Recipe 8.22 Setting Environment Variables
8.22.1 Problem
You want
to set an environment variable in a script or in your server
configuration. Setting environment variables in your server
configuration on a host-by-host basis allows you to configure virtual
hosts differently.
8.22.2 Solution
To set an environment variable in a script, use putenv(
):
putenv('ORACLE_SID=ORACLE'); // configure oci extension
To set an environment variable in your Apache httpd.conf
file, use SetEnv:
SetEnv DATABASE_PASSWORD password
8.22.3 Discussion
An advantage of setting variables in httpd.conf
is that you can set more restrictive read permissions on it than on
your PHP scripts. Since PHP files need to be readable by the
web-server process, this generally allows other users on the system
to view them. By storing passwords in
httpd.conf, you can avoid placing a password in
a publicly available file. Also, if you have multiple hostnames that
map to the same document root, you can configure your scripts to
behave differently based on the hostnames.
For example, you could have members.example.com
and guests.example.com. The members version
requires authentication and allows users additional access. The
guests version provides a restricted set of options, but without
authentication:
$version = $_ENV['SITE_VERSION'];
// redirect to http://guest.example.com, if user fails to sign in correctly
if ('members' == $version) {
if (!authenticate_user($_REQUEST['username'], $_REQUEST['password'])) {
header('Location: http://guest.example.com/');
exit;
}
}
include_once "${version}_header"; // load custom header
8.22.4 See Also
Recipe 8.21 on getting the values of
environment variables; documentation on putenv( )
at http://www.php.net/putenv; information on
setting environment variables in Apache at
http://httpd.apache.org/docs/mod/mod_env.html.
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