-    disconnected=`grep -c DISCONNECTED /sys/devices/virtual/android_usb/android0/state`;
-    if [ -z "$disconnected" ] || [ "$disconnected" -ge 1 ];
-    then
-        stop; exit 0;
-    fi
+    test -e /sys/devices/virtual/android_usb/android0/state || { stop; exit 0; }
+    grep -q DISCONNECTED /sys/devices/virtual/android_usb/android0/state && { stop; exit 0; }
+    grep -q mtp /sys/devices/virtual/android_usb/android0/functions || { stop; exit 0; }