Table 4-1 depicts where the various mod_perl configuration directives can be used.

Table 4-1. The Scope of mod_perl configuration directives

Directive

Global

<VirtualHost>

<Directory>

PerlTaintCheck

V
    

PerlWarn

V
    

PerlFreshRestart

V
    

PerlPassEnv

V
V
  

PerlRequire

V
V
V

PerlModule

V
V
V

PerlAddVar

V
V
V

PerlSetEnv

V
V
V

PerlSetVar

V
V
V

PerlSetupEnv

V
V
V

PerlSendHeader

V
V
V

<Perl> Sections

V
V
V

The first column represents directives that can appear in the global configuration; that is, outside all sections. Note that PerlTaintCheck, PerlWarn, and PerlFreshRestart can be placed inside <VirtualHost>sections. However, because there's only one Perl interpreter for all virtual hosts and the main server, setting any of these values in one virtual host affects all other servers. Therefore, it's probably a good idea to think of these variables as being allowed only in the global configuration.

The second column represents directives that can appear inside the <VirtualHost>sections.

The third column represents directives that can appear in the <Directory>, <Location>, and <Files>sections and all their regex variants. These mod_perl directives can also appear in .htaccess files.

For example, PerlWarn cannot be used in <Directory> and <VirtualHost>sections. However, PerlSetEnv can be used anywhere, which allows you to provide different behavior in different sections:

PerlSetEnv ADMIN_EMAIL webmaster@example.com
<Location /bar/manage/>
    PerlSetEnv ADMIN_EMAIL bar@example.com
</Location>

In this example, a handler invoked from /bar/manage/ will see the ADMIN_EMAIL environment variable as bar@example.com, while other handlers configured elsewhere will see ADMIN_EMAIL as the default value, webmaster@example.com.