ff opts

 /usr/bin/firefox -h
Usage: /usr/lib/firefox/firefox [ options ... ] [URL]
       where options include:

X11 options
  --display=DISPLAY  X display to use
  --sync             Make X calls synchronous
  --g-fatal-warnings Make all warnings fatal

Firefox options
  -h or --help       Print this message.
  -v or --version    Print Firefox version.
  --full-version     Print Firefox version, build and platform build ids.
  -P <profile>       Start with <profile>.
  --profile <path>   Start with profile at <path>.
  --migration        Start with migration wizard.
  --ProfileManager   Start with ProfileManager.
  --no-remote        Do not accept or send remote commands; implies
                     --new-instance.
  --new-instance     Open new instance, not a new window in running instance.
  --safe-mode        Disables extensions and themes for this session.
  --allow-downgrade  Allows downgrading a profile.
  --MOZ_LOG=<modules> Treated as MOZ_LOG=<modules> environment variable,
                     overrides it.
  --MOZ_LOG_FILE=<file> Treated as MOZ_LOG_FILE=<file> environment variable,
                     overrides it. If MOZ_LOG_FILE is not specified as an
                     argument or as an environment variable, logging will be
                     written to stdout.
  --headless         Run without a GUI.
  --jsdebugger [<path>] Open the Browser Toolbox. Defaults to the local build
                     but can be overridden by a firefox path.
  --wait-for-jsdebugger Spin event loop until JS debugger connects.
                     Enables debugging (some) application startup code paths.
                     Only has an effect when `--jsdebugger` is also supplied.
  --start-debugger-server [ws:][ <port> | <path> ] Start the devtools server on
                     a TCP port or Unix domain socket path. Defaults to TCP port
                     6000. Use WebSocket protocol if ws: prefix is specified.
  --browser          Open a browser window.
  --new-window <url> Open <url> in a new window.
  --new-tab <url>    Open <url> in a new tab.
  --private-window <url> Open <url> in a new private window.
  --preferences      Open Preferences dialog.
  --screenshot [<path>] Save screenshot to <path> or in working directory.
  --window-size width[,height] Width and optionally height of screenshot.
  --search <term>    Search <term> with your default search engine.
  --setDefaultBrowser Set this app as the default browser.
  --first-startup    Run post-install actions before opening a new window.
  --kiosk            Start the browser in kiosk mode.
  --disable-pinch    Disable touch-screen and touch-pad pinch gestures.
  --jsconsole        Open the Browser Console.
  --jsdebugger [<path>] Open the Browser Toolbox. Defaults to the local build
                     but can be overridden by a firefox path.
  --wait-for-jsdebugger Spin event loop until JS debugger connects.
                     Enables debugging (some) application startup code paths.
                     Only has an effect when `--jsdebugger` is also supplied.
  --devtools         Open DevTools on initial load.
  --start-debugger-server [ws:][ <port> | <path> ] Start the devtools server on
                     a TCP port or Unix domain socket path. Defaults to TCP port
                     6000. Use WebSocket protocol if ws: prefix is specified.
  --marionette       Enable remote control server.
  --remote-debugging-port [<port>] Start the Firefox Remote Agent,
                     which is a low-level remote debugging interface used for WebDriver
                     BiDi and CDP. Defaults to port 9222.
  --remote-allow-hosts <hosts> Values of the Host header to allow for incoming requests.
                     Please read security guidelines at https://firefox-source-docs.mozilla.org/remote/Security.html
  --remote-allow-origins <origins> Values of the Origin header to allow for incoming requests.
                     Please read security guidelines at https://firefox-source-docs.mozilla.org/remote/Security.html