Fix a sending signal error when starting Doris BE (#367)

Redirect output message of kill to /dev/null.

Co-Authored-By: chalsliu <45041955+chalsliu@users.noreply.github.com>

ISSUE #365

bin/start_be.sh

@@ -55,14 +55,14 @@ rm -f ${UDF_RUNTIME_DIR}/*
 pidfile=$PID_DIR/be.pid
 
 if [ -f $pidfile ]; then
-    if kill -0 $(cat $pidfile); then
+    if kill -0 $(cat $pidfile) > /dev/null 2>&1; then
         echo "Backend running as process `cat $pidfile`. Stop it first."
         exit 1
     else
         rm $pidfile
     fi
 fi
- 
+
 chmod 755 ${DORIS_HOME}/lib/palo_be
 echo "start time: "$(date) >> $LOG_DIR/be.out