From the mid-1990s we have developed and enhanced causal discovery software for learning causal Bayesian networks from sample data using an MML measure. We have now made linear CaMML available after some years of absence, when we exclusively focused on developing discrete CaMML. Discrete CaMML has been available for some years via Rodney O'Donnell's github web page, but we link into it now through our "Software" page. The user interfaces for these programs are not exactly user friendly; however, a GUI has been developed for discrete CaMML and should become available reasonably soon.