There are several useful command line options:
skip root check
display the current version
open a new window
open a project
display this help screen
Many programs like browsers, email clients and file managers can be configured to open files in Bluefish. For example, bluefish '%s' will open a file in the current window, bluefish -n '%s' will open a file in a new window, and bluefish -p '%s' will open a project file.