Question about file desriptors.

[Stef Bon]

Hello,

when I look at the processlist with ps on my machine, I see something like:

dbus-daemon --fork --print-pid 6 --print-address 8 --session

It's launched by the dbus-launch program, right?
If I've understood this dbus-launch program on his turn is started by 
the system dbus-daemon,
when it recieves an call from an user without dbus-daemon running for 
his session.

Is it really neccesary that the dbus-daemon for a session is started by 
dbus-launch? I've read that
the filedescriptors  are used by programs that launch the message bus. 
Is this mandatory??

Some time ago I've used a construction to start the dbus-daemon for a 
session just by a script,
writing the output to a file (which then contains the address and the 
pid) which is sourced by the bash
shell when it starts. Is there something against this construction?

Thanks in advance,

Stef Bon