-P[pidfile], --pidfile[=pidfile]
    Causes a file (by default, .pid) to be created indicating the PID of the running process. If pidfile is not specified, or if it does not begin with /, then it is created in @RUNDIR@.

-f, --force
    By default, when -P or --pidfile is specified and the specified pidfile already exists and is locked by a running process, refuses to start. Specify -f or --force to cause it to instead overwrite the pidfile. When -P or --pidfile is not specified, this option has no effect.

-D, --detach
    Causes to detach itself from the foreground session and run as a background process.