Sorry--I didn't realize you were only interested in a command line scan. Here is some info about command line scanning at
https://forum.fortinet.com/tm.aspx?m=96658 on the web--it doesn't look like it is possible.
Since the purchase of Clam AV by Cisco and the loss of the original Clam AV development team before that, ClamWin does not have any contact(s) with the Clam AV team at Cisco. Clam AV is not a commercial product at Cisco, and it does not have much priority there. As far as I know, there is no one working on Clam AV on a full-time basis. In the past they have worked on Clam only when they are not performing their primary duties.
Compacting the database used to be a tricky thing. I doubt that even now, anyone at Cisco attempting it will know how to do it without some detailed study. The first attempt after the original Clam AV team left was a fiasco.
I think that Windows Defender is all you need for email scanning. It is much better than Clam AV/ClamWin. It is under continuous development by a full-time, professional team that uses the latest technology. There are well over 300,000 new forms of malware each day, but Clam AV only prepares about 1,000 daily malware signatures. Clam AV has practically no heuristics, and there is no use of machine learning/AI.
Regards,