`hostname -I` is GNU-only and errors on BSD/macOS, so when the public-IP
curl couldn't reach api.ipify.org the script printed nothing and the
tmux status bar showed an empty IP. Try `ipconfig getifaddr` for common
interfaces first, fall back to `hostname -I` on Linux, then `ifconfig`
as a last resort. Also guard against empty-but-zero-exit curl output.
dissimulo
467b967ced