mod_setenvif allows manipulation of environment variables. Using small snippets of text-matching code known as regular expressions, you can conditionally change the content of environment variables. The order in which
SetEnvIf directives appear in the configuration files is important. Each
SetEnvIf directive can reset an earlier
SetEnvIf directive when used on the same environment variable. Be sure to keep that in mind when using the directives from this module.