How to fix Apache – "Could not reliably determine the server’s fully qualified domain name, using 127.0.1.1 for ServerName" Error on Ubuntu

Just Edit the file /etc/apache2/httpd.conf

$sudo gedit /etc/apache2/httpd.conf

By Default it is blank

add the following to httpd.conf

ServerName localhost

now you can restart apache

$/etc/init.d/apache2 restart

How to build an exactly similar ubuntu installation on another computer

Here is an easy  way to  build an exactly similar  ubuntu installation on another computer.

Run
$ dpkg --get-selections >my_pakages

on the machine that you want to clone. Install a clean copy of Ubuntu on the target machine. Copy the file my_packages to the target machine.
Run the following command on the target machine.
$  sudo dpkg --set-selections < ./package_names
$  sudo apt-get -u dselect-upgrade

 Done.