It used to be possible run inkscape from the command line as a convenient tool for convert to and from SVG files. Lots of questions here have answers that suggest running inkscape -z with various other arguments as a tool to do these conversions. Unfortunately this stopped working at some point in the last few years. The -z option is no longer documented and produces a warning that the option is ‘deprecated’ (in fact, it’s simply ignored), and then fails because X is not running: