Friday, August 5, 2011

Eclipse color theme

Download eclipse color theme plugin for easy installation of several color themes for your Eclipse IDE.

If you are on Eclipse 3.6 (Helios), the easiest way to install the plugin is from the Eclipse Marketplace. Go to Help→Eclipse Marketplace..., then search for Eclipse Color Theme and install it.

If you are on Eclipse 3.5 (Galileo), go to Help→Install New Software..., press Add Site and enterEclipse Color Theme as the name and as the URL. Then select the new entry from the select box labeled Work with, mark Eclipse Color Theme for installation and proceed.

After the installation, go to Window→Preferences→General→Appereance→Color Theme to change the color theme.

Saturday, July 30, 2011

Mac: Take a screenshot in different ways

In Mac OS X, there are 3 ways to take a screenshot.

1. Cmd+Shift+3 : Capture the entire screen.

2. Cmd+Shift+4 : Capture a selected area of your screen. The cursor will turn into a crosshair and you can drag around the area you want to capture.

3. Cmd+Shift+4+Spacebar : Capture a specific window or Dock or menu bar. The crosshair will turn into a little camera and highlight the window or objects you can capture. Left Click to capture.
You can use Expose shortcut to switch between windows. After you switch press alt or cmd key to get the little camera. Left Click to capture.

Monday, July 18, 2011

jQuery: get specific list item by id

Consider the following html snippet

<div id="fruits">  
           <li id="5">Apples</li>  
           <li id="29">Oranges</li>  
           <li id="32">Peaches</li>  
           <li id="47">Bananas</li>  
           <li id="30">Grapes</li>  

You can get a specific list item using jQuery
 $jq("#fruits ul li[id=32]");  

Thursday, July 14, 2011

Mac: Mac OS X 10.6.8 Printing Issue, and a Fix

With the recent update to Mac OS X 10.6.8, the printing does not work.
After updating to 10.6.8, you might be Getting “paused printer” message

Download Fix Here

For More details, View This Post 

Tuesday, June 21, 2011

Unix: Get total size of mutliple folders or files

The following command gives the total size of the folders you have selected at the end of the list.
 $ du -sch foo/ dummy/ data/ booger/  
 3G     foo/  
 2G     dummy/  
 9G     data/  
 5G     booger/  
 19G    total  

Saturday, April 30, 2011

MySQL: Resetting auto-increment value of a table

During development, usually we want to delete records from the table manually, then the tables auto-increment column remains where it was. We might want to reset the auto-increment value for the table.

For example, if you delete records with id's 7,8,9
Now when you insert through application, it inserts the new record starting at 10. But we want it to start at 7.

Use the following SQL to reset to a specific value

If you want to delete all records from your table and restart auto-index at 1, then

Tuesday, April 26, 2011

MySQL: Calculate DATE, TIME difference in SQL statement using MySQL DB

Following examples showing how to calculated DATE, TIME differences in SQL statement in MySQL database.

Functions used in the following examples are TIMEDIFF and DATEDIFF

 select TIMEDIFF('2011-10-31 12:50:56' , '2011-09-23 12:50:21')   
 The above outputs : 838:59:59  
 select TIMEDIFF('15:50:56' , '12:55:21')   
 The above SQL outputs: 02:55:35  
 select DATEDIFF('2011-10-31 12:50:56' , '2011-09-23 12:50:21')   
 The above SQL outputs: 38  
 select DATEDIFF('2011-10-31' , '2011-09-23')   
 The above SQL outputs: 38  

Sunday, April 24, 2011

JAVA: Read and Write PPM, PGM images in JAVA

Download the code library from HERE
Also you can download some sample PPM and PGM images from here.

The following helps to setup the project using Eclipse.
This requires 2 Image Processing libraries which are included in the zip. [jai_imageio.jar and clibwrapper_jiio.jar]
If you are not using eclipse, please add these 2 libraries to your project.

After opening Eclipse:

1. Goto File->New->Java Project
2. In the "contents" section, select the radio button "create project from existing source"
3. Click browse to point to the downloaded ImgProcTool folder (Assuming u have unzipped the file)
4. Click Finish on the "new Java Project" window.

A simple sample program is included, which reads and writes a sample PGM image.
 public class IpToolTester {  
     public static void main(String[] args) {  
           ImageTool imageTool = new ImageTool();  
           String srcPath = "lena_384.pgm";  
           Image srcImg = new Image(srcPath);  
           Image tgtImg = new Image();  
           tgtImg.init(srcImg.getNumRows(), srcImg.getNumCols());  
           imageTool.copyImg(srcImg, tgtImg);  
5. Right click on the project and select "Run as->java application"
6. If everything is fine, there will be console output ending with "Done".
7. Refresh the project, you will see a new .pgm file "lena_write.pgm".

Wednesday, April 20, 2011

Mac: Installing OOMMF on Mac OS X Snow Leopard 10.6

Mac OS have TCL/TK already installed.
So it is very easy to install OOMMF(Object Oriented MicroMagnetic Framework)

The following steps installs OOMMF at directory ~/apps/oommf12a4pre-20091216

First you need to download the oommf SOURCE code.
Here is the link to download 1.2a4pre snapshots :

Once you have downloaded untar to ~/apps/ using the following command in the terminal.
gunzip -c oommf12a4_20040908.tar.gz | tar xvf -

To Install:
Open Terminal and goto to the folder where you untarred.
 $ cd ~/apps/oommf12a4pre-20091216  
Run the following 2 commands
 $ tclsh oommf.tcl +platform
The above command prints summary of your platform configuration. Make sure all the config files are located and listed. Example output will be like the following
 oommf.tcl info:  
 OOMMF release, snapshot 2009.12.16  
 Platform Name:          darwin  
 Tcl name for OS:     Darwin 10.7.0  
 C++ compiler:          /usr/bin/g++   
 Tcl configuration file:     /usr/lib/  
 tclsh:               /usr/bin/tclsh8.5  
 Tcl release:          8.5.7 (config)     8.5.7 (running)  
 Tk configuration file:     /usr/lib/  
 wish:               /usr/bin/wish8.5  
 Tk release:          8.5.7 (config)     8.5.7 (running)  
 Tcl threads:          Yes  
 OOMMF threads:          Yes  
  Default thread count:     2  
Now you have all the configurations good, to compile and build run the following command
 $ tclsh oommf.tcl pimake  
The above command runs for a while. If there is an error, it prints the error on the console.
To launch the application
 $ tclsh oommf.tcl  

Thursday, April 14, 2011

Mac: Set Up Apache Virtual Hosts on Mac OS X Snow Leopard 10.6

There 3 simple steps to set Up Apache Virtual Hosts on Mac OS X Snow Leopard (10.6.x)
If you dont have time or lazy to follow these 3 simple steps, you can use a script

Step A:
 1. Open httpd.conf located at /private/etc/apache2/httpd.conf  
Open it using "vi" in terminal or open it using "text wrangler". Donot open using any word processing program, they will add unwanted characters into the file.

2. Find the line #Include /private/etc/apache2/extra/httpd-vhosts.conf
Remove the "#" at the beginning.Now it must look like
 # Virtual hosts
Include /private/etc/apache2/extra/httpd-vhosts.conf  

Step B:
1. Open httpd-vhosts.conf located at
Open it using "vi" in terminal or open it using "text wrangler". Donot open using any word processing program, they will add unwanted characters into the file.

2. There will be 2 existing dummy examples, you could modify one of to suit your needs. For example I modified to as:
 <VirtualHost *:80>  
   DocumentRoot "/Library/WebServer/Documents/mydemo"  
   ServerName mydemo.local  
   ErrorLog "/private/var/log/apache2/mydemo.local-error_log"  
   CustomLog "/private/var/log/apache2/mydemo.local-access_log" common  

 1. Open hosts located at /private/etc/hosts  
Open it using "vi" in terminal or open it using "text wrangler". Donot open using any word processing program, they will add unwanted characters into the file.

2. Add a new line to specify your new virtual host. For example, I added the following line  mydemo.local

Final STEP D:
1. Save all the edited files : httpd.conf, httpd-vhosts.conf, hosts
2. Restart Apache web server: System Preferences > Sharing > Web Sharing, uncheck and check web sharing
3. DONE ! Your virtual host is ready to use.

Wednesday, April 13, 2011

XML: Simple internal DTD definition example

Best way to validate is using any browser. Open the XML file in any browser.
Also, if you open in Eclipse, you can right click on the .xml file and select "validate".

 <?xml version="1.0"?>  
 <!DOCTYPE notes [  
  <!ELEMENT notes  (note*)>  
  <!ELEMENT note  (to,from,heading,body*)>  
  <!ELEMENT to   (#PCDATA)>  
  <!ELEMENT from  (#PCDATA)>  
  <!ELEMENT heading (#PCDATA)>  
  <!ELEMENT body  (#PCDATA)>  
           <body>this is msg</body>  

Monday, April 11, 2011

PHP: startsWith endsWith functions

function startsWith($needle, $haystack){  
    return preg_match('/^'.preg_quote($needle)."/", $haystack);  

function endsWith($needle, $haystack){  
    return preg_match("/".preg_quote($needle) .'$/', $haystack);  

Monday, March 28, 2011

Mac: Cool Expose Shortcuts/Features in Snow Leopard

Cool Features of Expose in Mac OSX Snow Leopard
With all windows visible (press Expose key [F3] or swipe 4 fingers down on Mac Books).
  • press Command-1 to arrange the windows by name.
  • press Command-2 to arrange windows by application.
  • Press the Tab key to view all windows belonging to one application. Press Tab again to switch between applications while remaining in Expose. You can also click an icon in the dock.
  • Hover your mouse pointer over a window and press the spacebar to view a larger Quick Look version of that window.
  • if you mouse over a window in Expose view , that window will have a blue border. When it does, press the spacebar. That window will now grow to full size -- while still within the Expose view! Now, if you move your mouse over an other window that one will grow to full size while the previous one reverts.

Friday, March 25, 2011

PHP: exec command not working; sh: command not found

When using PHP exec command, if you find sh: Command not found , error in your web server logs, you have to export the full path of that command.

Assuming, that command in /opt/local/bin, change the command to
 $cmd ='export PATH=$PATH:/opt/local/bin; myCommand 2>&1';  
 echo exec($cmd,$out);  

To debug PHP exec command, Read this

For example:
For the PHP code:
 $cmd = "gmake";  
 echo exec($cmd,$out);  

There will be no output. In your web server error log, your will have :
 sh: gmake: command not found  
To fix this, we need to export the PATH of the gmake.

Go to your terminal, find where your command is located, In this example:
 $ which gmake  

So, modify you PHP code as following:
 $cmd ='export PATH=$PATH:/opt/local/bin; gmake 2>&1';  
 echo exec($cmd,$out) ;

This will output, on your web page
 gmake: *** No targets specified and no makefile found. Stop.  

PHP: exec command not working; debugging exec command

While using PHP exec command, if it is not working , Follow these to debug

1. Check your web server error_log.
Usually in MAC, for APACHE web server, it is located at /var/log/apache2/
1.1 Case1: the web server does not have permission to read/execute a command/file.
Solution to Case1: Simple, change file permissions.

1.2 Case2: The exec command will throw sh: Command Not found
Solution to Case2: Read this

2. Append 2>&1 to your command to get std errors as well. Read this for more info

Thursday, March 24, 2011

PHP: Today, Yesterday, Tomorrow dates

In PHP, we can generate Today, Yesterday, Tomorrow Dates the following way:
 $today = date('Y-m-d');  
 $tomorrow = date('Y-m-d', strtotime('tomorrow'));  
 $yesterday = date('Y-m-d', strtotime('yesterday'));  

Monday, March 21, 2011

MySQL: Make a copy of an existing table in MySQL

We can create a copy of an existing table using the following SQL statements.
 CREATE TABLE booger_copy LIKE testing.booger;  
 INSERT booger_copy SELECT * FROM testing.booger;  
If you want to copy only half of the existing table then, you can use LIMIT keyword in the select Query

Mac: Running 32-bit JVM on Mac OSX using eclipse

I had to use SMILE API on 64-bit Mac OSX machine.
SMILE API provides 32-bit version of their binaries.

I found a way to use 32-bit JVM in Mac OSX 64bit machines using Eclipse.
By default Mac OSX comes with both 32 bit and 64bit JVM installed.
Eclipse uses 64-bit JVM by default.

In order to use the 32-bit JVM, do the following in Eclipse
1. Right Click on your project, goto "Run As", Select "Run Configurations"
2. Select the Arguments tab,
3. Add “-d32″ in VM arguments field.

Saturday, March 19, 2011

Using Filezilla to login into Amazon EC2 instance and transfer files

We can login into Amazon EC2 instance using Filezilla FTP client for simple transfers of local files.
Following are the steps:

1. Download and install Filezilla client.
2. Goto Filezilla settings(Windows) or Filezlla preferences (MAC)
3. Click on SFTP, on right side, click on add key file.

4. Select your .pem file. It will prompt you to convert into PPK file.

5. Click ok to close the settings/preferences window.
6. Open site manager, create a new site as show in the image below.
Host: your AMI address
ServerType: SFTP
Logon Tpe: Normal
User: ec2-user
No password required ! Filezilla will read through the keys and find the right key for the user/server pair that you are connecting to.

Friday, March 18, 2011

Using cURLpp software

To use the curlpp, we need to first install.

Download the package at

The simplest way to compile this package is:

  1. `cd' to the directory containing the package's source code and type

  2. Type `make' to compile the package.

  3. Type `make install' to install, if error occurs do 'sudo make install'

  4. You can remove the program binaries and object files from the
     source code directory by typing `make clean'.

After installing, there are several examples at
cURLpp is a C++ wrapper for libcURL.
libcURL is described as:
a free and easy-to-use client-side URL transfer library, supporting FTPFTPSHTTPHTTPSGOPHERTELNETDICTFILE and LDAP. libcurl supports HTTPScertificates, HTTP POSTHTTP PUTFTP uploading, kerberos, HTTP form based upload, proxies, cookies, user+password authentication, file transfer resume, http proxy tunneling and more!

PHP: exec command to get std errors

By appending 2>&1 at the end of the command will redirect errors from stderr to stdout.
If you run a simple command like cc at the command prompt, you would get the output as following
 $ cc  
 i686-apple-darwin10-gcc-4.2.1: no input files  
If u run the same command using PHP exec command
 $cmd = "cc";  
The output would be and empty array:
 Array ( )  
So, In order to get the error string as well, we need to append 2>&1
 $cmd = "cc 2>&1";  
The output will print:
 Array ( [0] => i686-apple-darwin10-gcc-4.2.1: no input files )  

Mac: location of Apache web server logs

The following location contains error_log for apache web server in Mac machines

Sunday, February 6, 2011

Mac: Flush DNS cache in Snow Leapord

Run the following command in the terminal
sudo dscacheutil -flushcache

For Windows:
ipconfig /flushdns

Saturday, February 5, 2011

HTML: Open link in a new window

The key to use is target="_blank"

 <a  target="_blank" href="">
My Blog

Friday, February 4, 2011

MySQL : Sort by Date and Time together when there are in different columns

Suppose you have date and time in two different columns of your table.
We can sort date and time together by using the ADDTIME function.
 select * from mytable ORDER BY ADDTIME(mydate, mytime);  

You can also use the ADDTIME in the select clause to get data and time together.
 select ADDTIME(mydate, mytime), city from mytable  

jQuery : Scroll to top/bottom of a specific DIV

Scroll to the bottom of the div:
         scrollTop: $jq('#divWithOverflowAuto')[0].scrollHeight}  
Or you can use:
   scrollTop: $jq('#divWithOverflowAuto').attr('scrollHeight')}  

Scroll to the top of the div:

         scrollTop: 0 }  

Wednesday, January 19, 2011

Matlab: Vector product, multiply 2 column matrices, "element-wise" multiplication

If we have 2 column matrices A, B.
>>A = [10;20;30]
A =

>> B = [1;2;3]
B =

>> A+B
ans =

>> A*B
??? Error using ==> mtimes
Inner matrix dimensions must agree.

In order to perform "element-wise" operations, we have to use ".", so for multiplication ".*", division "./"

>> A.*B
ans =

>> A./B
ans =

CakePHP : Error: The requested address “/” was not found on this server

I was moving my cakephp application to a new server and had this issue: Error: The requested address “/” was not found on this server.

The following keys might resolve your issue:

1. Check your DATABASE_CONFIG (/app/config/database.php)
2. Delete all the cache files from all of your tmp subfolders (/app/tmp)
3. Make sure your /app/tmp folder (and all of its sub folders) are writable

If you still have issues with the app, you might have to change the debug switch to 2 or 3 in the /app/config/core.php

Find the line which says "Configure::write" and replace with the following:
Configure::write('debug', 3);

This would spit all the errors on your webpage. You can debug from there.

Mac: removing known hosts/ ssh-rsa keys /RSA key fingerprint.

1. Open known_hosts file located at  /Users/username/.ssh/known_hosts or ~/.ssh/known_hosts
2. Delete the CONTENTS of the file.

Since .ssh is a hidden folder, you can show/hide hidden folders using directions at mac-showhide-files-in-mac

Tuesday, January 18, 2011

Kernighan’s Law !

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it."

Comparing Intel Core i3, i5, i7 processors

Intel Core i3
• Dual Core processor
• Hyper Threading Support (HT)
• Due to HT, this has 2 virtual cores.
2 physical cores, 2 virtual cores
• Turbo Boost (dynamic overclocking)
• Integrated graphics processor
• Fabrication : 32nm technology

Intel Core i5 – Dual Core
• Dual Core Processor
• Hyper Threading Support (HT)
• Due to HT, this has 2 virtual cores.
2 physical cores, 2 virtual cores
• Turbo Boost (dynamic overclocking)
• Integrated graphics processor
• Fabrication : 32nm technology

Intel Core i5 – Quad Core
• Quad Core Processor
4 physical cores.
• Turbo Boost (dynamic overclocking)
• Fabrication : 45nm technology

Intel Core i7
• Quad Core Processor
• Hyper Threading Support (HT)
• Due to HT, this has 8 virtual cores
4 physical cores, 8 virtual cores
• Turbo Boost Technology
• Fabrication : 45nm technology

Intel Core i7-980X and i7-970 have 6 physical cores and 12 virtual cores.

Monday, January 10, 2011

CakePHP: Multiple Inserts - Insert multiple rows using single statement.

Using the method saveAll(), we can achieve the desired goal.

If you want to save multiple records/rows into the same table.

$multipleRowData = Array(   
 Array('name' => 'Bob', 'phone' => "123-123-7777"),  
 Array('name' => 'Ann', 'phone' => "987-123-5555"),  
 Array('name' => 'Tom', 'phone' => "788-123-4569")  

This would result in inserting 3 rows in the "mymodelname" table.

Sunday, January 2, 2011

CakePHP: Adding/deleting columns in the database after the application is Baked

If you had already baked the application and now if you made changes to the database by adding or deleting columns, then do the following:

1. Open "core.php" located at : app/config/core.php
2. Find the line which looks like: Configure::write('debug', 0);
3. Change it to Configure::write('debug', 2);
4. Refresh your application webpage.
5. Reset the line in core.php to Configure::write('debug', 0);

What basically this will do is refreshing the "model" cache.
Changing the debug level will ensure that all your databases changes are reloaded.

Following are the notes related to which debug level, you want to set.
* CakePHP Debug Level:
* Production Mode:
* 0: No error messages, errors, or warnings shown. Flash messages redirect.
* Development Mode:
* 1: Errors and warnings shown, model caches refreshed, flash messages halted.
* 2: As in 1, but also with full debug messages and SQL output.
* 3: As in 2, but also with full controller dump. (NOTE: Not in CakePHP 1.3)
* In production mode, flash messages redirect after a time interval.
* In development mode, you need to click the flash message to continue.

jQuery: Count number of visible divs


If we need for a specific 'class', then

 $(".myclass div:visible").length  
 $(".myclass div:visible").size()