@Ralph A Can I safely assume the following:
If a CGI Web app is already running when a user hits it, its CGI script will not execute. That is, the CGI script is run only when a user hits the Web app during a time when the app is not running (e.g., after AutoQuit stopped the app).
The cgi script is always used, regardless of whether the app is running or not. If it’s not, it attempts to launch the app. It then acts as a conduit.
@Ralph A Put another way, can I assume that this error.log message only occurs if the CGI app crashed after the CGI script attempted to start it:
Can't use an undefined value as a symbol reference at [...].cgi line 118.
That is, I wouldn't see such an error coming from a CGI app that was running when the user hit it.
I usually see this when someone attempts to run the cgi script from the command line and not a web server.