Recipe 8.21 Reading Environment Variables
8.21.1 Problem
You want
to get the value of an environment variable.
8.21.2 Solution
Read the value from the $_ENV superglobal array:
$name = $_ENV['USER'];
8.21.3 Discussion
Environment variables are named values associated with a process.
For instance, in Unix, you can check
the value of $_ENV['HOME'] to find the home
directory of a user:
print $_ENV['HOME']; // user's home directory
/home/adam
Early versions of PHP automatically created PHP variables for all
environment variables by default. As of 4.1.0,
php.ini-recommended disables this because of
speed considerations; however php.ini-dist
continues to enable environment variable loading for backward
compatibility.
The $_ENV
array is created only if the value of the
variables_order configuration directive
contains E. If $_ENV
isn't available, use getenv(
) to
retrieve an environment variable:
$path = getenv('PATH');
The getenv( ) function isn't
available if you're running PHP as an ISAPI module.
8.21.4 See Also
Recipe 8.22 on setting environment variables;
documentation on getenv( ) at
http://www.php.net/getenv; information on
environment variables in PHP at
http://www.php.net/reserved.variables.php#reserved.variables.environment.
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