calibre-debug(1) on Linux
The text acea8f9892f5, as Debian 10 (Buster) shipped it.
calibre-debug Various command line interfaces useful for debugging calibre. With no options, this command starts an embedded Python interpreter. You can also run the main calibre GUI, the calibre viewer and the calibre editor in debug mode. It also contains interfaces to various bits of calibre that do not have dedicated command line tools, such as font subsetting, the e-book diff tool and so on. You can also use calibre-debug to run standalone scripts. To do that use it like this: Everything after the -- is passed to the script. Whenever you pass arguments to calibre-debug that have spaces in them, enclose the arguments in quotation marks. For example: "/some path/with spaces"