autogain suspend: don't output autogain script messages (#241)

rootfs/etc/s6-overlay/scripts/autogain

@@ -27,26 +27,33 @@ if [[ "${READSB_DEVICE_TYPE,,}" != "rtlsdr" ]]; then
     stop_service
 fi
 
-mkdir -p /var/globe_history/autogain
+autogain_dir="/var/globe_history/autogain"
+
+# if autogain is suspended, sleep for an hour, after that this script will check again if still suspended
+[[ -f "${autogain_dir}/suspend" ]] && exec sleep 3600
+
+mkdir -p "${autogain_dir}"
 
 # wait a bit so stats.json is present
 sleep 5
 
 # Do special things if it's the first time AUTOGAIN is running
-if [[ ! -f /var/globe_history/autogain/autogain_initialized ]]; then
+if [[ ! -f $autogain_dir/autogain_initialized ]]; then
+    [[ -f "${autogain_dir}/suspend" ]] && exec sleep 3600
     s6wrap --quiet --prepend=autogain --timestamps --args echo "Autogain initialization started. We'll collect data every $READSB_AUTOGAIN_INITIAL_INTERVAL secs for $(( READSB_AUTOGAIN_INITIAL_TIMEPERIOD / 60 )) minutes to do an initial gain assessment."
     # run autogain every $READSB_AUTOGAIN_INITIAL_INTERVAL secs (default 5 mins) for $READSB_AUTOGAIN_INITIAL_TIMEPERIOD secs (default 2 hours)
     for (( i=0; i<$(( READSB_AUTOGAIN_INITIAL_TIMEPERIOD / READSB_AUTOGAIN_INITIAL_INTERVAL )); i++ ))
     do
         sleep "$READSB_AUTOGAIN_INITIAL_INTERVAL" & wait $!  # sleep first to give readsb the opportunity to collect some initial data
         s6wrap --quiet --prepend=autogain --timestamps --args /usr/local/bin/autogain1090
     done
-    touch /var/globe_history/autogain/autogain_initialized
+    touch "${autogain_dir}"/autogain_initialized
 fi
 
 s6wrap --quiet --prepend=autogain --timestamps --args echo "Autogain long-term maintenance started. We'll collect data and assess every $(( READSB_AUTOGAIN_SUBSEQUENT_INTERVAL / 60 )) minutes if gain needs to be adjusted."
 while true
 do
+    [[ -f "${autogain_dir}/suspend" ]] && exec sleep 3600
     sleep "$READSB_AUTOGAIN_SUBSEQUENT_INTERVAL" & wait $!
     s6wrap --quiet --prepend=autogain --timestamps --args /usr/local/bin/autogain1090
 done