Converting .odm to .odt or .pdf - command line

I saw this question: https://unix.stackexchange.com/questions/144054/converting-odm-to-odt , where someone shows to convert an .odm file into .odt or .pdf. Is there also a way to do this in a command line? I have an Open Document Master file, which has a link to two external files, but when I type: soffice --headless --convert-to pdf master.odm Then I only see a blank file. The same when I first try to convert into odt and then into pdf: soffice --headless --convert-to odt master.odm soffice --headless --convert-to pdf master.odt