Knock: Convert ACSM files to PDF/EPUBs with one command on Linux

Calibre has supported this for some time now. Calibre is also available on Linux.

What is an ASCM file? In forty plus years I've not encountered this extension.

Thanks! I needed this. My library has either ACSM or send to Kindle. So I cannot read it on my old Sony eBook reader. Until this.