solve review comments

Author: zhzhan

sbin/spark-daemon.sh

@@ -168,7 +168,7 @@ case $option in
       TARGET_ID="$(cat "$pid")"
       if [[ $(ps -p "$TARGET_ID" -o comm=) =~ "java" ]]; then
         echo "stopping $command"
-        kill "$TARGET_ID" && rm -f $pid
+        kill "$TARGET_ID" && rm -f "$pid"
       else
         echo "no $command to stop"
       fi