I am new to Ubuntu Linux (version 13.10). I am following this tutorial to install MySQL, PHP, and Apache2.
It installed successfully, but I don't know where to write PHP files that execute when you navigate to the URL localhost/example.php.
I am looking at this link, but I am afraid that maybe it will not work and have to reinstall Ubuntu again.
As a simple Google search would have showed you, it's (by default), /var/www/.
In the Ubuntu default config, that is defined in the default virtual host, the config file for that is /etc/apache2/sites-available/default
The default location of document root is /var/www. This, assuming you haven't touched the HTTPd configuration.
By the way, if you simply need a development server for PHP scripts, you can use the one emebedded in PHP > 5.4. Just cd to the project directory and launch:
php -S localhost:8008
In a newer version should be in a different path: /var/www/html
With a series of commands you can find:
ls /etc/apache2/sites-available/
That answers with something like
000-default.conf default-ssl.conf
In this case you need the second file default-ssl.conf; with
grep -n -e "DocumentRoot" /etc/apache2/sites-available/default-ssl.conf
you can obtain:
5: DocumentRoot /var/www/html
That means you can find (and change) DocumentRoot definition in the 5-th lines of the file /etc/apache2/sites-available/default-ssl.conf.