Improve rss_monitor startup (#346) 04/27/2022

And shut down if we hae no wifi to monitor

files/usr/local/bin/mgr/rssi_monitor.lua

@@ -35,13 +35,16 @@
 --]]
 
 function rssi_monitor()
+    if string.match(get_ifname("wifi"), "^eth.") then
+        exit_app()
+    else
+        wait_for_ticks(math.max(1, 120 - nixio.sysinfo().uptime))
         while true
         do
-        if not string.match(get_ifname("wifi"), "^eth.") and nixio.sysinfo().uptime > 119 then
             run_monitor()
-        end
             wait_for_ticks(60) -- 1 minute
         end
+    end
 end
 
 local datfile = "/tmp/rssi.dat"