Installing VNCserver in centOS 6.4

1.    Installing GNOME Desktop

Install a window manager in order to get a full-featured GUI desktop

[root@localhost ~] #yum groupinstall "X Window System" "Desktop"

2.    Installing TightVNC Server

For CentOS 6, the server is: tigervnc-server not:  vnc-server

[root@localhost ~] #yum install tigervnc-server

3.    Create a user and a vnc login

[root@localhost ~]# useradd tom 

[root@ localhost ~]# passwd tom 

Changing password for user tom  . 

New password: 

Retype new password: 

passwd: all authentication tokens updated successfully. 

4.    Login to new user and set vnc password

[root@localhost ~]# su - tom

[tom@localhost ~]$ vncpasswd 

Password: 

Verify: 

[tom@localhost ~]$ ls .vnc

passwd

[tom@localhost ~]$ exit

logout

5.    Start vnc

Create Xstartup Script by starting the vncserver

[root@localhost ~]#  service vncserver start

Starting VNC server: 1:tom

New 'localhost.localdomain:1 (tom)' desktop is localhost.localdomain:1

Starting applications specified in /home/tom/.vnc/xstartup

Log file is /home/tom/.vnc/localhost.localdomain:1.log 

[root@localhost ~]# su -l tom

[tom@localhost ~]$ ls .vnc

localhost.localdomain:1.log  localhost.localdomain:1.pid  passwd  xstartup

[tom@localhost ~]$ exit

logout

6.    Edit the server configuration file

Edit /etc/sysconfig/vncservers, and add the following to the end of the file.

VNCSERVERS="1:tom"

VNCSERVERARGS[1]="-geometry 1024x768"

For multiple users repeat the steps 3 to 5 and add the user to the VNCSERVERS list and add a VNCSERVERARGS[x] entry.

So for two users:

VNCSERVERS="1:tom 2:john" 

VNCSERVERARGS[1]="-geometry 1024x768" 

VNCSERVERARGS[2]="-geometry 640x480" 

7.    Open the port by editing the iptables

stop iptables

[root@localhost ~]# service iptables stop

open /etc/sysconfig/iptables

add the below lines before COMMIT

-A INPUT -p tcp -m state --state NEW -m tcp -m multiport --dports 5901:5910,6001:6010 -j ACCEPT

start iptables

root@localhost ~]# service iptables start

Install Vnc Viewer for remote accessing the desktop

1.    Download VNC Client

Now go to your Windows or Linux machine and download VNC Viewer client and install in your system to access the centos server desktop.

Download vnc viewer

2.    Connect to Remote Desktop(centos server) Using Client

After you installed the VNC Viewer client, open it you’ll get similar to below screen. Enter VNC Server IP address( IP address of centos server in which vncserver is installed) along with VNC ID (i.e 1) for user tom.

Uninstalling vncserver

[root@localhost ~]# service vncserver stop

[root@localhost~]#yum remove tigervnc-server

localhost is not working in Xampp after updating Avast

Open Avast
1) Go to "Settings"
2) Go to "Troubleshooting"
3) Expand "Redirect Settings"
4) Under "WEB" look for ignored address
5) Add localhost
6) Open browser and visit your localhost page.

Keep checkbox checked after submit refresh in PHP

Below code maintain checkbox value when user click preview button


<?php
    if (isset($_POST['number']))
    {
        foreach ($_POST['number'] as $selectednumber)
            $selected[$selectednumber] = "checked";
    }
?>

<form action="" method="post">
    <input type="checkbox" name="number[]" <?php echo $selected['one'] ?> value="one" />one<br />
    <input type="checkbox" name="number[]" <?php echo $selected['two'] ?> value="two" />two<br />
    <input type="checkbox" name="number[]" <?php echo $selected['three'] ?> value="three" />three<br />
    <input type="checkbox" name="number[]" <?php echo $selected['four'] ?> value="four" />four<br />

<input type="submit" name="Submit" value="Preview" />
</form>

How to get previous page url in PHP

$realname = basename($_SERVER['HTTP_REFERER'], ".php");

Multiple submit button in a single form in PHP

<form method="post">
<input type="submit" name="save" value="Submit 1">
<input type="submit" name="cancel" value="Submit 2">
</form>


<?php
if (isset($_POST['save'])) {
  // code
}
else if (isset($_POST['cancel'])) {
  // code
}
?>

Installing the Java Plugin for Firefox on CentOS

The OpenJDK bundled with CentOS is missing a java plugin for Firefox. A simple method of getting Java to run inside the webbrowser and to run java applications is to install icedtea-web

Open a terminal and type the below command

yum install icedtea-web

Then restart your browser
Click Tools- >Add-ons
The Add-ons Manager tab will open.
In the Add-ons Manager tab, select Plugins
Click icedtea-web plugin to select it and click on the Enable button

The java verification applet (http://www.javatester.org/version.html) works fine.

Installing and configuring Java in cent OS

Most of the Linux operating systems comes with pre-installed OpenJDK package to run java-based applications and plugins.But in certain cases we need Sun/Oracle Java program to compile and run
particular development applications.

1. Download java from  
http://www.oracle.com/technetwork/java/javase/downloads/index.html

2. install java using rpm -uvh
   ## Install Java on 32-Bit OS ##
   # rpm -Uvh jdk-7u45-linux-i586.rpm
   # rpm -Uvh jdk-7u45-linux-i586.rpm

   ## Install Java on 64-Bit OS ##
   # rpm -Uvh jdk-7u45-linux-x64.rpm
   # rpm -Uvh jdk-7u45-linux-x64.rpm

3. check java installed
   # java -version

   output should be
   java version "1.7.0_45"

4. Setting up java environment variables
The easiest way to set an environment variable in CentOS is to use export as in

$> export JAVA_HOME=/usr/java/jdk.1.7.0_45

$> export PATH=$PATH:$JAVA_HOME

However, variables will disappear the moment you exit the shell. Obviously this is not helpful when setting environment variables that need to persist even when the system reboots.In such cases, you need to set the variables within the system wide profile. In CentOS , the folder /etc/profile.d/ is the recommended place to add  customizations to the system profile.

5. Create a new file called java.sh
vim /etc/profile.d/java.sh

6. Copy paste the below content in java.sh

export JRE_HOME=/usr/java/jdk.1.7.0_45/jre
export PATH=$PATH:$JRE_HOME/bin
export JAVA_HOME=/usr/java/jdk.1.7.0_45
export JAVA_PATH=$JAVA_HOME
export PATH=$PATH:$JAVA_HOME/bin

7.  If you want to load the environment variables within java.sh without having  to restart the machine, you can use the source command as in:
   $> source java.sh