$_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
$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)
Introduced $_ENV that deprecated
Example #1 $_ENV example
echo 'My username is ' .$_ENV["USER"] . '!';
Assuming "bjori" executes this script
The above example will output
something similar to:
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.