Quick references

• Linux Quick Reference
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/linux-quick-reference
• 
  Regular Expressions
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/regular-expressions-quick-reference
• 
  LINUX Administrator
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/linux-administrator%E2%80%99s-quick-reference
• 
  Unix/Linux Command Reference
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/unixlinux-command-reference
• 
  Vi Quick Reference
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/vi-quick-reference
• 
  Bash Pocket Reference
  http://tips-linux.net/en/linux-ubuntu/linux-books/linux-quick-reference/bash-pocket-reference

How to install wireless BMC4311 with Fedora 14

[root@nilesh ~]# yum install b43-fwcutter

Loaded plugins: langpacks, presto, refresh-packagekit
Adding en_US to language list
Setting up Install Process
Package b43-fwcutter-013-2.fc14.i686 already installed and latest version
Nothing to do

[root@nilesh ~]# cd /tmp/

[root@nilesh tmp]# wget http://downloads.openwrt.org/sources/broadcom-wl-4.150.10.5.tar.bz2

Command not found.
Install package 'wget' to provide command 'wget'? [N/y] [root@nilesh tmp]# y
Command not found.

[root@nilesh tmp]# yum install wget

Loaded plugins: langpacks, presto, refresh-packagekit
Adding en_US to language list
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package wget.i686 0:1.12-2.fc13 set to be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
Package         Arch            Version                Repository         Size
================================================================================
Installing:
wget            i686            1.12-2.fc13            fedora            480 k

Transaction Summary
================================================================================
Install       1 Package(s)

Total download size: 480 k
Installed size: 1.8 M
Is this ok [y/N]: y
Downloading Packages:
Setting up and reading Presto delta metadata
Processing delta metadata
Package(s) data still to download: 480 k
wget-1.12-2.fc13.i686.rpm                                | 480 kB     00:03    
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing     : wget-1.12-2.fc13.i686                                    1/1

Installed:
wget.i686 0:1.12-2.fc13                                                      

Complete!

[root@nilesh tmp]# wget http://downloads.openwrt.org/sources/broadcom-wl-4.150.10.5.tar.bz2

--2011-05-03 08:18:57--  http://downloads.openwrt.org/sources/broadcom-wl-4.150.10.5.tar.bz2
Resolving downloads.openwrt.org... 78.24.191.177
Connecting to downloads.openwrt.org|78.24.191.177|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3888794 (3.7M) [text/plain]
Saving to: “broadcom-wl-4.150.10.5.tar.bz2”

100%[======================================>] 3,888,794    128K/s   in 30s    

2011-05-03 08:19:28 (125 KB/s) - “broadcom-wl-4.150.10.5.tar.bz2” saved [3888794/3888794]

[root@nilesh tmp]# cp broadcom-wl-4.150.10.5.tar.bz2 /lib/firmware/

[root@nilesh tmp]# cd /lib/firmware/

[root@nilesh firmware]# tar -jxf broadcom-wl-4.150.10.5.tar.bz2

[root@nilesh firmware]# cd broadcom-wl-4.150.10.5

[root@nilesh broadcom-wl-4.150.10.5]# cd driver/

[root@nilesh driver]# ls

config         wl_ap_mimo.o  wl_apsta_micro.o  wl_apsta.o      wl_sta_mimo.o
wl_ap_micro.o  wl_ap.o       wl_apsta_mimo.o   wl_sta_micro.o  wl_sta.o

[root@nilesh driver]# b43-fwcutter -w /lib/firmware/ wl_apsta_mimo.o

This file is recognised as:
ID         :  FW13
filename   :  wl_apsta_mimo.o
version    :  410.2160
MD5        :  cb8d70972b885b1f8883b943c0261a3c
Extracting b43/pcm5.fw
Extracting b43/ucode15.fw
Extracting b43/ucode14.fw
Extracting b43/ucode13.fw
Extracting b43/ucode11.fw
Extracting b43/ucode9.fw
Extracting b43/ucode5.fw
Extracting b43/lp0bsinitvals15.fw
Extracting b43/lp0initvals15.fw
Extracting b43/lp0bsinitvals14.fw
Extracting b43/lp0initvals14.fw
Extracting b43/a0g1bsinitvals13.fw
Extracting b43/a0g1initvals13.fw
Extracting b43/b0g0bsinitvals13.fw
Extracting b43/b0g0initvals13.fw
Extracting b43/lp0bsinitvals13.fw
Extracting b43/lp0initvals13.fw
Extracting b43/n0absinitvals11.fw
Extracting b43/n0bsinitvals11.fw
Extracting b43/n0initvals11.fw
Extracting b43/a0g1bsinitvals9.fw
Extracting b43/a0g0bsinitvals9.fw
Extracting b43/a0g1initvals9.fw
Extracting b43/a0g0initvals9.fw
Extracting b43/b0g0bsinitvals9.fw
Extracting b43/b0g0initvals9.fw
Extracting b43/a0g1bsinitvals5.fw
Extracting b43/a0g0bsinitvals5.fw
Extracting b43/a0g1initvals5.fw
Extracting b43/a0g0initvals5.fw
Extracting b43/b0g0bsinitvals5.fw
Extracting b43/b0g0initvals5.fw
[root@nilesh driver]#

I got some selinux warning so I disabled it and run the command again.

[root@nilesh driver]# b43-fwcutter -w /lib/firmware/ wl_apsta_mimo.o

This file is recognised as:
ID         :  FW13
filename   :  wl_apsta_mimo.o
version    :  410.2160
MD5        :  cb8d70972b885b1f8883b943c0261a3c
Extracting b43/pcm5.fw
Extracting b43/ucode15.fw
Extracting b43/ucode14.fw
Extracting b43/ucode13.fw
Extracting b43/ucode11.fw
Extracting b43/ucode9.fw
Extracting b43/ucode5.fw
Extracting b43/lp0bsinitvals15.fw
Extracting b43/lp0initvals15.fw
Extracting b43/lp0bsinitvals14.fw
Extracting b43/lp0initvals14.fw
Extracting b43/a0g1bsinitvals13.fw
Extracting b43/a0g1initvals13.fw
Extracting b43/b0g0bsinitvals13.fw
Extracting b43/b0g0initvals13.fw
Extracting b43/lp0bsinitvals13.fw
Extracting b43/lp0initvals13.fw
Extracting b43/n0absinitvals11.fw
Extracting b43/n0bsinitvals11.fw
Extracting b43/n0initvals11.fw
Extracting b43/a0g1bsinitvals9.fw
Extracting b43/a0g0bsinitvals9.fw
Extracting b43/a0g1initvals9.fw
Extracting b43/a0g0initvals9.fw
Extracting b43/b0g0bsinitvals9.fw
Extracting b43/b0g0initvals9.fw
Extracting b43/a0g1bsinitvals5.fw
Extracting b43/a0g0bsinitvals5.fw
Extracting b43/a0g1initvals5.fw
Extracting b43/a0g0initvals5.fw
Extracting b43/b0g0bsinitvals5.fw
Extracting b43/b0g0initvals5.fw
[root@nilesh driver]#

Now just try the to establish connection with your wireless card and check working or not.

Please always check your logs when ever you want to do some setup.

In my case

#tail -f /var/log/messages

May  2 22:29:09 nilesh kernel: [   27.735949] b43-phy0 ERROR: Firmware file "b43/ucode13.fw" not found
May  2 22:29:09 nilesh kernel: [   27.735961] b43-phy0 ERROR: Firmware file "b43-open/ucode13.fw" not found
May  2 22:29:09 nilesh kernel: [   27.735969] b43-phy0 ERROR: You must go to http://wireless.kernel.org/en/users/Drivers/b43#devicefirmware and download the correct firmware for this driver version. Please carefully read all instructions on this website.

-

Free PDFs............Download Now

http://notes.nap.edu

Makes the permissions of file2 the same as file1

$ chmod --reference file1 file2



Ex:
arul@arul-desktop:~$ ls -ll
drwxr-xr-x 1 arul arul       134 2011-01-16 02:09 ruby-samples
drwx------ 1 arul arul        96 2011-02-19 01:43 python-ex

arul@arul-desktop:~$ chmod --reference ruby-samples/ python-ex
drwxr-xr-x 1 arul arul       134 2011-01-16 02:09 ruby-samples
drwxr-xr-x 1 arul arul        96 2011-02-19 01:43 python-ex

Want your computer speak the current time? (LINUX)

Want your computer speak the current time?

$ saytime


This command says the current system in a male voice. If you are ambitious, you can write a shell script to set up an alarm which will say the time.


saytime: speaks the current time through your sound card Say the current time through your sound card. Requires you have a sound output device available.

Save Nature

Creative poster campaign against the Global Warming and Climate change. To realize the disaster of global warming if we still play with Nature.

Wildlife is disappearing

15 Km of rain forest disappears every minute

Very soon their will be no Tiger – Search Result

Fashion claims more victims than you think

Consuming the Earth is consuming our future

We fight every day for our extinction

The Tsunami killed 100 times more people than 9/11

Global warming is chnaging the world’s climate rapidly. Icebergs are melting, oceans are rising, nature is reversing. Act now, conserve energy and treat the planet with respect or we’ll have a world at sea.

Polluted river water kills as many people as a nuclear explosion

Give a Hand to Wildlife

Loyal Pet fight against destiny – Try to be loyal to nature before its too late

What is Air conditioner ?

 Ever since the industrial age began, man has thought of hundreds of ways to outsmart nature. And out of those hundred times, man has succeeded in more than ninety nine times. Climate and weather too have been brought together as a symphony that man desires to hear. Air-conditioning is the name of the scientific method that defies unruly sun, freezing winters and humid airs. Once a sci-fi author Rober Heinklein had said “Climate is what you expect, weather is what you get.” Truly, with air-conditioner we get what we expect.

 

What we know as air conditioning is rather an innovative and as unique technology, but for ages, different techniques of dehumidifying and cooling air have always been around and practiced in different parts of the world. The seeds of this thoughtful invention called air-conditioner were sown ages back when handmade fans gave way to electric fans and coolers and finally the 21^st century woke up to the AC that marked the onset of temperature ruled by man. The wealthiest of ancient Romans put to use aqua duct water and circulated it through the walls of their mansions. At the same time, the Chinese too used varied methods to keep the interiors of their buildings cool s by utilizing air and water in the hottest of time.

 

In the 1800’s, a man came as close to inventing an air-conditioner as one could. The British inventor Michael Faraday found out that Ammonia on being compressed and liquidized could help in cooling the air. Later on the same lines, John Gorrie, in the year 1841, discovered that the same compressing technology could be put to best use in his hospital in Florida. Utilizing this technology, he created ice to keep his patients’ rooms. Unlike Faraday, Gorrie didn’t stop at the mere discovery, and continued his experiments with the new found technology. He came very close to inventing the first air-conditioning unit, but unfortunately his first pro type leaked and resulted to be a failure. Instead of stepping back and disappearing in the darks of failure, Gorrie secured some funds and finally got his patent approved in the year 1851. For his hard luck, his funding partner died and left him with the shattered dream of indoor air-conditioning unrealized. Gorrie too succumbed to death in 1855 and with him, the air-conditioning science too died for the next 50 years.

Again, work started on the science of air-conditioning and the first air-conditioner was designed in 1902. It was initially designed for industrial purposes. The inventor or “Father of Cool” Willis Carrier used coils to control moisture in the air and at the same time maintain the cool to prevent wrinkling of paper in a printing plant. It was only one year after Carrier graduated with a Masters in Engineering from Cornell University that he saw the first air conditioning in operation. He figured out that he could make the Brooklyn printing plant owner happy through his air-conditioning coils. These coils created a stable environment with which aligned four-color printing could be possible.

 

Happy with the success of the first system, Carrier established the pioneer mass plant for air-conditioners. The term air-conditioning was coined by Stuart W. Cramer in the year 1906. He belonged to Charlotte, North Carolina and was finding out ways he could add moisture to the air in his textile plants. The first usage of this term happened in the papers he had filed to the patent offices for the water conditioning unit invented by him. These inventions happened parallel to each other, and fascinated by the name, Carrier took this term air-conditioning and added it to his companies’ name. 

 

The first air-conditioner was bulky, reproduced huge noises and gave out toxic chemicals too. These toxins namely, ammonia, methyl chloride and propane, were inflammable and when leaked caused fatal effects in the atmosphere and even to the human lives. In 1928, an air-conditioner was built using Freon which was considered much safer for humans though it was hazardous for the environment. Thomas Midgley was the inventor of this Freon using air-conditioner. Even after the human friendly air-conditioner was launched, the general public except those who lived luxuriously enjoyed the air-conditioning in the movie theaters alone. In the 1930s most of the theaters were utilizing the cooling technology and even during the Great Depression, people could enjoy the artificial chilly air in the theaters, even the rich proprietors, who had to give away their luxurious ACs. The system that was used in the theaters was produced by Carrier and was sold at high rates ranging between $10,000 and $50,000.

 

Air-conditioners were a luxury limited to the rich sections of the society but that was only in the early 1930s and 1940s. Slowly with steady steps, Air-conditioning walked into the corporate world and demanded the bosses to provide their employees with the comfort of ACs. Followed by a bit of retaliation at first, the bosses finally gave in and the employees worked in the comforts of artificial cold air and gave better output. The wave of air-conditioning spread world-wide and by 1957, most of the offices had air-conditioners installed as 90% of the companies according to Gail Cooper's Air-Conditioning America saw air-conditioning as the most vital factor in the increased office efficiency.

 

America led when it came to Air-conditioner adoption and by 1980s it grew as the nation that was consuming most of the air-conditioning as compared to all the other countries combined. Soon criticism too boiled up and people started lamenting the invention that concentrated on devouring the electricity and then gave out mechanical cooling. But more than criticism, Air-conditioning has always been credited with survival and growth of various industries, the development of heat sensitive computers, and what not. If not for the Air-Conditioners, how would we have survived through the record-breaking temperatures? The bulky ACs have now shrunken and are no more noisy. The emission of chemicals too doesn’t happen and besides all these improvements efforts are continued to be made to improve air-conditioning and the emphasis is now on energy conservation and efficiency. In the nearing future we can hope to see the best of air-conditioners with distinguishing features and sophisticated technology.

Linux in Web Browser

http://bellard.org/jslinux/

What is Adaptor ?

In today’s world most of the electronic appliances needs DC voltages from 3-12volts for operation. An adaptor is a device which is used to convert high AC voltages to low DC voltage. Adaptors come in various shapes, sizes & configuration depending on the use. In some cases adaptors are used to provide power to electronic appliances like video games, modems etc and in some cases they are used to charge the primary battery of the electronic device and also act as alternate power source like mobile chargers, laptop chargers, cell chargers etc. A typical adaptor is shown in the figure below.

 

 

The left red knob changes the output voltage while the right one is used to change the polarity of output voltage.

An adaptor works in these 3 simple steps:

1.      AC voltage is stepped down using a Transformer

2.      A rectifier circuit changes the AC signal to DC signal.

3.      A capacitor filters the signal to smooth DC waveform.

 

 

On removing the outer plastic body of the transformer the first glimpse of the transformer is shown in the image above.

 

 

In above image, you can see a clear picture of how transformer is fitted into the adaptor. The two green color wires takes input from the AC supply and are connected to the primary winding of the transformer. The copper wires on the right side are the output wires of transformer coming out of the secondary winding and connected to the rectifier circuit. You can see there are a number of output wires on the secondary side which corresponds to the different output DC voltage.

 

 

The above image shows the plate attached with the voltage regulator knob which connect the plate with different output wire. While we rotate the knob, the plate moves accordingly and connects with different output wires.

 

 

The above image shows the full wave rectifier circuit with four diodes mounted on the PCB which converts the AC signal to DC signal.

 

 

The capacitor is connected in the circuit to filter the ripples from output DC voltage.

 

 

A step down transformer used in adaptor is shown in the above image.

 

Working: AC adaptor works by having a transformer, a rectifying circuit and a capacitor to filter the signal. Input AC signal directly enters in the primary coil of the transformer. Transformer steps down the input AC voltage and gives low AC voltage as output from the secondary coils. The different numbers of output coils are used to provide different AC output voltages. A selector switch is used to select which output of transformer secondary must be connected to rectifier circuit. For example in order to take 6V DC output from the adaptor the secondary coil of transformer which provides 6V AC as output is connected to the input of rectifier circuit. Finally a capacitor attached with the rectifier circuit removes the AC ripples to give a smooth DC output.  

What is Capacitor ?

Capacitor is a widely used electronic component. It stores electric charge and then discharges it into the circuit. It blocks the direct current and allows the alternating current to pass through it. Depending on the purpose, there are a variety of capacitors being used like ceramic, electrolytic, mylar, mica, etc. We will explore an electrolytic capacitor through this article.

 

Structure of a Capacitor: A capacitor contains two conductor plates which are generally made of metal and an insulator between them. This insulator also known as dielectric is made up of material like paper, plastic, ceramic or glass. The two plates are electrically connected to the external circuit with the help of two thin metal rods also known as the legs of the capacitor.

 

These two plates are used to store charge between them. One is connected with positive voltage and other one with negative voltage. A capacitor is characterized by the parameter capacitance. Capacitance is measured as ratio of difference of charges between the plates and total voltage drop between the plates.

C = dQ/dV

The unit of capacitance is FARAD.

Let’s have a closer look into the structure and how a capacitor is able to store charge.

 

 

The above image shows a simple electrolytic capacitor with two thin rods coming out from the cylindrical container. The capacitor is wrapped up using a plastic covering. This covering is done to label the capacitor. 

 

 

On removing the label, you can see a metal container adjoined with a rubber stand to hold the entire setup. 

 

 

Inside the metal case is a folded layer of dielectric in between metal plates. Next images give a clear perception of the internal structure of the capacitor.

 

 

In the above image, we can clearly see two different types of layers, folded like a swiss roll. A dielectric layer is sandwiched between two metal plates. These metal plates are used to store charge and the dielectric works as an insulator between them. These plates are folded round to minimize the size of the capacitor.

 

One plate works as cathode and another as anode.  To increase the value of a capacitor and the same time to keep the size smaller, we use electrolyte. However depending on the size and application, there are different types of electrolytes used in different ways within a capacitor.Generally, anode is soaked into liquid  electrolyte to increase the surface area of the plate as well as efficiency.

 

Unfolding these plates brings us even closer to the internal architecture of the capacitor.

 

 

Now, you can see that the plates are directly connected to the legs of capacitor and a rubber stand is used to hold these plates.

 

  

Lastly to summarize the building block of a capacitor includes a pair of metal plates, thin rods, a dielectric, a rubber stand, a metal container and a plastic covering.