Drupal7 Installation (Ubuntu12.04) from the very beginning.

Drupal7 Installation

Step 1: LAMP installation guide
      take a tour to this link  http://www.howtoforge.com/ubuntu_lamp_for_newbies
      (Don't forget to Include /etc/phpmyadmin/apache.conf to the apache2.conf file)
      after those, apache2,php5,mysql and phpmyadmin are done. Type in localhost/phpmyadmin to check whether everything is ok.
Step 2: Download Drupal7 and Extract it to /home/xxx/www and Create new site in apache2
      in 'terminal'
      cd /etc/apache2/sites-available
      sudo cp default drupal7
      sudo nano drupal7 #here change DocumentRoot /var/www to /home/xxx/www # I download drupal and extract to /home/xxx/www
                        #change <Directory /var/www to /home/xxx/www and save
      sudo a2dissite default && sudo a2ensite drupal7 #deactive default site and enable drupal7 site in localhost:80 by default
      sudo service apache2 restart
Step 3: Create database for drupal7
      in browser, open localhost/phpmyamin and create new database named:drupal7 for site drupal7
Step 4: Configure site drupal7
      a) in home/xxx/www/drupal7/sites/default/
          copy default.settings.php to same directory as settings.php
      b) chmod before configuration
          chmod 755 ./sites/default/
          chmod 644 ./sites/default/settings.php
      c) in browser, open localhost/drupal7 and configure it step by step
          if you can read chinese, this site can help a lot: http://drupalchina.cn/content/drupal7-de-zhuang-tu-wen-jiao-cheng
Done          

Enable Clean URL

To enable Clean Url in apache2 powered drupal site,

Step 1: enable rewrite module in apache2
      sudo a2enmod rewrite
Step 2: in the sites-avaliable folder
      sudo nano drupal7 # drupal7 is the site copied from default
        # change all the properties with 'AllowOverride' from 'None' to 'All' and save
      sudo service apache2 restart
Step 3: open drupal site -> Dashboard-> Configration->Clean URLs 
        click the link in and tick the enable checkbox

Done