. All configuration files are in plain text. Linux will do what you ask it for, no more, no less. It doesn't do magic stuff behind your back.
• Born on the Internet: Linux has been network enabled since the very beginning. Networking and Internet tools are built into the system. Linux is the leading operating system for Internet servers.
• Standards: Linux itself and many common applications follow open standards. This means an update on one system will not make other systems obsolete.
• Linux is configurable: Linux is a true multi-user operating system. Each user can have his or her own individual configuration all on one computer.

Linux distributions:

As Linux is a free open source software, many communities and companies started to build system based on Linux. This communities customizes and creates software that is shipped with these systems. This combination of Linux kernel, GNU tools and community created software is called a distribution. A distribution gives the user the ability to manage and configure the system easily as it add tools that automates those operations. There are many distributions on the Internet which are in a competition to offers the best. More about available distributions and their ranks by users are available at http://distrowatch.com. You can choose the distribution which you like and download it directly and legally from its official site and start right ahead after burning you distribution CD. It is preferred to try a Live CD before installing the system on your hard disk. Live CD is a CD that contains a fully running Linux OS that runs directly from the CD without installing or altering any files on your hard disk and without any risk.

Refernces

http://en.wikipedia.org/wiki/Linux http://liw.iki.fi/liw/texts/linux-the-big-picture.html http://distrowatch.com http://www.tuxmagazine.com/node/1000117

My Timer Label Swing Component

For sometime I wanted to create a swing component and for some business issues I wanted to calculate time I worked to calculate my payments. So I created a program that counts time in milliseconds. Then I wanted to create the same program with more features and thought if some other programs may need such component. Here comes the idea of extending Java Swing JLabel component to have the time counter then use it whenever possible and distribute it for other developers.

You can download the component from the link: http://www.4shared.com/file/45525258/ea7339d0/TimerLabel.html

NetBeans is recommended for development. You can add the component by adding it to the palette of swing by using the palette manager the "Add from jar" and select my jar file which contains TimerLabel class which represents the component.

The component contains three main functions:

• start(): which starts the timer.
• pause(): pause the running timer.
• reset() resets the timer to zero state.
  

you can find further documentation in doc folder.

Slow Linux Internet? Here is a solution

Some distribution such as Debian etch enable IPv6 by default (I don't know why to use IPv6 now). This may cause the internet connection to slow down as the system searches for IPv6 first and most of internet connections uses IPv4 (which is the appropriate one).

To fix this problem you need to edit file /etc/modprobe.d/aliases to disable IPv6 support. Edit the file and search for the line:

alias net-pf-10 ipv6

and edit it to be:

alias net-pf-10 off #ipv6

Then reboot your machine to enable new settings and enjoy flawless speed.

My own distro screenshots

This is some screen shots for my own Linux distribution which I've built from scratch.

How to think like a computer scientist

This is a series of books for different programing languages including C++, python and Java. It is a very good series that focuses on how the programmer should think including using different data structures and developing methods. the series' books could be found at:
C++: http://ibiblio.org/obp/thinkCS/cpp/english/dist/thinkCScpp.html.tgz
Python: http://ibiblio.org/obp/thinkCS/python/english2e.tgz
Java: http://ibiblio.org/obp/thinkCS/java/english/dist_v4.0/thinkapjava.pdf

A lot of java examples

http://www.exampledepot.com/

This site offers a lot of Java examples on almost every class of J2SE. It includes also HowTOs to perform different tasks using thse classes I hope you Enjoy it.

Bad User

I've heard a lot of people saying that their hared disks was damaged because of trying to setup Linux or so. At last few days It was approved that not the OS which is the real problem but the problem is the bad use of the OS tools.

For example a check disk tool for windows damaged my most valuable partition with my most valuable data. I'm sure that I was the real cause. The story begins after a forced check disk at the startup of the Windows OS in a dual boot machine with Windows XP SP2 and Fedora Core 6. After the check I found no data on the partition. I've tried several times to restore the data but failed. Then I thought to use fsck.vfat utility in Linux the data was restored perfectly, so I restored some data into CDs and other partitions. After rebooting to Windows again it forced the check disk another time and returned to the starting point. I tried again to use Windows chkdsk to restore my data one of my tries ended with all data on the partition lost.

What I want to say is that the OS isn't the main reason for destroying data and hard disks but the main problem is the bad use of tools that may lead into lose of data. So don't accuse any tool of your bad use. At the end and beginning I thank my god that I've restored my most most important data.

The beginning

Welcome back,

I just want to start my tutorials of c++. To start a compiler, the program that translates source code into executable or runnable format that can be executed, is needed. My preferred compiler is GCC which is GNU Compiler Collection which is a collection of compilers for various languages, basically c and c++. It is shipped by default with most Linux distributions. A version for Microsoft Windows is available from the site http://www.mingw.org. Also an Integrated Development Environment, IDE, is available with a version of this compiler from http://www.bloodshed.net.

The installation of the compiler is so easy. for Linux it may be installed by default for most distribution if it is not you can install it using your distro program installation instruction. for example:

for Debian or Ubuntu as root:

apt-get update
apt-get install gcc g++

For Microsoft windows just run the installation program and follow install instructions.

The start will be with console applications, application that runs from the command line and uses only monitor as output and keyboard as input. Those applications will be used to learn the basics of the language and programming in general. Then we may advance to programming Graphical User Interface (GUI) based application using the QT library, an open source library for developing GUI applications, to know the basics of GUI applications.

Windows Server 2003 First Impression

My first impression of Windows Server 2003 is that "Windows is not easy" as know I've faced many problems that I couldn't solve it easily nor solve it at all. The first problem I've faced that newer versions of Microsoft software doesn't support the system (I don't know how a company doesn't support its OS for its programs). Then I tried to install updates (Service Packs) and I was surprised because of the dependencies it requires. It requires .NET Framework 1.1 not earlier than SP1 (This version comes with .NET framework 1.1 but not service pack1) and BITS server 2 (it comes also with bits server 1).

After this very small experience with such OS, I've found that Linux was so easy for server management. despite of I was editing its configuration files and typing commands but at least the system shipped with embedded help system (Manual and Info pages) which I've learned so much from. At the opposite side I've found that is no helpful help in the so called Windows Server.

Another point is the hardware devices drivers non of the hardware drivers was installed at the opposite side Linux have installed all my device perfectly, even the win modem driver was installed so easy by myself.

At last a word for those are using Microsoft products for it easiness I say Windows is not easy as you may thought. It also requires some patience to learn how to administrate as every thing in live is at least in the world of software. So think before choosing.

GPL the mother of all open source

The free software foundation (FSF) has created the GPL to protect its software and protect the right of these software users. It says that everyone has the right to obtain, modify, distribute
the software with the condition of keeping the right of the author.
Here is the script of the GPL v2 Licence:

GNU GENERAL PUBLIC LICENSE
Version 2, June
1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not
allowed.

Preamble

The licenses for most software are designed to take away
your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users.
This General Public License applies to most of the Free
Software Foundation's software and to any other program whose authors commit to using it.(Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.

To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.

We protect your rights with two steps:

(1) copyright the software, and
(2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.

Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations.

Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary.

To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.

The precise terms and conditions for copying, distribution
and modification follow.

GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public
License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program).

Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.

2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:
a) You must cause the modified files to carry prominent
notices stating that you changed the files and the date of any change.
b)You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
c) If the modified program normally reads commands
interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and
that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)
These requirements apply to the modified work as a
whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.
In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

b) Accompany it with a written offer, valid for at least
three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as
a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

If distribution of executable or object code is made by
offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code.

4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to
do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.

6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions.

You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties
to this License.

7. If, as a consequence of a court judgment or allegation
of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under any particular
circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other circumstances.

It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice.
This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.

8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License.

9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

Each version is given a distinguishing version number.
If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.

10. If you wish to incorporate parts of the Program
into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally.

NO WARRANTY

11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED ARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE EFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY
OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

END OF
TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs?

If you develop a new program, and you want it to be of the
greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found.

Copyright (C) <year><name>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names:

Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers)
written by James Hacker, 1 April 1989

TyCoon, President of Vice
This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library.

If this is what you want to do, use the GNU Library General
Public License instead of this License.

Welcome to my Computer Science Blog

Welcome to my computer science blog where I'm intending to offer some computer science tutorials; more specifically programming languages tutorials such as C++, Java, python and whatever I could either than those main topic. Also I'll introduce some Linux tips & tricks either for beginners and advanced users to make maximum use of this powerful OS.