diff --git a/bin/progress_bar.sh b/bin/progress_bar.sh
index 68243444..ebd8f902 100755
--- a/bin/progress_bar.sh
+++ b/bin/progress_bar.sh
@@ -38,5 +38,6 @@ else
   rm -f "$stderr_log"
   unset stderr_log design
   wait $_PID
+  unset $_PID
   set -m
 fi
diff --git a/missions/stdin_stdout_stderr/05_stdout_stderr_redirection_merlin/init.sh b/missions/stdin_stdout_stderr/05_stdout_stderr_redirection_merlin/init.sh
index cfa79bd7..769cdd7e 100644
--- a/missions/stdin_stdout_stderr/05_stdout_stderr_redirection_merlin/init.sh
+++ b/missions/stdin_stdout_stderr/05_stdout_stderr_redirection_merlin/init.sh
@@ -1,30 +1,35 @@
 #!/bin/bash
 
-mkdir -p "$(eval_gettext '$GSH_HOME/Castle/Observatory')"
+_mission_init() {
+  mkdir -p "$(eval_gettext '$GSH_HOME/Castle/Observatory')"
 
-random_string 200 > "$GSH_VAR/secret_key"
+  random_string 200 > "$GSH_VAR/secret_key"
 
-if command -v cc >/dev/null
-then
-  CC=cc
-elif command -v c99 >/dev/null
-then
-  CC=c99
-elif command -v gcc >/dev/null
-then
-  CC=gcc
-elif command -v clang >/dev/null
-then
-  CC=clang
-fi
+  local CC
+  if command -v cc >/dev/null
+  then
+    CC=cc
+  elif command -v c99 >/dev/null
+  then
+    CC=c99
+  elif command -v gcc >/dev/null
+  then
+    CC=gcc
+  elif command -v clang >/dev/null
+  then
+    CC=clang
+  fi
 
-# certains se débrouillent pour écraser merlin ! Il faut mieux le regénérer,
-# même si le fichier existe !
-if [ -n "$CC" ]
-then
-  $CC "$MISSION_DIR/merlin.c" -o "$GSH_VAR/merlin"
-  copy_bin  "$GSH_VAR/merlin" "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
-else
-  copy_bin  "$MISSION_DIR"/merlin.sh "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
-  chmod 755 "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
-fi
+  # some student erase merlin, for example with $ ./merlin > merlin or similar.
+  # It is better to re-generate it each time!
+  if [ -n "$CC" ]
+  then
+    $CC "$MISSION_DIR/merlin.c" -o "$GSH_VAR/merlin"
+    copy_bin  "$GSH_VAR/merlin" "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
+  else
+    copy_bin  "$MISSION_DIR"/merlin.sh "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
+    chmod 755 "$(eval_gettext '$GSH_HOME/Castle/Observatory')/merlin"
+  fi
+}
+
+_mission_init