option to disable updates on mobile (data) networks

[lectrode]

The update script should optionally not download or install updates when the only connection is mobile/data (most cellular services do not have actual unlimited data). This would still be allowed by default for security reasons, as well as to avoid impacting existing devices.

Preliminary search shows that networks provided by cellular carriers will have a qmi folder under the system network location.
example:

$ [[ -d "/sys/class/net/wwan0/qmi" ]] && echo this is a mobile data network

This is not the case on wired or wifi connections.

I should be able to use this in conjunction with the following to narrow down whether or not the only active connection is mobile.
ip --brief addr

better method:
cat /sys/class/net/wwan0/operstate

I'll also need to exclude loopback and anbox connections. All relevant network connections should have a device subfolder.

[[ -d "/sys/class/net/wlan0/device" ]] && echo not a loopback or bridge connection