As you all know Ruby is one of the most popular programming language on the web. It is recommended to install ruby 1.9.2 instead of 1.8.x I tried to install ruby from the package manager on Ubuntu, but ruby 1.9.2 is not there in the repo. So, I am going to show you how to… Read More »
System load System load is a measure of how busy the system is running the processes. Higher system load simply means more processes are running and more are waiting to be run. When coding php applications, it sometimes is useful or necessary to find the current load on the server/system. For example if you want… Read More »
Path Info Urls When using path info data , the urls of codeignitor apps or your custom mvc frameworks looks something like this example.com/index.php/controller/method/param1/param2 or example.com/controller/method/param1/param2 The path info data can be used to specify which class and method should be invoked on server application. Forward slash in parameter Sometimes it might so happen that… Read More »
Apache mod expires mod expires is an Apache module that can send additional expiry information about a server file to a browser. If the expiry date is set to a far future date, then the browser will fetch the file from its cache on next request and will not contact the server. This will speed… Read More »
When you install Ubuntu on your system, a common issue that pops up is that partitions other than the root partition are not writable by non-root users. The same thing happens when you add an extra disk drive to your system. The disk or partition can be read through file managers like Nautilus or Dolphin… Read More »
Install Xdebug Install the packages from synaptic package manager sudo apt-get install php5-dev php5-xdebug Configure php to use xdebug extension Locate the path to xdebug.so file martin@martin-dev:/$ find / -name 'xdebug.so' 2> /dev/null /usr/lib/php5/20060613/xdebug.so An alternative command to find the xdebug.so file is using dpkg and grep as follows $ dpkg -L php5-xdebug | grep… Read More »
This page http://httpd.apache.org/docs/2.2/howto/cgi.html describes how to give each user his own cg-bin directory. The following lines should be added to the Apache configuration file http.conf : <Directory /home/*/public_html/cgi-bin> Options ExecCGI SetHandler cgi-script </Directory> Along with this there are some more points to be kept in mind. If you .htaccess file has a section like this… Read More »
The PATH-INFO is the extra path data that follows the name of a script (or servlet) in the URL. Its different from query string. Here is a classic example: https://www.examples.com/index.php/some/path?a=b Now, over here we are actually invoking the script index.php only. However also providing some path-info data “/some/path”, which is then followed by the query… Read More »
In httpd.conf file the following line should be uncommented : LoadModule rewrite_module modules/mod_rewrite.so by removing the # sign before it. Then comes a section which looks like this : <Directory "C:/Apache2.2/htdocs"> # # Possible values for the Options directive are "None", "All", # or any combination of: # Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews #… Read More »
information_schema The following query will list out the foreign keys in mysql. It finds it out from the information_schema database. select concat(table_name, '.', column_name) as 'foreign key', concat(referenced_table_name, '.', referenced_column_name) as 'references' from information_schema.key_column_usage where referenced_table_name is not null; The output is a clean table listing out all foreign keys from all databases +———————–+————-+ |… Read More »
The innodb storage engine supports foreign keys in Mysql. To create foreign keys in phpmyadmin : 1. Convert both tables into innodb, if they are not already. 2. View the structure of the table which will have a foreign key. Make the referencing field an INDEX. 3. Now come back to structure view and click… Read More »
Views and mysqldump A little back I tried to backup a database from my webhost and restore it on my localhost mysql. It had a few views. The import of the sql file seemed to work fine. But on accessing the views in phpmyadmin mysql gave the error : #1449 – There is no 'projects'@'localhost'… Read More »
Gnome MDB viewer is a simple tool to open and view mdb (microsoft access database) files on Ubuntu or Linux Mint. It shows the database structure and the data in it
While creating a table a particular column / field can be made autoincrement as : CREATE TABLE students ( id INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1), name VARCHAR(24) NOT NULL, address VARCHAR(1024), CONSTRAINT primary_key PRIMARY KEY (id) ) ; The value of an autoincrement column increments automatically with… Read More »
To go back to the previous page the superglobal variable $_SERVER can be used. $_SERVER[‘HTTP_REFERER’] has the link to the previous page. So to redirect simply : // Method to go to previous page function goback() { header("Location: {$_SERVER['HTTP_REFERER']}"); exit; } goback();
The numerical system used in India differs from the Western system in terms of the placement of the thousands separator. Example : Number -> 1000000 Indian System -> 10,00,000 (Ten Lakh) Western System -> 1,000,000 (1 Million) While echoing numbers in PHP it is possible to format numbers with such separators using functions like number_format…. Read More »
Many software applications for linux are available in the form of source code which needs to be compiled. The general process to compile such software is by running the configure, make and make install commands. After the install process the files get installed in the system directories and the software can be run from the… Read More »
Ubuntu 9.04 did not detect the native resolution of my new LCD monitor which was 1440×900. Fix : 1. Get the Modeline – The first step is to get the modeline for the specific resolution and refresh rate using the gtf command. Here is a quick example: $ gtf 1440 900 75 # 1440×900 @… Read More »
Raw tcp sockets in C Raw sockets can be used to construct a packet manually inside an application. In normal sockets when any data is send over the network, the kernel of the operating system adds some headers to it like IP header and TCP header. So an application only needs to take care of… Read More »
TCP/IP 3-way handshake is done to establish a connection between a client and a server. The process is : 1. Client –SYN Packet–> Server 2. Server –SYN/ACK Packet –> Client 3. Client –ACK Packet –> Server The above 3 steps are followed to establish a connection between source and destination. SYN Flood DOS attacks involves… Read More »