Environment variables used with CGI scripts
Environment variables are used in CGI scripts to represent information that is updated by the Web server when the scripts run. Using environment variables, scripts can get and use up-to-date information without having to store that information themselves.
In addition to the standard environment variables, the following three environment variables are available to all scripts on your site:
SITE_ROOT. The root path of your site
SITE_CGIROOT. The top level CGI path of your site
SITE_HTMLROOT. The top level HTML CGI path of your site
You can use these variables in your CGI scripts to avoid hard-coding directory path names. This ensures that path names are always correct, even if those path names change.