How to run long time process on Udev event?

Question

I want to run a ppp connection when my USB modem is connected, so I use this udev rule:

ACTION=="add", SUBSYSTEM=="tty", ATTRS{idVendor}=="16d8",\
    RUN+="/usr/local/bin/newPPP.sh $env{DEVNAME}"

(My modem appears in /dev as ttyACM0)

newPPP.sh:

#!/bin/bash
/usr/bin/pon prov $1 >/dev/null 2>&1 &

Problem:

The udev event fires, and newPPP.sh is running, but newPPP.sh process is killed after ~4-5s. ppp does not have time to connect (its timeout is 10s for dial up).

How can I run a long time process, that will not be killed?

I tried using nohup, but it didn't work either.

System: Arch Linux

Update

I found a solution here, thanks to maxschlepzig.

I use at now to run my job detached from udev process.

But the one question remains unanswered: Why do nohup and & not work?

Answer 1

Probably because its parent process is terminated and the termination signal propagates to its children, which don't block it (and in case of SIGKILL they even can't).