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PHP Manual

## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Network Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
define_syslog_variables | "0" | PHP_INI_ALL | Deprecated in PHP 5.3.0. Removed in PHP 5.4.0.

For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

`define_syslog_variables` boolean

  Whether or not to define the various syslog variables (e.g. $LOG_PID, $LOG_CRON, etc.). Turning it off is a good idea performance-wise. At runtime, you can define these variables by calling define_syslog_variables().

Installation
Resource Types
Installing/Configuring
PHP Manual