Saturday, December 31, 2011

Something about 'chkconfig'


chkconfig provides a simple command-line tool for maintaining the /etc/rc.d directory hierarchy by relieving system administrators of the task of directly manipulating the numerous symbolic links in those directories. Normally chkconfig will be found on Redhat Linux, Fedora and CentOS.
Chkconfig has five distinct functions which is adding new services for management, removing services from management, listing the current startup information for services, changing the startup information for services, and checking the startup state of a particular service.

Below are those examples explains how to use the chkconfig command:
1. View Current Status of Startup Services
The –list option displays all the services with the current startup configuration status.
# chkconfig --list (this will list down all services)
# chkconfig --list | grep network (this will list a service, in above example which is network service only)
2. Add a new Service to the Startup
Use –add option to add a specific service to the list of services that will be started during system reboot.

The following example shows how to add a new service.
# chkconfig --add iptables
# chkconfig --list | grep iptables (to view the new added service)
iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off (output)
3. Remove a Service From Startup List
The following example shows that ip6tables services is configured for startup.
To remove it from the startup list, use the –del option as shown below.
# chkconfig --del ip6tables
# chkconfig --list | grep ip6tables (to check removed service)
4. Turn-on or Turn-off a Service
The following example will turn off ip6tables service
# chkconfig ip6tables off
# chkconfig –level 35 ip6tables off (turn off ip6tables for both level 3 and 5)
       
        chkconfig -t|--terse [names]
       chkconfig -s|--set [name state]
       chkconfig -e|--edit [names]
       chkconfig -c|--check name [state]
       chkconfig -l|--list [--deps] [names]
       chkconfig -A|--allservices
       chkconfig -a|--add [names]
       chkconfig -d|--del [names]

Sunday, December 18, 2011

Go programming language


Do we really need another programming language? There is certainly no shortage of choices already. Between imperative languages, functional languages, object-oriented languages, dynamic languages, compiled languages, interpreted languages, and scripting languages, no developer could ever learn all of the options available today.
And yet, new languages emerge with surprising frequency. Some are designed by students or hobbyists as personal projects. Others are the products of large IT vendors. Even small and midsize companies are getting in on the action, creating languages to serve the needs of their industries. Why do people keep reinventing the wheel?
The answer is that, as powerful and versatile as the current crop of languages may be, no single syntax is ideally suited for every purpose. What's more, programming itself is constantly evolving. The rise of multicore CPUs, cloud computing, mobility, and distributed architectures have created new challenges for developers. Adding support for the latest features, paradigms, and patterns to existing languages can be difficult. Sometimes the best answer is to start from scratch.

Google has announced the launch of a new -open source- programming language which is built on C programming language and other more languages like Python.

This new language combines the speed of development from Python and the performance and security in C and C++. It has been mentioned that Go is a powerful programming language and it is suitable for systems with multiple processors due to its quick implementation of the instructions and its compatibility with PCs and servers at the same time as well as its simplicity. The official site mentioned that Go concurrency mechanisms "make it easy to write programs that get the most out of multicore and networked machines, while its novel type system enables flexible and modular program construction."

Learn Android.... free resources... on net

Android popularity has been increased and as a result, there are now many great resources for learning android developing available for free. I list some of them....

1-    Android Bootcamp Training Course ( 5 days), now free online:http://marakana.com/techtv/android_bootcamp_screencast_series.html
2-    Developing Android Applications ( from Oreilly) 3 workshops :http://training.oreilly.com/androidapps/
3-    Learn Android from Xtensivearts , 11 Episodes:http://www.xtensivearts.com/topics/tutorials/

Tuesday, December 6, 2011

web application framework

1. Django 
2. Cakephp
3. Ruby on Rails (RoR)
4. Drupal (CMS)
                Drupal is an open source Content Management System(CMS) written in PHP. It is open source social publishing software that empowers individuals, teams, and communities to easily publish, manage and organize a wide variety of content on a website. It is used as a "back end" system for many different types of websites, ranging from small personal blogs to large corporate and political sites.

Monday, December 5, 2011

Intel Core i3 vs Core i5 vs Core i7 Comparison- The Difference

This post explains the difference between the Intel Core i3, Core i5 and the Core i7 processors.

Intel Core i3
Codenamed: Clarkdale (Westmere)
Fabrication: 32 nm
Instruction set: X86, X86-64, MMX, SSE 4.2
Socket: LGA 1156
Bus: Direct Media Interface
RAM: DDR3
Chipset Support: P55, H55, H57, Q57
Intel Core i5
Codenamed: Lynnfield (Nehalem), Clarkdale (Westmere)
Fabrication: 45 nm, 32 nm
Instruction set: X86, X86-64, MMX, SSE 4.2
Socket: LGA 1156
Bus: Direct Media Interface
RAM: DDR3
Chipset Support: P55, H55, H57, Q57
Intel Core i7
Codenamed: Bloomfield (Nehalem)
Fabrication: 45 nm
Instruction set: X86, X86-64, MMX, SSE 4.2
Socket: LGA 1366
Bus: Quick Path Interconnect
RAM: DDR3
Chipset Support: X58

Intel has classified the Core processor range into Core i3, Core i5 and Core i7. Both the cost and the performance goes on increasing as you move from Core i3 to Core i7.
Intel Core i3
The Core i3 processors are dual core processors based on the Clarkdale (Westmere) architecture. They have a 32 nm fabrication and work with LGA 1156 socket motherboards. Direct Media Interface (DMI) replaces FSB in the Core i3 processors, unlike the faster Quick Path Interconnect in the Core i7 processors. They have clock speeds ranging from 2.93 to 3.06 GHz. They have 2×256 KB L2 cache and 4 MB L3 cache. They are compatible with these chipsets – P55, H55, H57, Q57. They don’t support Turbo Boost (dynamic overclocking) unlike the Core i5 and Core i7. They also have an Integrated graphics processor. They also have Hyperthreading support.
Intel Core i5
There are two types in Core i5 – Dual core and Quad Core. The dualcore Intel Core i5 processors are similar to the Core i3s while the quadcore Core i5s are much closer to the Core i7 in terms of features.
DualCore Core i5 Processors – They are based on the Clarkdale (Westmere) architecture like the Core i3. They also have a 32 nm fabrication and work with LGA 1156 socket motherboards. Direct Media Interface (DMI) replaces FSB in the Core i5 dualcore processors. They have clock speeds ranging from 3.2 to 3.6 GHz. They have 2×256 KB L2 cache and 4 MB L3 cache. They are compatible with these chipsets – P55, H55, H57, Q57. They support Turbo Boost (dynamic overclocking). They also have an Integrated graphics processor and also include Turbo Boost (dynamic overclocking). They also have Hyperthreading support.
QuadCore Core i5 Processors – They are based on the Lynnfield (Nehalem) architecture similar to the Core i7. They have a 45 nm fabrication and work with LGA 1156 socket motherboards. Direct Media Interface (DMI) replaces FSB in the Core i5 quadcore processors. There are 2 processors with clock speeds of 2.4 and 2.66 GHz. They have 4×256 KB L2 cache and 8 MB L3 cache. They are compatible with these chipsets – P55, H55, H57, Q57. They do support Turbo Boost (dynamic overclocking). However they don’t support Hyperthreading and don’t have a Integrated Graphics Processor.
Intel Core i7
They are the most powerful of the lot. They are based on the Bloomfield (Nehalem) architecture. They have a 45 nm fabrication and work with LGA 1366 socket motherboards. They have Quick Path Interconnect (QPI) which is faster than both DMI in Core i3/i5 and FSB. They are native quad cores which offer the best performance. They have 4×256 KB L2 cache and 8 MB L3 cache. They are compatible with the X58 chipset. They support Turbo Boost (dynamic overclocking) and Hyperthreading (8 virtual cores). However they don’t have an Integrated Graphics Processor.