To get a brief listing of the command-line parameters known to your version of Inkscape, run it with --help. A more detailed reference is available from Inkscape’s UI in Help ▸ Command Line Options (this opens a web browser and fetches the page from the Internet) or by typing man inkscape on the command line (Linux only).
A very useful parameter (especially if you are going to report a bug or request a feature from Inkscape developers) is --version which prints the exact version and even the SVN revision number of your copy of Inkscape.