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.
PHP - Manual: ini_set
2024-12-23
ini_set
(PHP 4, PHP 5, PHP 7, PHP 8)
ini_set — 为一个配置选项设置值
说明
ini_set(string
$varname, string $newvalue): string设置指定配置选项的值。这个选项会在脚本运行时保持新的值，并在脚本结束时恢复。
返回值
成功时返回旧的值，失败时返回 false。
范例
示例 #1 设置一个 ini 选项
<?php
echo ini_get('display_errors');
if (!ini_get('display_errors')) {
ini_set('display_errors', '1');
}
echo ini_get('display_errors');
?>
参见
- get_cfg_var() - 获取 PHP 配置选项的值
- ini_get() - 获取一个配置选项的值
- ini_get_all() - 获取所有配置选项
- ini_restore() - 恢复配置选项的值
- 如何改变配置选项
add a note
User Contributed Notes 21 notes
nl-x ¶
7 years ago
ASchmidt at Anamera dot net ¶
4 years ago
When checking for the success of ini_set(), keep in mind that it will return the OLD value upon success - which may have been "0". Therefore you cannot just compare the return value - you have to check for "identity":
<?php
// This will NOT determine the success of ini_set(), instead
// it only tests if the old value had been equivalent to false
if ( !ini_set( 'display_errors', '1' ) )
throw new \Exception( 'Unable to set display_errors.' );
// This is the CORRECT way to determine success
if ( ini_set( 'display_errors', '1' ) === false )
throw new \Exception( 'Unable to set display_errors.' );
?>
This explains reported situations where ini_set() "always" seems to fail!
Tr909 at com dot nospam dot bigfoot ¶
20 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.
RebootConcepts.com ¶
16 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
Ron Ludwig ¶
16 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:'); ?>
sean at php dot net ¶
17 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:
http://www.zend.com/support/user_docs/ZendOptimizer/PDF/ZendOptimizer_UserGuide.pdf
miroslav AT simunic DOT de ¶
19 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.
daevid at daevid dot com ¶
15 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
<?php
ini_set('output_handler', 'mb_output_handler');
echo "\noutput_handler => " . ini_get('output_handler') . "\n";
?>
root@# ./myscript.php
output_handler => ob_gzhandler
Apparently (acording to Richard Lynch):
> TOO LATE!
> The ob_start() has already kicked in by this point.
> ob_flush() until there are no more buffers.
Nathan ¶
10 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:
<?php
ini_set("zlib.output_compression", 4096);
?>
Julien MOREAU aka PixEye ¶
5 months ago
In order to change zend.assertions or assert.exception values, try with the ini_set() function but be aware that it may fail.
Example:
<?php
$ret = @ini_set('zend.assertions', '1');
if ($ret === false) echo 'ini_set() failed before line ', __LINE__, PHP_EOL;
Er.ellison ¶
6 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 !
johnzoet at netscape dot com ¶
20 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:
<?php
if (empty($blnResult) or (!$blnResult)) {
echo "setting cannot be set";
exit;
}
?>
williamprogphp at yahoo dot com dot br ¶
8 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.
brainiac5 dot php at aimail dot de ¶
17 years ago
To find the apache php settings try something like this.
> cd /etc/apache2
> grep -r -n -i safe_mode_exec_dir *.conf
or
> 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.
klw at gmx dot at ¶
17 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.
MadJoker ¶
12 years ago
If you use gz_handler you might want to switch over to
zlib.output_compression
This can be controlled via the ini_set control.
<?php ini_set('zlib.output_compression', 'Off'); ?>
or
<?php ini_set('zlib.output_compression', 'On'); ?>
davey at its-explosive dot net ¶
19 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
w3dk ¶
7 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).
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