executing script in fork

[cerr]

Hi There,

I want to trigger another script and having it running forked to my
mother process.
I googled around and came up with following:

commandlist=['./GPSsim.pl',proto,'files/gps.txt']
subprocess.Popen(commandlist)
print "GPS simulator started"

This however doesn't seem disconnect stdout but it still throws me
back to the shell.
How can I launch it with disconnected stdout and still continue
running further code in my mother script?

Thanks,
Ron