fix: for child shell

scripts/router_local_update.sh

@@ -185,7 +185,7 @@ EOF
 EOF
 }
 
-run_cfst() {
+run_cfst() (
   cd "$CFST_WORK_DIR"
   set -- "$CFST_BIN" -f "$CFST_IP_FILE" -o "$CFST_RESULT_FILE" -p "$CFST_DISPLAY_COUNT" -tp "$CFST_PORT"
 
@@ -236,7 +236,7 @@ run_cfst() {
   fi
 
   "$@"
-}
+)
 
 LAST_GOOD_IP=$(json_get_string "$STATE_LAST_GOOD_KEY" "$STATE_PATH")