First, make a directory for mod_perl programs. This directory can be anywhere, except that it's a bad idea to put it in the Apache document tree starting with /var/wwwl for the same reasons that it is a bad idea to do so for CGI programs. Let's choose /var/www/mod_perl. Create the directory with the appropriate permissions:
# mkdir /var/www/mod_perl # chmod a+rx /var/www/mod_perl
Apache needs to be configured appropriately to use mod_perl effectively. We start by creating a Perl script that Apache runs each time it starts up (or more precisely, each time the Apache configuration file is reread). Name this program startup.pl, since it runs when Apache starts up, and put it in the Apache configuration directory /etc/httpd/conf:
#! /usr/bin/perl # tell Perl where to find our modules use lib ´/var/www/mod_perl´; # use some common modules use Apache::Registry(); use Apache::Constants(); use CGI ´:standard´; use DBI; # add other modules here... # the file needs to end with 1; 1;
The use lib statement tells Apache (really Perl that is built into Apache) where to find the mod_perl modules that we will writein this case, the newly minted /var/www/mod_perl directory.
The next four use statements preload four commonly used Perl modules. Preloading at server start-up speeds up loading the individual modules when they are used in the mod_perl programs [1]if this start-up script weren't used, the modules would have to be loaded the first time each mod_perl program executed, while the client waited for a response from the server.
[1] As you go along, add any other commonly used modules as needed.
The last line must be 1;strange, but important. This program, and all Perl modules, must end in 1; so that when they are used via the use pragma (use CGI;), the use must evaluate to 1 (true). To accomplish that, simply make the last line of the module 1;. This needs to be done for all the mod_perl modules.
Then configure Apache to execute the start-up script by adding these lines at the end of the Apache configuration file /etc/httpd/conf/httpd. conf:
PerlRequire conf/startup.pl PerlFreshRestart On
Restart Apache to test the start-up script:
# /etc/init.d/httpd graceful
and check the log file for error messages:
# tail -f /var/log/httpd/error_log
If you see no errors, all is well with the start-up script.