docker-adsb-ultrafeeder/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart

#!/command/with-contenv bash
# shellcheck shell=bash disable=SC2015,SC2016,SC1091,SC2001,SC2154

#---------------------------------------------------------------------------------------------
# Copyright (C) 2023-2024, Ramon F. Kolb (kx1t) and contributors
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with this program.
# If not, see <https://www.gnu.org/licenses/>.
#---------------------------------------------------------------------------------------------

source /scripts/common

# Check every 60 secs if GPSD has been enabled
if [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; then
    sleep 60 & wait $!
fi

# Then wait until all mlat-client instances have started
while [[ ! -f /run/.all_mlatclient_instances_have_started ]]; do
    sleep 5 & wait $!
done

rm -f /run/.all_mlatclient_instances_have_started

# Now wait a bit to allow GPS to establish itself
sleep "${GPSD_INITIAL_WAIT:-60}"

# Get initial lat/lon/alt
lat="${LAT:-${READSB_LAT:-$(jq -r .lat /run/readsb/gpsd.json)}}"
lon="${LONG:-${READSB_LON:-$(jq -r .lon /run/readsb/gpsd.json)}}"

while :; do
    new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
    new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
    distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
    if (( ${distance%%.*} > GPSD_MIN_DISTANCE )); then
        "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
        # flag to the mlat-client script that it should try to use GPS coords instead of the predefined LAT/LON
        touch /run/.gpsd_is_active
        # kill the mlat-client instances so they get restarted with the new GPS coords
        pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
    fi
    sleep "${GPSD_CHECK_INTERVAL:30}" & wait $!
done