Start long running process from Makefile in portable way?

[Oleksandr Gavenko]

I want start long running process from Makefile.

To do this I finally wrote:

.PHONY: run
run: targ1 targ2
    nohup  xterm -e command arg1 arg2  </dev/null  2<&- 1<&- &

Now after invoking "make run" make do it's job, run "xterm"
and exit. "xterm" stay alive.


What I really need from "nohup  ...   </dev/null  2<&- 1<&- &" magic?


Under Cygwin this work (without '1<&-', '2<&-', '&' make wait
to exit XWin):

    exec 1<&-; exec 2<&-; XWin -multiwindow &

But on Linux host this line work (without 'nohup' make wait
for xterm):

    nohup xterm &

I try read POSIX 2008 but it seems too complicate to me (very
very long text to get answer in near future).

Can some one explain what part essential for portable solution?

--
С уважением, Александр Гавенко.