The mail() function of PHP is quite robust for sending bulk emails. A SMTP server can also be directly used from the script. PHPmailer class can be used for sending emails.

Following are the steps to create a simple AD rotator script without using database in PHP:

- All the ad’s can be collected in one place and be displayed randomly.rand() function can be used for this purpose.

- In order to NOT use any database, a flat file can be used to store the ad’s.

- In order to store the Ad’s information (HTML code), a flat file say “ad.txt” can be created.

- The random number can be stored in a variable 

$result_random=rand(1, 100);

- Conditions can be checked to display the ad’s.

if($result_random<=70)

{

      echo "Display ad1";

}

Permissions in PHP are very similar to UNIX. Each file has three types of permissions – Read, write and execute. Permissions can be changed using the change mode or CHMOD command. CHMOD is followed by 3 digit number specifying the permission type. CHMOD 777 is for Read, Write and execute.

Unnecessary permissions can be stripped off using UNMASK command.

Unmask (777);

Notices, Warnings and Fatal errors are the types of errors in PHP

Notices: 

Notices represents non-critical errors, i.e. accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all but whenever required, you can change this default behavior.

Warnings: 

Warnings are more serious errors but they do not result in script termination. i.e calling include() a file which does not exist. By default, these errors are displayed to the user.

Fatal errors: 

Fatal errors are critical errors i.e. calling a non-existent function or class. These errors cause the immediate termination of the script.