The Disks application is single-instance. What this means is that if the application is not already running when the gnome-disks command is invoked, it will get launched and the command invocation will block until the application exits. Otherwise the existing application instance will be used and the gnome-disks command will exit immediately.
The following options are understood:
--block-device DEVICE --format-device [--xid WINDOW-ID]
Written by David Zeuthen <email@example.com> with a lot of help from many others.
Please send bug reports to either the distribution bug tracker or the upstream bug tracker at m[blue]https://bugzilla.gnome.org/enter_bug.cgi?product=gnome-disk-utilitym.