Author Archives: Etay Cohen-Solal

About Etay Cohen-Solal

Development Specialist, Artist and Activist
Personal Website

clojure-logo

CentOS Clojure / Leiningen / Luminus / http-kit Installation and sample tutorial

CentOS Clojure

CentOS Clojure installation and sample tutorial.
In the following post I’ll show how to install and configure Clojure on you CentOS box with sample web server example.

Also,, weI’ll use leiningen for manage the Clojure app and http-kit for deployment.

 

CentOS Clojure Installation

First, Clojure requires only Java 1.5 or greater, if you don’t have the JDK installed yet on your CentOS box please follow this instructions by ItekBlog writer – Adam to install Oracle Java on your CentOS box.

Download Clojure

Before you continue, check the Downloads page to install the latest version.

To download Clojure use:

# if you don't have wget installed - use: yum install wget
# if you don't have unzip installed - use: yum install unzip
cd /opt
wget http://repo1.maven.org/maven2/org/clojure/clojure/1.5.1/clojure-1.5.1.zip
unzip clojure-1.5.1.zip
rm clojure-1.5.1.zip

to bring up a simple read-eval-print loop (REPL) use:

cd clojure-1.5.1
java -cp clojure-1.5.1.jar clojure.main

try:

user=> (+ 1 2 3)
6
user=> (javax.swing.JOptionPane/showMessageDialog nil "Hello World")

Try Clojure Online

  • TryClojure provides a brower-based Clojure REPL
  • Himera provides a browser-baed ClojureScript REPL

Community Resources

Community volunteers maintain Getting Started documentation for a number of different tools and approaches.

 

Leiningen

Leiningen is the easiest way to use Clojure. With a focus on project automation and declarative configuration, it gets out of your way and lets you focus on your code.

Installing Lieningen

to install Lieningen you need to download the lein script place it on your $PATH (eg. ~/bin) and set it to be executable:

cd ~/bin
wget https://raw.github.com/technomancy/leiningen/stable/bin/lein
chmod a+x ~/bin/lein

you can read the tutorial by running lein help tutorial.

The tutorial is the best place to start. It does not cover learning the language itself; good Clojure documentation can be found.

Running lein help faq will get you the FAQ. Documentation for each individual task is available via lein help $TASK. You can also see the sample project.clj file containing a reference of most project settings by running lein help sample.

 

Creating a Project

Creating a new project is easy:

cd ~/
lein new app my_first_app
cd my_first_app
find .

In this example we’re using the 

1
app

 template, which is intended for an application project rather than a library. Omitting the app argument will use the default template, which is suitable for libraries.

Directory Layout

The output of the find command is:

leiningen_find

Here you’ve got your project’s README.md file, .gitignore file for you all GIT users, a src/ directory containing the code, a test/ directory, and a project.clj file which describes your project to Leiningen. The src/my_stuff/core.clj file corresponds to the my-stuff.core namespace.

Running Code

let’s start our code running:

lein run

 

centos clojure

centos clojure

 

For extended information and documentation about Leiningen and the REPL Read here.

 

FAQ: Set LEIN_ROOT to disable this warning.

leiningen_error

 

If you want to run LEIN using root, you should add to your ~/.bash_profile :

export LEIN_ROOT="Something"

rem

ember to touch the file:

. ~/.bash_profile

 

Frameworks

Luminus

Luminus is a micro-framework based on a set of lightweight libraries. It aims to provide a robust, scalable, and easy to use platform. With Luminus you can focus on developing your app the way you want without any distractions.

create a new project:

    lein new luminus myapp
    cd myapp
    lein ring server

the app is now available at 

1
localhost:3000

luminus-welcome

 

Clojure Deployment

When you’re ready to deploy your app, you have many web servers such as: nginx, http-kitimmutant, tomcat, JBossPallet, GlassFish, Jetty, Netty, Grizzly, etc.

 

using nginx

You can use nginx-clojure to run your clojure project inside of nginx server.

In Clojure web server benchmarks, this server achieved the highest performance.

20140121-14-30

read this tutorial for more information about nginx/clojure implementation.

 

using Tomcat

To install Tomcat server follow those steps.

You need to package the application as a WAR archive, to do that run:

lein ring uberwar

then simply copy the resulting myapp-0.1.0-SNAPSHOT-standalone.war to the webapps folder on Tomcat, eg:

cp target/myapp-0.1.0-SNAPSHOT-standalone.war ~/tomcat/webapps/myapp.war

Your app will now be avaliable at the context /myapp when Tomcat starts. To deploy the app at root context, simply copy it to webapp as ROOT.war.

 

HTTP Kit – HTTP client/server for Clojure

HTTP Kit is a minimalistefficientRing-compatible HTTP client/server for Clojure. It uses a event-driven architecture to support highly concurrent a/synchronous web applications. Feature a unified API for WebSocket and HTTP long polling/streaming

<div class="codecolorer-container text railscasts" style="overflow:auto;white-space:nowrap;width:555px;"><table cellspacing="0" cellpadding="0"><tbody><tr><td class="line-numbers"><div>1<br /></div></td><td><div class="text codecolorer">          [http-kit "2.1.16"] ; Add to your project.clj.</div></td></tr></tbody></table></div>

Check this great example of a websockets app with Clojure and http-kit.

 

That’s It!

 

Cheers!,

Development Specialist, Artist and Activist
Personal Website
postgresql-logo

CentOS PostgreSQL Installation Tutorial – (Centos 6.x)

CentOS PostgreSQL Installation tutorial

CentOS PostgreSQL

centos postgresql :

PostgreSQL is a powerful, open source object-relational database system.
In the following tutorial I’ll show how to install PostgreSQL on your CentOS box

 

CentOS PostgreSQL Installation

We can install PostgreSQL in (at-least) two ways:

  • Using YUM
  • Compile from source

 

Install from repository

yum install postgresql-server
this will install the package postgresql-server, also: postgresql and postgresql-libs.
centos postgresql

centos postgresql

Install from source

If you want to install the latest version of PostgreSQL you should compile from source. it’s recommended for advanced users and one may argue it’s recommended too for production.

Anyway, this article from DigitalOcean covers this area well (and more). If you want to compile using source you better move to that article. If you prefer or installed using repository (yum), continue…

 

PostgreSQL Service

if you’ll try to start PostgreSQL using the service command, you will see an error tells you must init the db first and create the db files in: /var/lib//pgsql/data

posgresqlerror

so,

to init on centos postgresql service use:

service postgresql initdb

posgreinit

This created a data folder in /var/lib/pgsql. You can’t run this command again without deleting first this folder (and all your data).

Also, when you called the initdb command above from RedHat’s init script configured permissions on the database. These configuration settings are in the pg_hba.conf file inside the data folder.

By default all permissions are ‘Ident’,

pgsql-ident

means the only user that can get in initially is user “postgres”, so if you’ll try ‘psql’ from root you’ll get error:

psql: FATAL: Ident authentication failed for user “root”

If you want to login and use postgres with other users than `postgres` you can change the permissions method in pg_hba.conf. change from ‘ident’ to ‘md5’ is recommended.

If you want to use phpPgAdmin (described later) you should change from ‘Ident’ to ‘md5’ or else it won’t login to your system.

 

Set port and Listen Addresses

If you need to change the default port (5432 by default) and Listen Addresses (localhost by default), you can set those vars inside the postgresql.conf inside /var/lib/pgsql/data folder.

#listen_addresses = 'localhost'
#port = 5432

 

Start service

and then, to start on centos postgresql service use:

service postgresql start

postgrestart

to make centos postgresql load on boot use the chkconfig command as follows:

chkconfig postgresql on

 

and That’s it!

 

What next?

 

Managing from Command line

login to postgres

As I mentioned, default setup has ident authentication means the only user that can get in initially is user “postgres”, so if you haven’t changed permissions scheme you should su to postgres before.

to start ‘psql’ as postgres:

# change user to postgres
su - postgres
# start psql manager
psql
# CTRL + D twice to exit both psql and su.

# You can also short the two commands into:
# su postgres -c psql

Add (or create) a user with permission to specific database?

Read this great tutorial.

 

PhpPgAdmin

PostgreSQL visual interface similar to phpMyAdmin? – in short, if you know phpMyAdmin and want phpPgAdmin, you need to add the EPEL repositories, Apache (yum install httpd) and then install using:

If your permissions scheme is currently ‘Ident’ you might need to change that to ‘md5’ as PhpPgAdmin requires it.

yum install phpPgAdmin

Then visit in your browser: http://localhost/phpPgAdmin

centos phppgadmin
centos phppgadmin

Remote connection

Edit /etc/httpd/conf.d/phpPgAdmin.conf if you want to allow access remotly and restart httpd (service httpd restart).

do you use pgsql, postgres, root, administrator as login or even user without password?
if you do, set the $conf[‘extra_login_security’] entry to false in your et/phpPgAdmin/config.inc.php.

 

Change default Postgres user password

If you really want to use the “postgres” role, make sure you set it up a password and $conf[‘extra_login_security’] is false.

use the command:

passwd postgres

to change the system user password and

ALTER USER Postgres WITH PASSWORD 'password';

That alters the password for within the database. To change the password inside Postgresql. there is also short code (inside psql):

\password

Which will ask from you a new password to set.

 

 

Cheers!

Development Specialist, Artist and Activist
Personal Website
ydpg17 reset

ydpg17 reset – going back to factory defaults

ydpg17 reset

ydpg17 reset – You may know this console as YinLips, Innova or whatever your country importer decides.

 

ydpg17 reset

to reset your YDPG17 android box – Start your YDPG17 games console with ‘POWER‘ + ‘M‘ buttons pressed. after the console start loading leave the power button and continue holding the M button until you’ll get into the menu.

ydpg17 reset

ydpg17 reset

 

to navigate in the menu (it may be different for your console):
use the wheel to move between options and power button to select.

Choose (3) Only format data and cache area.

 

ydpg17 reset

ydpg17 reset

ydpg17 reset

 

that’s it.. you’ve reset your ydpg17 game console back to default.

 

Cheers!,

Development Specialist, Artist and Activist
Personal Website
LuaJIT

CentOS LuaJIT Installation instructions

centos luajit installation instructions

centos luajit

centos luajit installation instructions – In the following tutorial I will show you how to install and use the LuaJIT Compiler on your CentOS box.

Before you continue you should already know what is Lua and JIT Compiler.

 

What is LuaJIT?

LuaJIT is a Just-In-Time Compiler (JIT) for the Lua programming language.

LuaJIT has been successfully used as a scripting middleware in games, appliances, network and graphics apps, numerical simulations, trading platforms and many other specialty applications. It scales from embedded devices, smartphones, desktops up to server farms. It combines high flexibility with high performance and an unmatched low memory footprint.

LuaJIT has been in continuous development since 2005. It’s widely considered to be one of the fastest dynamic language implementations. It has outperformed other dynamic languages on many cross-language benchmarks since its first release — often by a substantial margin.

LuaJIT is Copyright © 2005-2014 Mike Pall, released under the MIT open source license.

from LuaJIT website

 

Prerequisities

you need to install a package for GCC before compiling LuaJIT, you can do that by:

yum install gcc

or better, install the development tools:

yum groupinstall “Development Tools”

 

centos luajit installation instructions

Check the LuaJIT download page to check if newer version available. The next insructions are for the latest stable version currently available – LuaJIT-2.0.2

cd /opt
wget http://luajit.org/download/LuaJIT-2.0.2.tar.gz
tar -zxvf LuaJIT-2.0.2.tar.gz
cd LuaJIT-2.0.2
make && make install
# or sudo make install if you are not 'root'

Option 2: using git

OPTIONALLY, you can install LuaJIT using GIT. choose this method only if you want to be updated with the latests patches and updates and your don’t care about the risk of bugs. (NOT FOR PRODUCTION) 

cd /opt
git clone http://luajit.org/git/luajit-2.0.git
cd luajit-2.0
make && make install 
# or sudo make install if you are not 'root'
centos luajit

centos luajit

Running LuaJIT

That’s it. you have luajit installed.

consider the file ‘test.lua’:

print ("Hello, world!")

You can run (interpret) the file using

luajit test.lua

Save bytecode to test.out

luajit -b test.lua test.out
luajit test.out

more information about running luajit here.

 

 

That’s it! you have centos luajit installed.

Cheers!.

Development Specialist, Artist and Activist
Personal Website
VMWare Workstation start on boot CentOS

CentOS Gunicorn installation instructions for newbies

centos gunicorn installation instructions

centos gunicorn

centos gunicorn : In this simple tutorial I’ll explain how to install and run Gunicorn python server on your CentOS machine.

This tutorial is meant for Centos 6.4 and above but it should work on any CentOS 6.x release.

 

What is gunicorn?

From: Gunicorn – Python WSGI HTTP Server for UNIX:

Gunicorn ‘Green Unicorn’ is a Python WSGI HTTP Server for UNIX. It’s a pre-fork worker model ported from Ruby’s Unicorn project. The Gunicorn server is broadly compatible with various web frameworks, simply implemented, light on server resources, and fairly speedy.

 

Installation

Python

before you going to install the centos gunicorn server you need to insure you have the python interperter installed (it should be, as it’s installed by default on the latest CentOS releases). to check that you have python use the command:

python

command not found of course means you need to install python now.

 

Install python

first make sure your have python installed. Simple as:

yum install python

test python by typing: “python” and you should see something similar to:

python

(Ctrl+D to exit)

 

Gunicorn

Next we need to install gunicorn. for this we have (as always) several choices.

1) Using YUM. I personally don’t recommend it. I know some are happy to use the system packaging management wherever possible, but as for python I don’t think it’s the way to go.

To install gunicorn using yum:

yum install python-gunicorn

2) Using easy_install. using easy_install is a better choice for my taste to install python packages. this is how you install gunicorn using easy_install, but I recommend installing gunicorn using PIP as I will show next…

yum install python-setuptools
easy_install gunicorn

3) Using PIP: This is my RECOMMENDED way of installing gunicorn. to install PIP you actually need easy_install so the commands are:

yum install python-setuptools
easy_install pip
pip install gunicorn

Virtualenv

I can’t recommend enough to start working with virtualenv from beginning. At some point in the future, if you are going to consist with python coding, you are going to use the ‘pip update’ command to update some or all your libraries and then expect your python application to stop working.

Python libraries, as any open source library, have the freedom to sacrifice backward compatibility for new features, performance or redesign.

Virtualenv is a python virtual environment tool to ensure that your python applications will work as expected as long you don’t deliberately update some or all of the dependency libraries for that virtual environment specifically.

To install virtualenv (and virtualenvwrapper) and learn the basics read this tutorial. then create your virtual environment and install gunicorn to that environment.

# after you've install pip, virtualenv and virtualenvwrapper
mkproject myapp
workon myapp
pip install gunicorn

 

Running Gunicorn

Basic usage:

$ gunicorn [OPTIONS] APP_MODULE

so for the following myapp.py file:

# -*- coding: utf-8 -

def app(environ, start_response):
    data = 'Hello, World!\n'
    status = '200 OK'
    response_headers = [
        ('Content-type','text/plain'),
        ('Content-Length', str(len(data)))
    ]
    start_response(status, response_headers)
    return iter([data])

just run:

gunicorn -w 4 myapp:app
# Sample output
[INFO] Arbiter booted
[INFO] Listening at: http://127.0.0.1:8000
[INFO] Worker spawned (pid: 16801)
[INFO] Worker spawned (pid: 16802)
[INFO] Worker spawned (pid: 16803)
[INFO] Worker spawned (pid: 16804)
centos gunicorn

centos gunicorn

This command starts gunicorn with 4 workers on port 8000. feel free to experiment and customize the command with additional parameters.

There also command line for using Django <1.4 and Paster. read more here.

Read more about configuring Gunicorn and configuration files.

 

Deploying Gunicorn

on deployment, It’s strongly recommended to use Gunicorn behind a proxy server.

nginx

I personally prefer nginx but it’s not your only choice.

If you want to install nginx on your CentOS machine follow this installation instructions.
use this script (at github) to configure your nginx to pass request to the gunicorn process

 

Monitoring and Logging

Usally you’d want the gunicorn to be run in the background, load on boot and restart on errors. you want also the ability to monitor that process.

There are several tools for that.job, including: Supervisord, Gafferd, runit and many more…  choose what fits you best. here you have examples for monitoring gunicorn using those tools.

 

That it. enjoy playing with your centos gunicorn setup.

 

Development Specialist, Artist and Activist
Personal Website
cento tomcat

CentOS Tomcat server installation is easy!

CentOS Tomcat installation

CentOS Tomcat

centos tomcat

“Apache Tomcat is an open source software implementation of the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed under the Java Community Process.” from Tomcat homepage.

 

Prerequisities

  • CentOS 6.x (I haven’t tested this on older versions but it should probably work as well) 

Check your Java installation

before we’ll continue the installation of Tomcat, the JDK (Java Development Kit) should be installed on your CentOS machine. to check for Java support use the command:

java -version

javanotfound

if bash returns ‘command not found‘ then continue to the next step and install the JDK, else skip the step and continue to Tomcat server installation.

 

Install Java Development Kit (JDK)

To install the jdk we have 2 options:

  1. Install OpenJDK – Using YUM.
  2. Install Oracle JDK – Install manually.

I’ll explore both:

Option 1: Install Open-JDK using YUM

For beginners and testing purposes you should go with this option.

Why should I use the Oracle JDK over the OpenJDK, or vice-versa? [closed]

The command to install JDK using YUM is very simple:

yum install java

yuminstall java

  • Note: use sudo if you are not logged-in with root.
  • the command will install the latest jdk (1.7 as for this date). If you want to install older version use the full name (search using: $ yum search jdk)yum-search-jdk
    You can see you can install the 1.6 version by typing: yum install java-1.6.0

Check you have installed it right:

javafound

 

Option 2: Install JDK manually

Download your required JDK here.

Note: I can’t give you an WGET command to download, because you need to Accept License Agreement before downloading any file.

You can download and install using the RPM or the tar.gz (both with x86 or x64) on your CentOS machine:

downloadjava

 

 

In case of our CentOS we can download and install the .rpm file or the .tar.gz file.

RPM can be installed ONLY by the root.
TAR.GZ can be installed be any user on the computer.

 

Option A: Install using .rpm

make sure to uninstall older installations (if any):

rpm –e <package name>

To install the jdk using the downloaded rpm use the rpm command:

rpm –ivh jdk-7u45-linux-x64.rpm

If you just want to upgrade a package you’ve already installed use the -Uvh parameter.

rpm –Uvh jdk-7u45-linux-x64.rpm

Delete the .rpm file if you want to save disk space.

Read more about installation of Oracle Java on Centos here on ItekBlog

 

Use alternatives :

alternatives –install /usr/bin/java java /usr/java/latest/jre/bin/java 20000
alternatives –install /usr/bin/javaws javaws /usr/java/latest/jre/bin/javaws 20000

alternatives

and config your default jdk (if you have more then one) using:

using:

alternatives –config java

alternatives-config

 

Test your environment

Just as in the first step: type java -version to see if your have jdk installed.

oraclejavaversion

 

Option B: Install using tar.gz

The advantage of tar.gz installation of the JDK is that we can able to install multiple version of java if required.

The archive can be installed by anyone (not only root users), in any location that you can write to. However, only the root user can install the JDK into the system location.

You need to unpack the .tar.gz file (using tar -xzf) into the  the location where you would like the JDK to be installed.

Unpack the tarball and install the jdk:

tar zxvf jdk-7u<version>-linux-i586.tar.gz

Delete the .tar.gz file if you want to save disk space.

 

Use alternatives :

alternatives –install /usr/bin/java java /path/to/jdk1.7.0_45/bin/java 2
alternatives –config java

read more about installation of jdk in the oracle documentation.

for extended installation tutorial read this post by adam in this blog.

 

JDK 1.6 vs JDK 1.7

read more on What is the difference between jdk 1.6 and 1.7 ?

 

Environment Variables

1
JAVA_HOME

 is a 

1
environment

 variable (in Unix terminologies), or a PATH variable (in Windows terminology) you need to create to point to where Java is installed. ($JAVA_HOME/bin/java should execute the Java runtime).

Why doesn’t the Java SDK installer set JAVA_HOME?

To set it for your current session type at bash:

export JAVA_HOME=/usr/java/jdk1.7.0_05
export PATH=$PATH:$JAVA_HOME/bin

To set the JAVA_HOME permanently we need to add the commands to the ~/.bash_profile file of the user.
We can also add it /etc/profile and then source it to give to all users.

 

Test Environment Variables

use the echo command to check you’ve configured the variables:

echo $JAVA_HOME
echo $PATH

echovars

 

Installing Tomcat

After we have java installed and tested we can continue to the installation of the Tomcat server.

Download Tomcat

Since Apache Tomcat is distributed as binaries, all you have to do is to download it and start it.

Download apache-tomcat-x.x.xx.tar.gz (latest version or any) from Apache Tomcat Homepage

I’ll go with the tomcat 8 – tar.gz package.

centos tomcat

centos tomcat

and using command:

cd /usr/share
wget http://apache.spd.co.il/tomcat/tomcat-8/v8.0.0-RC10/bin/apache-tomcat-8.0.0-RC10.tar.gz

tomcat-wget

verify and extract the download using::

md5sum apache-tomcat-8.0.0-RC10.tar.gz
tar xvzf apache-tomcat-8.0.0-RC10.tar.gz

and I have a /usr/share/apache-tomcat-8.0.0-RC10 folder now.

 

Test Tomcat server

Tomcat by default start on port 8080 you can start the server now by typing at bash:

cd apache-tomcat-8.0.0-RC10
./bin/startup.sh

tomcat-start

 

Now Access the tomcat by connecting your server with a web browser on port 8080.

http://localhost:8080

tomcat

If you cannot access the above Tomcat page, make sure to stop iptables (since CentOS has iptables on by default set to block the Tomcat’s default listening port 8080).

service iptables stop

to permanently disable iptables (NOT RECOMMENDED AT ALL) use:

chkconfig iptables off

Change the Tomcat server port

Locate server.xml in {Tomcat installation folder}/conf/ which is at /usr/share/apache-tomcat-8.0.0-RC10/conf in our case

Find the following:

 <!-- Define a non-SSL HTTP/1.1 Connector on port 8180 -->
    <Connector port="8080" maxHttpHeaderSize="8192"
               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
               enableLookups="false" redirectPort="8443" acceptCount="100"
               connectionTimeout="20000" disableUploadTimeout="true" />

and change the 8080 port to your required port.

 

Start on boot

To start the tomcat service on system boot create the file /etc/init.d/tomcat8 (I am using vi /etc/init.d/tomcat8) and fill it with:

#!/bin/bash 
# description: Tomcat Start Stop Restart 
# processname: tomcat 
# chkconfig: 234 20 80 
JAVA_HOME=/usr/java/jdk1.7.0_05 
export JAVA_HOME 
PATH=$JAVA_HOME/bin:$PATH 
export PATH 
CATALINA_HOME=/usr/share/apache-tomcat-8.0.0-RC10
 
case $1 in 
start) 
sh $CATALINA_HOME/bin/startup.sh 
;; 
stop) 
sh $CATALINA_HOME/bin/shutdown.sh 
;; 
restart) 
sh $CATALINA_HOME/bin/shutdown.sh 
sh $CATALINA_HOME/bin/startup.sh 
;; 
esac 
exit 0

Now set the permissions on the file and the catalina.sh file:

chmod a+x /etc/init.d/tomcat8
chmod a+x /usr/share/apache-tomcat-8.0.0-RC10/bin/catalina.sh

to start/stop/restart the service use:

service tomcat8 start
service tomcat8 restart
service tomcat8 stop

to start the service on boot use:

chkconfig --add tomcat8
chkconfig tomcat8 on

to disable it later you can use off instead of on:

chkconfig tomcat8 off

 

 

That’s it! you have your CentOS Tomcat server working and runing… 

Development Specialist, Artist and Activist
Personal Website
ddwrt_979

DD-WRT set date manually

dd-wrt set date manually

dd-wrt set date manually – In this tutorial I’ll explain how to set the date and time in dd-wrt based routers.

 

dd-wrt set date manually

My dd-wrt system is dd-wrt v24-sp2 (11/02/09) std
(SVN revision 13064M VINT Eko).

It may not work on your system but I’ll explain the basics so you should be able to find your own way.

 

dd-wrt set date manually

in dd-wrt set date manually using command-line. you can do this by:

  • SSH to your dd-wrt machine, or
  • use the web interface to run command line

Becuase ssh is not opened by default on all dd-wrt machines I’ll explain how to set the date and time using the second method – using the web interface. but the same command and rules apply also to SSH connection.

 

Admin Panel

go to your dd-wrt admin managment panel on your browser and view the Administration / Commands page. it may be different in your system version but you should able to find quickly where the Commands page is.

dd-wrt set date

dd-wrt set date

Date

You can use the Date command inside your dd-wrt box to read and set your system time and date.

View current date (NOW)

to view your current date as configured in your dd-wrt machine use the ‘date‘ command.
Just fill the commands input box with ‘date’ and click on the ‘Run Commands‘ button.

date

dd-wrt-date

 

dd-wrt set date manually

Here it may be tricky. I’ve found several online blogs and manuals but nothing worked. to set the dd-wrt date manually I’ve succeded with the following command:

date 022720012014

Month Day Hours Minutes Year
02 27 20 01 2014

 

 

dd-wrt-set-date

 

that’s it. I hope It helped you to configure your dd-wrt set date manually.

Development Specialist, Artist and Activist
Personal Website
G-WAN

CentOS G-WAN server installation instructions

CentOS G-WAN Server

CentOS G-WAN server

G-WAN is a web server with scripts in Asm, C, C++, C#, D, Go, Java, Javascript, Lua, Objective-C, Perl, PHP, Python, Ruby and Scala.

G-WAN better uses CPU Cores
to make the Internet of Things
fly thousand times higher !

Leverage legacy servers and
low-consumption CPUs to
do more with less!

G-WAN works best on Linux distributions like Debian or CentOS, both of which offer ‘Desktop’ and ‘Server’ flavors.

 

CentOS G-WAN server installation instructions

CentOS G-WAN installation instructions

 

Installation

choose a location for your installation. for demonstration purposes we’ll install G-WAN to /opt

cd /opt
wget http://gwan.com/archives/gwan_linux64-bit.tar.bz2
tar -xjf gwan_linux64-bit.tar.bz2; cd gwan_linux64-bit
sudo ./gwan
centos g-wan

centos g-wan

use the 32bit version instead (http://gwan.com/archives/gwan_linux32-bit.tar.bz2) if you need.

Test

Then, type http://localhost:8080/ in your browser

centos g-wan

centos g-wan server default homepage

and play with the/gwan/.../csp samples.

 

Programming Languages

If you want to install more Programming Languages read the FAQ – Setup of Programming Languages

To install all 15 languages using the bash script donated by generous user on many Linux distributions (Debian, LinuxMint, CentOS, Fedora, RedHat, Manjaro, Arch Linux and Bridge) use:

cd /opt
wget http://www.as2.com/linux/tools/G-WAN_full-install.tar.bz2
tar -xjf G-WAN_full-install.tar.bz2
./G-WAN_full-install

The installation menu is available in English, German, French and Spanish!

 

Service mode

To start G-WAN as a service (make it start automatically at boot time) use this instructions

with one exception for CentOS in the manual:

instead of:

sudo update-rc.d gwan defaults 95 5

use:

sudo chkconfig gwan on

and you don’t need to restart.

 

What’s next?

check the API and Frequently Asked Questions.

Stackoverflow lists many more examples and will let you search for replies to common questions.

 

And that’s it. you have G-WAN server.

Development Specialist, Artist and Activist
Personal Website
how to speed website

How to speed up website load time

How to speed up website load time

How to speed up website load time is important question for those that performance matters to them.

Nobody Likes a Slow Website!

 

Overview

How to speed up website?

Website optimization is a required step for production, and when is automated when possible correctly it can help you deliver your website as fastest as possible without compromising on development comfortability and code readability.

 

Test your website load time speed

How to speed up website question could be answered for your case better if you’ll use a website speed test tools. There several good websites load time speed tests available online for free. check out pingdom website speed test, Google PageSpeed tools. this are very good tools which also gives you important and valuable information and tips to speed up your website.

 

pingdom

You can also check: WebPagetest, GTmetrix or PageScoring Website Speed Test.

Some of them rates your website and/or explain what could be done to make your site faster. you can learn also a lot from loading time graphs.collect information from all the above to optimize your website to maximum.

  • If it takes more then 10 seconds for your website to load. you are doing a very bad job optimizing your website (if at all).
  • If your page load time takes several seconds then you’re ok (but you can do better then that!).
  • if your page load time takes up to two seconds then your site is in very good shape!
  • if your page load time takes less then a second then your site is sooooo fast!! and you are doing a excellent job!

if your score is bad.. continue reading How to speed up website

 

How to speed up website load time

So, how to speed up your website load time?

You can do that using several tweaks.. one at a time…

 

1. learn the waterfall. where are your bottom neck ?

Use the mentioned websites speed test graphs to learn what are the slowest parts of your website and start with them. does the problem is with your webserver or maybe the infrastructure?

How to speed up website ? Does your static files load time is the problem?

And maybe it is the dns? processing request? loading the images? loading the scripts? maybe you have bad requests?

This extreme powerfull tool will help you learn your weaks and strongs.

how to speed website

how to speed website

2. Minimize redirects

If your website on load check if it’s mobile or not, then it redirect to another page when checks the language and then redirects to another page who check the cookies and then redirect… well you’ve got the idea. Bad design pattern!

Minimize redirects!

 

3. Browser caching

Set up your server to return Expire and Cache-Control headers with static files. Setup you expire date to be within week or more is a very good timeframe (depend on how frequently you update your website static files you can setup the expire date as required).

 

4. use CDN (if possible)

Content Delivery Network (CDN) can be an important tool in achieving decent page load and web application speeds. Providers such as AkamaiEdgeCast, Amazon (CloudFront), Rackspace (CloudFiles), Google (PageSpeed) and Microsoft (Azure CDN) are providing the means to distribute your content to locations geographically closer to your customers/users, which improves the responsiveness of the application or website.

 

5. put cache server between your server and your client when possible

Although using a CDN can help with page load speeds, a CDN is not always the best solution in terms of Cost–benefit.

when configuring a cache server before your website server, and no matter if it’s apache, tomcat, gunicorn or any other html generator you can boost up clients page load dramatically.

 

caching the compiled html pages is very important speed tweak. if you have any static and/or low-rate updated pages with no problem if some users will not see the lastest updates of the html when it changes (until cache reloads).. check varnish-cache or squid-cache or nginx (with HttpProxy module) or Apache with mod_proxy.

You should think of your webapp as in several seperate layers. where one layer could answering html requests and other serving your static files. always try to find the suitable tool for this mission in terms of speed (and taste). consider serving your static files (those not on CDN) using the fastest web server for static files you can find.

 

6. Minify

A very important stage is to minify data.

  • Minify CSS files for production! there are many simple gui or command tools to do that..
    if you are using LESS, SASS or other, Never compile on client side! compiler only on server side and setup your compiler to minify results.
  • Minify your JS files. if possible, insert them as scripts into the html, or better, minify and join them inside when processing the html (But don’t forget to use Cache server!).
    If you’re using Coffee-script and template engine it should be easier as you can compile the ,coffee file to minified version and include it within your template.
  • Minify HTML. if you have static html files use command or gui tool. if you have more advanced server like python or ruby – minify them before sumbit.
  • If your template engine support preprocessors. use them to minify HTML (and everything other you can). if not – use a library (if possible).

 

7. GZip

Configure you webserver (nginx, apache,etc)  to GZip response.

Set the Vary header (Vary: Accept-Encoding header) correctly for Internet Explorer.

 

8. Caching data

If you have data you can cache in memory for your application server – DO IT.

Use Redis, memcached or any other tool you find is suitable.

It can be small data (like the number of your followers you’ve just counted from facebook, twitter and youtube JSON calls) or the Entire processed HTML.

Put expire time for each resource on your store as needed.

 

 

How to speed up website

‘ How to speed up website ‘ tutorial ends here.

hope you’ll have fun optimizing your website and now you now few important tips on How to speed up website

Using those steps I’ve managed to reduced my website load time from several seconds to only 1-2 seconds (and sometimes less then second). It’s was worth the effort!!

 

Good day (or night),

Development Specialist, Artist and Activist
Personal Website
VMWare Workstation start on boot CentOS

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS

Overview

SSL handshake failed: SSL error: Key usage violation in certificate has been detected.

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS.

SSL handshake failed: SSL error: Key usage violation in certificate has been detected CentOS.

 

Fix

You may experience the issue if both of the following conditions are met:

  • VisualSVN Server has a self-signed certificate applied and
  • Subversion client is built against the GnuTLS library.

GnuTLS library is an open-source alternative to OpenSSL. Most Subversion clients for Windows are built against OpenSSL and are not affected by this issue. While some Subversion packages (available mostly on Linux-based operating systems – The subversion that comes with EL 6 is linked against GnuTLS which is a change from older releases which linked against OpenSSL) are built against GnuTLS and are affected.

The server is using an SSL cert was created with the ‘key usage’ extension, and the client is using the gnutls SSL library which doesn’t understand the extension. The solution is either to have the client use the openssl library or to have the server use a cert that doesn’t use the ‘key usage’ extension.

It’s recommended to fix the issue on your server side, but you can workaround it from the client side too.

 

Fix (Server side)

Here is what visualsvn.com say:

It’s not recommended to use a self-signed certificate in a production environment. We advise to use a certificate issued by your domain or a third-party certificate authority instead of a self-signed one.

If you have to use a self-signed certificate please follow the instruction to generate a cerificate without specifying ‘Key Usage’ extension:

Add the following registry value to the Windows registry:

for 32-bit system:

[HKEY_LOCAL_MACHINE\SOFTWARE\VisualSVN\VisualSVN Server]
“CreateGnuTLSCompatibleCertificate”=dword:00000001

for 64-bit system:

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\VisualSVN\ VisualSVN Server]
“CreateGnuTLSCompatibleCertificate”=dword:00000001

Start VisualSVN Server Manager.
Go to Action | Properties | Certificate.
Click Change certificate… and follow the wizard instructions to generate a new self-signed certificate.

The certificate will be generated without the ‘Key Usage’ extension and will be compatible both with GnuTLS and OpenSSL.

 

Fix (Client side)

The options for client side fix are:

 

That’s it.

Development Specialist, Artist and Activist
Personal Website
googlelogo

Good SEO tips – Search engine optimization for your blog posts

Good SEO tips

Good SEO tips

Good SEO tips for your website / blog / posts /  etc.

Focus Keyword

The first thing you should do BEFORE writing your post is to choose a Focus Keyword.

  • A good Focus Keyword whould be the shortest and most common google search you would like to point to your post.
  • avoid using the same keyword in your website twice.

For example: The focus keyword of this post is “Good SEO“.

You can visit google and start typing “Good SEO” and you’ll see using the auto completion tool that this keyword search is the most common Keyword.

goodseosearch

Note: you can actually use other then the most common keyword (in our example, we could use the “Good SEO Tips” keyword, and It could be a great keyword too. It depends on you to choose what you think would fit best your post and is more related to the content of your post.

I could use also “Best SEO” keyword but as you can see below, is not so common used keyword:

bestseosearch

 

REMEMBER the keyword as you will need to use it in page title/url/content/etc.

 

Writing the article

Now you can start working on your article. Make sure you following:

 

Article Heading

In our example with the keyword “Good SEO“… our heading is:
“Good SEO tips – Search engine optimization for your blog posts

  • Your article heading should contain the keyword / Phrase. better when it at the beginning which is considered to improve rankings.
  • Remember that viewable limit of the heading in search engines is: 70 characters; some words will not be visible to users if it will be longer.
  • If you choose to set a longer heading, use a SEO Title

 

SEO Title

If you used title longer then 70 characters in your CMS (Like WordPress Page Title) use the HTML <title></title> to set a maximum of 70 chars title to your page.

this page title is:
<title>Good SEO tips – Search engine optimization for your blog posts</title>

 

Page titles

  • Your page title (<h1>) should contain the Keyword similar as the article heading.
  • Also make sure you have a sub header <h2> with the keyword.

 

Page URL

  • The keyword should appear in your page URL.

for example: this page URL is:
http://itekblog.com/good-seo-tips

 

Content

  • Make sure the keyword appears in your post content at least several times (at least 6+).
  • The keyword should appear in the first paragraph of the copy.
  • Write no less then 300 words in your copy.
  • run the Flesch Reading Ease test on your article. The copy scores 75.1 which is considered fairly easy to read.
  • add at least 1 outbound link(s). (<a href=””>)

 

Images

  • Add images to your article. at least 1 or 2. insert the keyword to the Alt=””. Adding the keyword as a caption for the images would be great too. look in this example:
Good SEO Tips. This is how it should be done!

Good SEO Tips. This is how it should be done!

 

Meta Description

  • Meta Description is the <meta> tag on your html. the preview on google (and other search engines) will show the meta when available instead of showing the first 156 chars of the article (including titles).
  • Use your keyword inside the meta. Preferably at the beginning. More then once will be better.
<meta name=”description” content=”Good SEO: what is the best description for my post with the keyword inside?.”/>

This article Meta is:

First thing you should do BEFORE writing your post is to think of a good SEO plan. good SEO will help your copy to reach more visitors from search engines!.

Which is exactly 156 chars!.

 

Twitter

Support Twitter too!! Using:

<meta name=”twitter:card” content=”summary”/>
<meta name=”twitter:site” content=”@ITekBlog”/>
<meta name=”twitter:domain” content=”ITek Blog”/>
<meta name=”twitter:creator” content=”@ITekBlog”/>
<meta name=”twitter:image:src” content=”http://itekblog.com/wp-content/uploads/2013/11/googlelogo-300×146.png”/>
<meta name=”twitter:image:src” content=”http://itekblog.com/wp-content/uploads/2013/11/goodseosearch.png”/>
<meta name=”twitter:image:src” content=”http://itekblog.com/wp-content/uploads/2013/11/bestseosearch.png”/>
<meta name=”twitter:description” content=”First thing you should do BEFORE writing your post is to think of a good SEO plan. good SEO will help your copy to reach more visitors from search engines!.”/>
<meta name=”twitter:title” content=”Good SEO tips – Search engine optimization for your blog posts”/>
<meta name=”twitter:url” content=”http://itekblog.com/good-seo-tips/”/>

Google+

Add link to your Google+ page. If authenticated right you will have your image near google searches.

<link rel=”author” href=”https://plus.google.com/109370438350838521961/“/>

 

For WordPress users

If you use WordPress: “WordPress SEO by Yoast” will help you do the job right!

Development Specialist, Artist and Activist
Personal Website
facebook logo

What is the best resolution for facebook images

what is the best resolution for facebook images

what is the best resolution for facebook images

what is the best resolution for facebook images ?

Using the recommended image size resolutions and aspect ratio (proportion) on your images when you upload to facebook, guarantees that users will see your images exactly as you intended – without crops and as large (and noticable) as possible.

 

Cover

The resolution for facebook Cover image is 851 Pixel on 315 pixels (851X315 pixels).
You can scale the image in proportion (for example:1702X630).

Cover

 

This will fit exactly the facebook cover:

Facebook Cover

 

 

Group Cover

For group cover in facebook, best resolution size is: 801X250.
You can scale the image in proportion (for example:1602X500).

801X250

Again, it will fit exactly in the group cover.

group example

 

 

Post

what is the best resolution for facebook images

what is the best resolution for facebook images

When you upload a photo to facebook timeline, the best resolution would be with resolution of 359X399 pixels.
You can scale in proportion (for example:718X798 pixels).
This resolution is the maximum visible image size proportion on facebook timeline; other proportions will be cropped to fit either to the width (359) or the height (399).

This will shown in your friends/followers timeline as biggest as possible:

359X399-preview

Highlight

If you want to highlight the post – better use 843X404 aspect ratio.

 

Page’s profile

Page profile pictures are square and display at 160×160 pixels on your Page. The photo you upload must be at least 180×180 pixels. Rectangular images will be cropped to fit a square.

 

Quality Issues.

Facebook automatically resizing and formatting your photos. If you’d like to use more advanced techniques to make your photos look better, try these tips:

  • Resize your photo before you upload it.
  • If you use a 2048 px photo, make sure to select the High Quality option when you upload it.
  • To avoid compression when you upload your cover photo, make sure the file size is under 100 KB.
  • Save your image as a JPEG with an sRGB color profile.

 

Have fun.

Development Specialist, Artist and Activist
Personal Website