diff --git a/make/defs.mk b/make/defs.mk
index 03e5de32..e9c5aee7 100644
--- a/make/defs.mk
+++ b/make/defs.mk
@@ -2,12 +2,14 @@
 # contact@jannet.de
 # $Id$
 
-# SHELL = $(MOD_SCRIPT_DIR)/timed-make-shell.sh
-
 ifndef YTOOLS_DEF_MK_INCLUDED
 YTOOLS_DEF_MK_INCLUDED = true
 include $(MODDIR)/make/platform.mk
 
+ifeq ($(MAKE_BENCHMARK),true)
+SHELL = $(MOD_SCRIPT_DIR)/timed-make-shell.sh
+endif
+
 proj_query  = $(shell python $(MOD_SCRIPT_DIR)/projects.py -p $(PROJECTS_DIR) -t $(TOPDIR) $(PROJECTS_PY_EXTRA_ARGS) $(1))
 proj_dir    = $(call proj_query,proj-dir $(1))
 htdocs_dir  = $(call proj_query,htdocs-dir $(1))
@@ -29,7 +31,7 @@ endif
 # ----- executables
 SED                    = sed
 CAT                    = /bin/cat
-SHELL                  = /bin/bash
+SHELL                 ?= /bin/bash
 
 # ----- standard variables
 ifeq ($(PROJECT),)
@@ -1048,5 +1050,15 @@ BUILD_LDFLAGS             += $(LOCAL_LDFLAGS) $(PROJECTLIB_LDFLAGS) $(PROJECT_LD
 #RPM_REQUIRES               = $(shell echo "$(RPM_REQUIRES_RUN) $(RPM_REQUIRES_DEVEL)" | $(add_flavour_prefix))
 RPM_REQUIRES              += $(RPM_REQUIRES_RUN) $(RPM_REQUIRES_DEVEL)
 
+all:
+
+nothing:
+
+echo-vars:
+	make -p nothing | grep -B1 "^[A-Z_]* *[?:]*="
+
+echo-makefiles:
+	strace -f make nothing 2>&1 | sed '/open(.*\(Makefile\|\.mk\)/ !d; s/.*open("//; s/", O_.*//'
+
 endif