(PHP 4, PHP 5, PHP 7)

ini_setSets the value of a configuration option


string ini_set ( string $varname , string $newvalue )

Sets the value of the given configuration option. The configuration option will keep this new value during the script's execution, and will be restored at the script's ending.



Not all the available options can be changed using ini_set(). There is a list of all available options in the appendix.


The new value for the option.

Return Values

Returns the old value on success, FALSE on failure.


Example #1 Setting an ini option

echo ini_get('display_errors');

if (!
ini_get('display_errors')) {


See Also

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User Contributed Notes 18 notes

Tr909 at com dot nospam dot bigfoot
16 years ago
[[[Editors note: Yes, this is very true.  Same with
register_globals, magic_quotes_gpc and others.

Many settings, although they do get set, have no influence in your script.... like upload_max_filesize will get set but uploaded files are already passed to your PHP script before the settings are changed.

Also other settings, set by ini_set(), may be to late because of this (post_max_size etc.).
beware, try settings thru php.ini or .htaccess.
4 years ago
Note that this function only works with PHP_INI_ALL options!
miroslav AT simunic DOT de
16 years ago
If it's not your server and therefore you want to hide the data in your session variables from other users, it�s very useful to set the session.save_handler in your scripts to shared memory with:

<?php ini_set('session.save_handler','mm'); ?>

Remember: You have to set it in every script that uses the session variables BEFORE "session_start()" or php won't find them.
12 years ago
set PHP_INI_PERDIR settings in a .htaccess file with 'php_flag' like this:

php_flag register_globals off
php_flag magic_quotes_gpc on
williamprogphp at yahoo dot com dot br
5 years ago
I figured out why php dont output errors such as an expected ';' on code and output a 500 error. Some server are configured to omit php errors on pages using the directive display_errors=Off;

In most cases, the server will output a 500 Internal Server Error instead of php error because of it.

To prevent this default you must set this directive directly in the php.ini file and the server will show you the php error properly. Setting ini_set('display_errors', true) on-the-fly wont work.
daevid at daevid dot com
12 years ago
Be careful with setting an output_handler, as you can't use ini_set() to change it. *sigh*

In my php.ini I have this for my web pages (and I want it):

  output_handler = ob_gzhandler

But this causes my command line scripts to not show output until the very end.

#!/usr/bin/php -q
('output_handler', 'mb_output_handler');
"\noutput_handler => " . ini_get('output_handler') . "\n";

root@# ./myscript.php
output_handler => ob_gzhandler

Apparently (acording to Richard Lynch):

> The ob_start() has already kicked in by this point.
> ob_flush() until there are no more buffers.
klw at gmx dot at
14 years ago
To change settings from .htaccess files, it is also required that the directory permissions configured in Apache allow this.

The <Directory /foo/bar> entry in httpd.conf MUST contain "AllowOverride All" or at least "AllowOverride Options" to read PHP settings from the .htaccess file.

E.g. in Fedora Core 2, the default settings for /var/www/html/ are "AllowOverride None", so changing PHP settings via .htaccess for applications installed below /var/www/html/ will not work.
3 years ago
if u receive  an Error with generic like  :
Maximum execution time of 30 seconds exceeded

if u set ini_set(max_execution_time, 300);
your problem will be solved
pls note that the 300 , is 300 seconds , which means 5 minute  you can set another value !
4 years ago
I have experienced on some systems that ini_set() will fail and return a false, when trying to set a setting that was set inside php.ini inside a per-host setting. Beware of this.
Ron Ludwig
13 years ago
When your ISP does not allow you to add the default include directories - it might be useful to extend the 'include_path' variable:

<?php ini_set('include_path',ini_get('include_path').':../includes:');  ?>
7 years ago
Careful - in some cases, when setting zlib.output_compression to "On" via ini_set, PHP won't send the Content-type header and browsers will garble the output. Set it to the desired buffer size instead, which sends the correct header:

("zlib.output_compression", 4096);
3 years ago
Whilst most boolean settings can be disabled by passing '0', 'Off' or `No' (in fact anything that is not '1', 'On' or 'Yes' - not case-sentive) to ini_set(), it should be noted that ini_get() returns the literal string as set. So if you later want to check this setting by calling ini_get() and it's been set to 'Off' (a non-empty string that evaluates to True), then you'll have to specifically check for this in a (case-insensitive) string comparison, rather than the simpler:

if (ini_get('config_setting')) { /* ... */ }

So, if you need to disable boolean settings I think it's preferable to set them to '0' (which simply evaluates to False).
davey at its-explosive dot net
15 years ago
If you set something using php_admin_value in httpd.conf it is then not possible to be set the value at runtime, even if it's NOT PHP_INI_SYSTEM.

Just an interesting note for Server admins this might come in handy to disable setting of certain things... like allow_url_fopen.

- Davey
sean at php dot net
14 years ago
While this doesn't belong in the manual, it should be useful for people looking on this page for zend_optimizer.* ini options, which are commonly installed:

Information on the "zend_optimizer.optimization_level" and "zend_optimizer.enable_loader" options is available at:
johnzoet at netscape dot com
16 years ago
[[[Editors note: Just because you're able to set something
doesn't mean it will work as expected.  Depends on the
setting.  For example. setting register_globals at
runtime will be of little use as its job has already
been completed by the time it reaches your script.

When a setting can not be changed in a user script, the return value of ini_set is "empty", not "false" as you may expect.
If you check in your script for return value is "false" the script will continue processing, although the setting has not been set.
The boolean return value is used for settings that can be changed in a script. Otherwise the empty value is returned.
To test for both error conditions use:

if (empty($blnResult) or (!$blnResult)) {
"setting cannot be set";
brainiac5 dot php at aimail dot de
14 years ago
To find the apache php settings try something like this.
> cd /etc/apache2
> grep -r -n -i  safe_mode_exec_dir *.conf
> grep -r -n -i safe_mode.*On *.conf

If you find a gererated file, obviously you need to find the source template for it, to change what's needed there.

I just wasted a sunny Sunday on searching for where the heck safe_mode_exec_dir was changed.

And yes, Local Value in phpinfo does mean 'changed between the php.ini file and here', as you would think.

If you have an automated virtual host configuration, such as confixx, php ini values can be spread across very many files.

They can be changed in apache config files, that can have any name, but usually will end on .conf, besides in .htaccess files.
9 years ago
If you use gz_handler you might want to switch over to

This can be controlled via the ini_set control.

<?php ini_set('zlib.output_compression', 'Off'); ?>


<?php ini_set('zlib.output_compression', 'On'); ?>
5 years ago
How to get xdebug var_dump to show full object/array regardless to php,ini settings:

ini_set("xdebug.var_display_max_depth", -1);
ini_set("xdebug.var_display_max_children", -1);
ini_set("xdebug.var_display_max_data", -1);
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