My Tech notes: March 2009

Unix Documentation

Free Online Unix Training Materials

Lists many links to free Unix training materials.

Pointers and Arrays Materials

Pointers and Arrays materials Explained for C beginners

C FAQ and General Questions C Interview Questions

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Tuesday, March 31, 2009

AVG Antivirus Free Download a Online

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Come to CNET for free and safe AVG Anti-Virus Free Edition downloads. Protect your computer from viruses and malicious programs.

Thursday, March 26, 2009

From Windows Vista Home Edition Access SMBD ver 2.2.12

How to Access NAS Box From Windows Vista Home Edition?
Access NAS box windows vista (Ultimate editions), If you NAS box contains SMBD/ SAMBA version less than or equals 2.2.12
Steps to access NAS box from Windows Vista Home Edition
1. In the Windows taskbar, click Start and select Run. In Run window type “regedit” and press OK.
2. This will open User Account control window, here click continue.
3. Double click on the “HKEY_LOCAL_MACHINE” , “SYSTEM”, “Current Control Set” and
4. Then click on “Lsa” then you will get some parameters in the right windowpane.
5. Find for “LMCompatibilityLevel” and double click on this item.
6. In the edit window change the “Value data” to 1 from 3.
7. Press OK then Close the Registry Editor (regedit).

your Vista PC ready to access the NAS box.

Wednesday, March 25, 2009

Access NAS Box From Windows Vista Ultimate Edition

How to Access NAS Box From Windows Vista Ultimate Edition?
Access NAS box windows vista (Ultimate editions), If you NAS box contains SMBD/ SAMBA version less than or equals 2.2.12
Steps to access NAS box from Windows Vista Ultimate Edition

1. In the Windows taskbar, click Start and select Run. In Run window type “secpol.msc” and press OK.
2. This will open User Account control window, here click continue.

3. Now double click on the “Local Policies” and click on “Security Options”.
4. Find “Network Security: LAN Manager authentication level” in right windowpane and double click on this policy.

5. Now change Local Security Setting “Send NTLMv2 response only” to “Send LM & NTLM –use NTLMv2 session security if negotiated”.
6. click “apply” and then “OK”.
Now your Vista PC ready to access the NAS box.
Share your tricks also.

Thursday, March 19, 2009

How To Compile Tool Chain For Bootloader

For compiling Uboot 3.4.4 tool chain is required.
Steps to check and change tool chain correspondingly
1) At the bash prompt of your Linux PC, execute the following command.

$ tar -zxvf arm-tools.tar.gz

Now you will have the "arm-tools" folder created in your current directory.

2) Copy the "arm-tools" directory to your home directory (or wherever you
prefer to)

$ cp -rf arm-tools ~/

3) Modify the .bash_profile file in the home directory, by using the following
steps. (Add the following lines in .bash_profile)

$ vi ~/.bash_profile

This will open the file for editing. Make the following changes in the file

export HOME=$HOME/arm-tools
PATH=$PATH:$HOME/bin:$HOME/arm-tools/arm-linux/bin:$HOME/arm- tools/image_tools/:$HOME/arm-tools/image_tools/bin

export PATH

Close the ".bash_profile" file.

4) Then execute the command

$ source .bash_profile

5) To check whether arm-tools environment has been properly set or not type the
following at the prompt

$ which arm-linux-gcc

The expected output is as follows:


If the tool chain doesn't get set with by doing above step 5 logout and login
again to the system and repeat the step 5.

check out what is bootloader in embedded system.
Internal bootloader.

Wednesday, March 18, 2009

How to participate in the Linux kernel community

How to participate in the Linux kernel community? check out A GUIDE TO THE KERNEL DEVELOPMENT PROCESS
Jonathan Corbet has written a very interesting article on "how
to participate in the Linux kernel community"

Section 1 is the executive summary.

Section 2 introduces the development process, the kernel release
cycle, and the mechanics of the merge window.

Section 3 covers early-stage project planning, with an emphasis
on involving the development community as soon as possible.

Section 4 is about the coding process; several pitfalls which
have been encountered by other developers are discussed.

Section 5 talks about the process of posting patches for review.

Section 6 covers what happens after posting patches; the job is
far from done at that point.

Section 7 introduces managing patches with git and reviewing
patches posted by others.

Section 8 concludes the document with pointers to sources for
more information on kernel development.

Please take a look at the complete document at
Please click here to download the PDF version.

Tuesday, March 17, 2009

Adding Network Printer in MS windows Simplest Way

yes you can add Network Printer in MS windows in very Simplest Way. I was allocated a new windows Xp PC, I was waiting for network printer to configure on my new machine. I just tried this simplest way, rather to wait for network admin. My friend also asked me about configuration for network printer and i told him same way, which is worked for him also. Here is simplest way to configure your new printer.

go to start->settings-> Printers and Faxes

Here you can see the default printer name.
Just ask your friend about the name of network printer, and all you have to do is rename your default printer with network printer name, your printer is on. check out this trick works for you also.
Sometimes you need to select the driver for the same, from printer properties-> advanced option.

comment on your tricks also.

Sunday, March 15, 2009

Difference Between Static And Shared Libraries ?

Libraries are collection of precompiled functions which have been written to be reusable.

Libraries in Linux are classified into two types:

1) Static Libraries:- The collection of object files kept together. When a program needs a function, that is stored in static library, it includes the header file that declares the function. The compiler combines the program code and linker links the library into an execuatble code.

Static Libraries are also called as archives that ends with .a extension.

e.g. /usr/lib/libc.a is a standard C library.

Disadvantage of Static Libraries:- In the static libraries the function code is included in the executable. So when we run many applications that use the same function code, we end up with many copies of same functions in memory.

2) Shared Libraries:- When a program uses a function in a shared library, then that code does not get included in the execuatable. Instead it references to shared code that will be made available at run time. So when that program is loaded in memory to execute, the functions references are resolved and calls are maded to shared libraries which will be loaded into memory.

So many applications uses a single copy of shared libraries. Also shared libraries can be updated independently of the applications that rely on it.

Shared libraries has the form

name - name of library so - extension N - major revision number


Shared libraries(.so) are just like Dynamic Link Libraries(.dll) in Windows.

Thursday, March 5, 2009

Loop Unrolling or Loop unwinding in C

What is Loop Unrolling or Loop unwinding in C?
Loop unwinding, also known as loop unrolling, is a loop transformation technique that attempts optimize a program's execution speed at the expense of its size.
The goal of loop unwinding is to increase the program's speed by reducing (or eliminating) the "end of loop" test on each iteration. Loops can be re-written as a sequence of independent statements which eliminates the loop controller overhead.
The major side effects of loop unrolling is The increased register usage in a single iteration to store temporary variables (though much will depend on possible optimizations), which may hurt performance.
The code size expansion after the unrolling, which is undesirable for embedded applications and for purposes of code readability. Large code can also cause an increase in instruction cache misses, which may adversely affect performance.
A simple example
A procedure in a computer program is to delete 100 items from a collection. This is accomplished by means of a for-loop which calls the function delete(item_number):

for (int x = 0; x <>

If this part of the program is to be optimized, and the overhead of the loop requires significant resources compared to that for delete(x), loop unwinding can be used to speed it up. This will result in an optimized code fragment like:

for (int x = 0; x <>

As a result of this modification, the new program has to make only twenty loops, instead of a hundred.

check example here.

Wednesday, March 4, 2009

Access Samba Using Dos Commands List Here

I was searching for accessing samba using DOS command, Finally I managed it by own; here is list of useful command.
To mount or to map the SAMBA folder to local machine.
eg; to map public folder from and copy test.txt
use :- net use z: \\computer\folder
Map the Z: drive to the network path //computer/folder.
net use z: \\\public

enter user-name (if connecting first time)
enter password

To copy the data to this drive

ie to put file
copy test.txt \\\public

to get the file
copy \\\public\test.txt

To delete the connection
net use z: /del /yes

Tuesday, March 3, 2009

Scientists discover oldest words in the English language

The oldest words in the English language include "I" and "who", while words like "dirty" could die out relatively quickly, British researchers said Thursday.
clipped from

Scientists discover oldest words in the English language, predict which ones are likely to disappear

Scientists at the University of Reading have discovered that 'I', 'we', 'who' and the numbers '1', '2' and '3' are amongst the oldest words, not only in English, but across all Indo-European languages. What's more, words like 'squeeze', 'guts', 'stick', 'throw' and 'dirty' look like they are heading for history's dustbin - along with a host of others
Evolutionary language scientistsfrom the University of Reading
have been investigating how languages evolve, and whether that evolution followed any rules. Until recently they believed they would not be able to track words back in time for more than 5,000 years, however their new IBM supercomputerhas enabled them to go back almost 30,000 years, and finally provide the answers
Supercomputers are enabling the world to become increasingly interconnected, instrumented and intelligent
 blog it