What Makes User-Friendly Script Installation?

Ideally the user would just download your software and start using it. Unfortunately this is not possible with web based scripts because they need to be installed on a web server and usually use a database. Fortunately people who download such script have at least some very basic technical knowledge. They don't need to be explained what is a right-click of the mouse.

Pre-Installation Checks

To avoid frustrations after installation, perform pre-installation checks of the server environment and let user know if something is wrong. It's best even not to allow them to continue if a major feature is not present. Here is for example how some of our installation screens look:

And here is how to perform such checks:

Checking PHP Version:

$php_version=phpversion();
if($php_version<5)
{
  $error=true;
  $php_error="PHP version is $php_version - too old!";
}

At the end you can decide just to highlight the error or to halt further execution if $error is true.

Checking MySQL Version:

Checking MySQL (or other database) version is harder because you have to connect to the database in order to run a version query. You can do that if you first ask for the DB login details, but it's better to have pre-installation checks as first step.

An option to check before connecting to the DB is to run a function like this (I got this code from somewhere):

// declare function
function find_SQL_Version() {
  $output = shell_exec('mysql -V');
  preg_match('@[0-9]+\.[0-9]+\.[0-9]+@', $output, $version);
  return @$version[0]?$version[0]:-1;
}

$mysql_version=find_SQL_Version();
if($mysql_version<5)
{
  if($mysql_version==-1) $mysql_error="MySQL version will be checked at the next step.";
  else $mysql_error="MySQL version is $mysql_version. Version 5 or newer is required.";
}

If the function can't execute shell_exec it returns -1. Then you can use this value to notify the user that there is no error yet because you could not check the version.

Checking Mail and other important PHP functions

Some lame PHP hosts disable mail() function in order to prevent spam. Checking whether mail() or any other more specific function is available is very simple:

if(!function_exists('mail'))
{
  $mail_error="PHP Mail function is not enabled!";
}

Check For Safe Mode

PHP safe mode is pretty boring issue to deal with. Here is how to make sure safe mode is off:

if( ini_get("safe_mode") )
{
  $error=true;
  $safe_mode_error="Please switch of PHP Safe Mode";
}

Checking if Sessions Work

Most PHP scripts use sessions or cookies to store some data. Some hosts don't have sessions or cookies configured properly. Here is a very simple way to check sessions:

$_SESSION['myscriptname_sessions_work']=1;
if(empty($_SESSION['myscriptname_sessions_work']))
{
  $error=true;
  $session_error="Sessions must be enabled!";
}

Then on the front-end (views, templates, HTML code, whatever you call it), displaying the results of your checks is pretty simple:

<?php if(empty($php_error)) echo "<span style='color:green;'>$php_version - OK!</span>";
else echo "<span style='color:red;'>$php_error</span>";?>

It's a good idea even to set a variable called $fatal_error or something like that and set it to true if any of the fatal checks return error. Then you can disable the "next step" button if $fatal_error is true. You don't want users to continue if there is a fatal error.

If there is no fatal error, you can let the user go to the next step:

Create DB Tables and Insert Required Data

This step is simple. Having the connect file in place connect to the DB and run queries to create the tables and insert any data in them. This could look like this:

// assuming you have DB established connection
// and have the resource identifier in $db_link

$q="DROP TABLE IF EXISTS `users`;";
mysqli_query($db_link,$q);

$q="CREATE TABLE `users` (
`id` bigint(20) unsigned NOT NULL auto_increment,
`username` varchar(100) NOT NULL default '',
`level` varchar(100) NOT NULL default '',
PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8";
mysqli_query($db_link,$q);

$q="INSERT INTO `users` (username, level) VAUES ('admin','admin');";
mysqli_query($db_link,$q);

Or something similar, hopefully you get the idea.