PHP Server Environment Variable $_ENV_PHP Tutorial

PHP $_ENV variable

$_ENV is an array containing server-side environment variables. It is a super global variable in PHP and we can directly access it anywhere in the PHP program.

$_ENV just passively accepts server-side environment variables and converts them into array elements. You can try printing it directly:

print_r($_ENV);

Due to space limitations, the printed results are not listed here, and the printed results on different servers may be completely different.

$_ENV array element

The elements (array units) in the $_ENV array vary greatly depending on the server environment, so it is impossible to list a complete list like $_SERVER. The following are the more common elements contained in the $_ENV array:

$_SERVER['PATH']: environment variable PATH path.

$_SERVER['CLASSPATH']: System CLASSPATH path.

$_SERVER['LIB']: System LIB library path.

$_SERVER['INCLUDE']: System Include path. Note that it is different from PHP's include path.

$_SERVER['OS']: Operating system type.

$_SERVER['LANG']: system language, such as en_US or zh_CN.

$_SERVER['PWD']: Current working directory.

$_SERVER['TEMP']: System TEMP path.

$_SERVER['AP_PARENT_PID']: Current process ID number.

$_SERVER['NUMBER_OF_PROCESSORS']: Number of system CPUs.

Reasons why $_ENV is empty and solutions

If the printout $_ENV is empty, you can check the configuration of php.ini:

variables_order = "EGPCS"

The above configuration represents the source and order of external variables accepted by PHP. EGPCS is the abbreviation of Environment, Get, Post, Cookies and Server. If E is missing from the configuration of variables_order, PHP cannot accept environment variables, and $_ENV will be empty.

Original address: http://www.5idev.com/p-php_env.shtml

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