Network Manager Dispatcher returns error code 1 on tested scripts

Question

I'm trying to write a simple script to test the network manager dispatcher but while it's working when I manually launch the script, the nm dispatcher print "nm-dispatcher.action: Script '/etc/NetworkManager/dispatcher.d/start_dropbox.sh' exited with error status 1" into the logs.
#!/bin/sh
IF=$1
STATUS=$2
/bin/su USERNAME -c "/usr/bin/notify-send lol woot"
exit $?
I tried using absolute paths, just the commands, running with sudo(although the scripts should be run as root) and without su. I tested the script as root and as a simple user using a terminal and it works just fine every time.
echo seems to work fine as I don't get any errors in the logs, but that way I can't see what's inside $1 and $2 when the dispatcher calls the script and I can't think of any way to debug the script which doesn't involve notify-send.
I'm sure I'm missing something very simple here, but I can't see it myself and searching google and the arch forums hasn't helped me any.

Answer 1

I solved the problem. Here is a little explanation.
After NetworkManager establishes network connection, NetworkManager-dispatcher service is started( for ~10 seconds). This service execute /usr/lib/networkmanager/nm-dispatcher.action, which execute scripts in /etc/NetworkManager/dispatcher.d. After exiting nm-dispatcher.action mount.davfs process appears in NetworkManager-dispatcher`s CGroup. By default all processes in CGroup must be killed when service stops. To change this behavior I have added KillMode=process to [Service] section of NetworkManager-dispatcher.service file.
sudo nano /usr/lib/systemd/system/NetworkManager-dispatcher.service
Here is it`s code now.
[Unit]
Description=Network Manager Script Dispatcher Service
[Service]
Type=dbus
BusName=org.freedesktop.nm_dispatcher
ExecStart=/usr/lib/networkmanager/nm-dispatcher.action
KillMode=process
[Install]
WantedBy=multi-user.target
Alias=dbus-org.freedesktop.nm-dispatcher.service