diff --git a/test/async-unison/Makefile b/test/async-unison/Makefile
index 0687092d8020acb16aa63c2028f8a0e24264e1cf..3109e40dd943937a610f28d3605fa71aba804ad0 100644
--- a/test/async-unison/Makefile
+++ b/test/async-unison/Makefile
@@ -20,7 +20,7 @@ lurette: ring.cmxs ring_oracle.lus
 		-oracle "lv6 -2c-exec ring_oracle.lus -n oracle" 
 
 rdbg_test: ring.ml
-	echo "\nnr\nsd\nq\n" | rdbg  -o ring.rif -l 10000 -env "$(sasa) -vl 1 ring.dot -cd" 
+	printf "\nnr\nsd\nq\n" | rdbg  -o ring.rif -l 10000 -env "$(sasa) -vl 1 ring.dot -cd" 
 
 rdbg: ring.ml
 	rdbg -o ring.rif -l 10000 -env "sasa -vl 1 ring.dot -cd" 
diff --git a/test/dfs/Makefile b/test/dfs/Makefile
index 8d3e4b19813feb0dc3294873827b7405421a67b6..2ed9914d4c77bd8621c48111b7abdc366b0a0f6a 100644
--- a/test/dfs/Makefile
+++ b/test/dfs/Makefile
@@ -35,7 +35,7 @@ rdbg2: g.lut g.ml
       -sut-nd "lutin g.lut -n dummy"
 
 rdbg_test: g.lut g.ml
-	echo "\nnr\nsd\nq\n" | rdbg -o lurette.rif  \
+	printf "\nnr\nsd\nq\n" | rdbg -o lurette.rif  \
       -env "$(sasa) g.dot  -rif" \
       -sut-nd "lutin g.lut -n dummy"
 
diff --git a/test/dijkstra-ring/Makefile b/test/dijkstra-ring/Makefile
index c1f82931af99d21caf8488200b95f107257d4c02..f6d0d7aafc14e5a54fc9448cd6dae60c5fb20683 100644
--- a/test/dijkstra-ring/Makefile
+++ b/test/dijkstra-ring/Makefile
@@ -33,7 +33,7 @@ rdbg2: ring.ml ring.lut
       -sut-nd "lutin ring.lut -n distributed"\
 
 rdbg_test: ring.ml
-	echo "\nnr\nsd\nq\n" | rdbg  -o ring.rif -l 10000 -sut "$(sasa) -vl 1 ring.dot -dd" 
+	printf "\nnr\nsd\nq\n" | rdbg  -o ring.rif -l 10000 -sut "$(sasa) -vl 1 ring.dot -dd" 
 
 lurette1: ring.lut ring_oracle.lus
 	lurette \
diff --git a/test/unison/Makefile b/test/unison/Makefile
index 9d10721372b1d170f619fb7a8b9379ed2f476f33..6473f001a9e063f86121e53326da29229d9746f4 100644
--- a/test/unison/Makefile
+++ b/test/unison/Makefile
@@ -58,7 +58,7 @@ rdbg2: ring.ml
 	rdbg -o unison.rif -sut "sasa ring.dot -custd -rif" 
 
 rdbg_test: ring.ml
-	echo "\nn\ns\nsi 4\nn\nni 3\nq\n" | rdbg -o unison.rif  \
+	printf "\nn\ns\nsi 4\nn\nni 3\nq\n" | rdbg -o unison.rif  \
       -sut "$(sasa) ring.dot -sd -rif" \
 
 -include ../Makefile.inc