pre-network-manager-config.service

[Unit]
Description=Prepare network manager config content
Before=NetworkManager.service
DefaultDependencies=no

[Service]
User=root
Type=oneshot
TimeoutSec=60
ExecStart=/bin/bash /usr/local/bin/pre-network-manager-config.sh
PrivateTmp=true
RemainAfterExit=no

[Install]
WantedBy=multi-user.target