"1. httpd -k
start -c "DocumentRoot /var/www/html_debug/": Start up Apache using
an alternative DocumentRoot. This is useful if you're trying out
alternative versions of your web site, as it avoids editing the
DocumentRoot option. You can also use -c to set any other
directive. Note that -c processes the directive after reading the
config files (so it will overwrite config file settings), whereas
-C will process the directive before the config files."