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Make Your Php Code Portable

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Martin Tsachev

Member info

User since: 27 Jun 2001

Articles written: 6

There's a lot of PHP code available for free on the net but also not all of it

can run on your system as it is. This article shows you how to distribute a setup required by your program to run.

Why should I care

People are different and they use different PHP configurations so if you want

to run a script on your system you have two choices:

  • set your global configuration to something that allows the code to run
  • set a configuration specific to the program

If you go for the first one you're in trouble if you try to run two programs which

require completely different setups. So the only choice seems to be the second one.

Well then how do I do this

There are four different ways to set a PHP configuration option:

  • through php.ini
  • through httpd.conf
  • through a .htaccess file
  • or directly in PHP code

The first and second ones are only available to the system administrator of a website

so you generally have to avoid them. Yes you may have access to those files but think

about the other people that may be using the code - do they have access to those files?

Usually not.

The third method — via a .htaccess file is available only on Apache (and maybe on the NCSA httpd, I'm not sure about that) but since Apache is the most

popular webserver that is usually not a problem. The other thing that you should know

about .htaccess files is that they may be disabled by the

webmaster. If this is the case your only chance is to use a globally included PHP file

which configures the system.

Setting the options with PHP code is the most portable way to configure

a system. The only problem is the accessible options are less than available to a

.htaccess file.

I'll go for a .htaccess file

The syntax for setting an option is:

php_value name value

php_flag name on or off


php_flag register_globals off

php_value arg_separator.output &

The example turns off register_globals and sets the value of

arg_separator.output to & which is preferred rather than the default


Note: you can also set boolean options with the php_value

directive, the string will be converted to boolean before assignment.

I'll go for PHP code

There's only one function for setting an option and it is ini_set()

it is also aliased as ini_alter().

There is also a function that restores the original value and it is ini_restore().

How to use these:

ini_set('display_errors', false);

ini_set('arg_separator.input', ';');



Note: in the first call to ini_set() you can also use

any type of variable it will be converted to boolean before setting the option.

Very nice but I don't know my configuration

I've got something for you too. This is a script that will detect common settings

that may prevent your code from executing properly on a different system.


define('boolean', 1);

define('string', 2);

define('integer', 3);

$php_ini_all = Array(

Array(string, 'arg_separator.input'),

Array(string, 'arg_separator.output'),

Array(boolean, 'display_errors'),

Array(boolean, 'display_startup_errors'),

Array(boolean, 'magic_quotes_runtime'),

Array(integer, 'error_reporting'),

Array(string, 'variables_order'),

Array(string, 'gpc_order')


$php_ini_perdir = Array(

Array(boolean, 'asp_tags'),

Array(boolean, 'magic_quotes_gpc'),

Array(string, 'output_buffering'),

Array(boolean, 'register_globals'),

Array(boolean, 'short_open_tag')




function display_php_conf() {

foreach ( $GLOBALS['php_ini_all'] as $option ) {

$value = ini_get($option[1]);

echo "ini_set('$option[1]', '$value');




function display_htaccess_conf() {

global $php_ini_all, $php_ini_perdir;

foreach ( array_merge($php_ini_all, $php_ini_perdir) as $option ) {

$value = ini_get($option[1]);

if ( $option[0] == boolean ) {

$value = $value ? 'on' : 'off';

$directive = 'php_flag';

} else {

$directive = 'php_value';


echo "$directive $option[1] $value





First we define these common options in two arrays for the different access levels,

the first one for options available to both PHP code and .htaccess files,

and the second only for .htaccess files. You may need to modify

that in case you use non-default settings for other options too.

The two function display_php_conf() and

display_htaccess_conf() print the PHP code

and .htaccess directives for your config respectively.

Show me the config


header('Content-type: text/plain');

echo "PHP settings:



echo "

.htaccess settings:




This will just call the functions defined above so you can easily copy & paste

it to a file or pipe it if you are using the CGI version of PHP.

Example output from the script

PHP settings:

ini_set('arg_separator.input', ';&');

ini_set('arg_separator.output', ';');

ini_set('display_errors', '1');

ini_set('display_startup_errors', '1');

ini_set('magic_quotes_runtime', '');

ini_set('error_reporting', '2047');

ini_set('variables_order', 'GPCS');

ini_set('gpc_order', 'GPC');

.htaccess settings:

php_value arg_separator.input ;&

php_value arg_separator.output ;

php_flag display_errors on

php_flag display_startup_errors on

php_flag magic_quotes_runtime off

php_value error_reporting 2047

php_value variables_order GPCS

php_value gpc_order GPC

php_flag asp_tags off

php_flag magic_quotes_gpc off

php_value output_buffering 4096

php_flag register_globals off

php_flag short_open_tag off

Some general considerations

The above code didn't mention track_vars even a single time

because as of PHP 4.0.3 it is always on. The example output was run on PHP 4.2.1

and ini_get() returns FALSE for track_vars as if it does

not even exist. If you have an earlier version of PHP it is recommended to set it to true

and disable register_globals for security and performance issues.

If you want to find even more information you can always count on the

PHP manual.

Martin Tsachev started using computers in 1992, programming Basic and has since then developed a great passion for them.

Nowadays he runs mtdev - a web site with highlight on PHP.

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