If your $_ENV array is mysteriously empty, but you still see the variables when calling getenv() or in your phpinfo(), check your http://us.php.net/manual/en/ini.core.php#ini.variables-order ini setting to ensure it includes "E" in the string.
(PHP 4 >= 4.1.0, PHP 5, PHP 7)
$_ENV -- $HTTP_ENV_VARS [deprecated] — Environment variables
An associative array of variables passed to the current script via the environment method.
These variables are imported into PHP's global namespace from the environment under which the PHP parser is running. Many are provided by the shell under which PHP is running and different systems are likely running different kinds of shells, a definitive list is impossible. Please see your shell's documentation for a list of defined environment variables.
Other environment variables include the CGI variables, placed there regardless of whether PHP is running as a server module or CGI processor.
$HTTP_ENV_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_ENV_VARS and $_ENV are different variables and that PHP handles them as such)
| Version | Description |
|---|---|
| 4.1.0 | Introduced $_ENV that deprecated $HTTP_ENV_VARS. |
Example #1 $_ENV example
<?php
echo 'My username is ' .$_ENV["USER"] . '!';
?>
Assuming "bjori" executes this script
The above example will output something similar to:
My username is bjori!
Note:
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
If your $_ENV array is mysteriously empty, but you still see the variables when calling getenv() or in your phpinfo(), check your http://us.php.net/manual/en/ini.core.php#ini.variables-order ini setting to ensure it includes "E" in the string.
Please note that writing to $_ENV does not actually set an environment variable, i.e. the variable will not propagate to any child processes you launch (except forked script processes, in which case it's just a variable in the script's memory). To set real environment variables, you must use putenv().
Basically, setting a variable in $_ENV does not have any meaning besides setting or overriding a script-wide global variable. Thus, one should never modify $_ENV except for testing purposes (and then be careful to use putenv() too, if appropriate).
PHP will not trigger any kind of error or notice when writing to $_ENV.
If $_ENV is empty because variables_order does not include it, it will be filled with values fetched by getenv().
For example, when calling getenv("REMOTE_ADDR"), $_ENV['REMOTE_ADDR'] will be defined as well (if such an environment variable exists).
Comments for this page seem to indicate getenv() returns environment variables in all cases.
For getenv() to work, php.ini variables_order must contain 'E'.
If you wish to define an environment variable in your Apache vhost file, use the directive SetEnv.
SetEnv varname "variable value"
It is important to note that this new variable will appear in $_SERVER, not $_ENV.
When running a PHP program under the command line, the $_SERVER["SERVER_NAME"] variable does not contain the hostname. However, the following works for me under Unix/Linux and Windows:
<?php
if (isset($_ENV["HOSTNAME"]))
$MachineName = $_ENV["HOSTNAME"];
else if (isset($_ENV["COMPUTERNAME"]))
$MachineName = $_ENV["COMPUTERNAME"];
else $MachineName = "";
?>