root@powerpi:~# cat
# put in /lib/systemd/system/yourservice.service
# and then
# dont forget to:
#
# sudo systemctl daemon-reload        # to reload changes to services and in particular yourservice.service
# sudo systemctl enable yourservice   # to enable yourservice.service at upstart
# sudo systemctl start yourservice    # to start yourservice.service
#
# systemd service below:

[Unit]
Description=Your service to start a script after network.target
Documentation=http://somesoftware.com/about
After=network.target

[Service]
Type=simple
User=root
WorkingDirectory=/path/to/your
ExecStart=/bin/bash /path/to/your/script.sh
Restart=no

[Install]
WantedBy=multi-user.target