PHP and server configuration information (phpinfo(), php.ini)

Often we need to find out as much information about the server as possible, the native `phpinfo()` function is great for this:

phpinfo();

die; // after listing the configuration, exit the script

This makes it easy to find out the installed version, extensions, libraries and much more.

See the end of this article for information about configuration and changing settings.

Finding a specific configuration section

Sometimes it is useful to list only specific information, so we can set the first parameter to specify exactly what we are interested in:

phpinfo(INFO_MODULES);

Predefined constants are used for setting:

Superglobal variable $_SERVER

We can find out quite a lot of information about the server settings directly at runtime (for example, the email to the webmaster, the current IP address of the visitor, or the currently called URL).

Listing all existing values is easy:

foreach ($_SERVER as $key => $value) {
    echo $key . ': ' . $value . '<br>';
}

Warning: Not all indexes need to exist (for example, if the script runs cron in CLI mode, the index with the page URL or the IP address of the request will not exist).

Reading specific configuration directives

Much of the configuration is stored in php.ini and is not directly accessible from PHP in the normal way. For example, the maximum upload file size.

To read the configuration directly, use the ini_get() function (note: this function may not be enabled on all servers, this is especially true for hosts).

For example, if we want to find out the maximum file size we can upload, we have to write our own implementation:

/**
 * @author Jan Barášek
 */
public static function getMaxUploadFileSize(): int
{
    $maxUpload = min(
        ini_get('post_max_size'),
        ini_get('upload_max_filesize')
    );

    if (strncmp($maxUpload, 'M', 1) === 0) {
        return (int) str_replace('M', '', $maxUpload);
    }

    return (int) $maxUpload;
}

Returns the maximum value of upload_max_filesize and post_max_size in MB.

Configuring the server and changing settings

The settings themselves are stored in the php.ini file. Its location can be easily found by using the phpinfo() function or by calling the php --ini command.

``shell

php --ini

Configuration File (php.ini) Path: /etc/php/7.1/cli Loaded Configuration File: /etc/php/7.1/cli/php.ini Scan for additional .ini files in: /etc/php/7.1/cli/conf.d Additional .ini files parsed: /etc/php/7.1/cli/conf.d/10-mysqlnd.ini, /etc/php/7.1/cli/conf.d/10-opcache.ini, /etc/php/7.1/cli/conf.d/10-pdo.ini, /etc/php/7.1/cli/conf.d/20-calendar.ini, /etc/php/7.1/cli/conf.d/20-ctype.ini, /etc/php/7.1/cli/conf.d/20-exif.ini, /etc/php/7.1/cli/conf.d/20-fileinfo.ini, /etc/php/7.1/cli/conf.d/20-ftp.ini, /etc/php/7.1/cli/conf.d/20-gd.ini, /etc/php/7.1/cli/conf.d/20-gettext.ini

Alternatively, the path can be handily parsed (works on Linux systems):

```shell
php -r "phpinfo();" | grep php.ini

Returns:

Configuration File (php.ini) Path => /etc/php/7.1/cli
Loaded Configuration File => /etc/php/7.1/cli/php.ini

Important: Usually the configuration is split into multiple files based on environment and packages, with php.ini applying globally to all of them, while for example CLI configuration applies only to CLI mode, i.e. calling a cron or Terminal command.

Configuring the upload file size limit

An example of a property that is often configured directly in php.ini is the maximum uploaded file size (the default is usually 2 MB, which is already low in 2018).

Within the configuration file this is written as follows, for example:

; Maximum allowed size for uploaded files.
upload_max_filesize = 40M

; Must be greater than or equal to upload_max_filesize
post_max_size = 40M

Midpoint indicates a comment, followed by specific configuration directives.

Jan Barášek   Více o autorovi

Autor článku pracuje jako seniorní vývojář a software architekt v Praze. Navrhuje a spravuje velké webové aplikace, které znáte a používáte. Od roku 2009 nabral bohaté zkušenosti, které tímto webem předává dál.

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