diff --git a/C/exec.c b/C/exec.c
index 0500d6857..7f3e22419 100755
--- a/C/exec.c
+++ b/C/exec.c
@@ -2258,8 +2258,7 @@ void Yap_InitExecFs(void) {
   Yap_InitCPred("$creep_step", 2, creep_step, NoTracePredFlag);
   Yap_InitCPred("$execute_clause", 4, execute_clause, NoTracePredFlag);
   Yap_InitCPred("$current_choice_point", 1, current_choice_point, 0);
-  Yap_InitCPred("$                                    ", 1,
-		current_choice_point, 0);
+  Yap_InitCPred("$current_choicepoint", 1, current_choice_point, 0);
   CurrentModule = HACKS_MODULE;
   Yap_InitCPred("current_choice_point", 1, current_choice_point, 0);
   Yap_InitCPred("current_choicepoint", 1, current_choice_point, 0);
@@ -2268,8 +2267,7 @@ void Yap_InitExecFs(void) {
   CurrentModule = cm;
   Yap_InitCPred("$restore_regs", 1, restore_regs,
 		NoTracePredFlag | SafePredFlag);
-  Yap_InitCPred("$restore_regs", 2, restore_regs2,
-		NoTracePredFlag | SafePredFlag);
+  Yap_InitCPred("$restore_regs", 2, restore_regs2,NoTracePredFlag  | SafePredFlag);
   Yap_InitCPred("$clean_ifcp", 1, clean_ifcp, SafePredFlag);
   Yap_InitCPred("qpack_clean_up_to_disjunction", 0, cut_up_to_next_disjunction,
 		SafePredFlag);
@@ -2279,6 +2277,6 @@ void Yap_InitExecFs(void) {
   Yap_InitCPred("$do_term_expansion", 2, do_term_expansion, 0);
   Yap_InitCPred("$setup_call_catcher_cleanup", 1, setup_call_catcher_cleanup,
 		0);
-  Yap_InitCPred("$cleanup_on_exit", 2, cleanup_on_exit, 0);
+  Yap_InitCPred("$cleanup_on_exit", 2, cleanup_on_exit, NoTracePredFlag);
   Yap_InitCPred("$tag_cleanup", 2, tag_cleanup, 0);
 }
diff --git a/docs/checkpl.yap b/docs/checkpl.yap
index cca01fde2..ba585e49d 100644
--- a/docs/checkpl.yap
+++ b/docs/checkpl.yap
@@ -1,12 +1,13 @@
 
 :- use_module(library(lists)).
 :- use_module(library(lineutils)).
+:- use_module(library(system)).
 
 :- initialization(main).
 
 main :-
-  %system('find . \( -name '*.pl' -o -name '*.yap'  -o -name '*.c' -o -name '*.h' -o -name '*.cpp' -o -name '*.hh' \) -type f -print | xargs grep  '@defgroup\|@ingroup\|@addtogroup\|@{|@}').
- file_filter_with_start_end( docs, tmp, add2graph, initgraph,  checkgraph).
+  popen('find . \\( -name \"*.pl\" -o -name \"*.yap\"  -o -name \"*.c\" -o -name \"*.h\" -o -name \"*.cpp\" -o -name \"*.hh\" \\) -type f -print | xargs grep  \"@defgroup\\|@ingroup\\|@addtogroup\\|@\\{\\|@\\}\"', read, S),
+ file_filter_with_start_end( S, user_output, add2graph, initgraph,  checkgraph).
 
 initgraph(_,_).
 
diff --git a/library/lineutils.yap b/library/lineutils.yap
index 67077e242..f32722e51 100644
--- a/library/lineutils.yap
+++ b/library/lineutils.yap
@@ -64,6 +64,21 @@ available by loading the
 :- use_module(library(readutil),
 	      [read_line_to_codes/2]).
 
+re_open(S, Mode, S) :-
+	is_stream(S),
+	!,
+	current_stream(_, Mode, S).
+re_open(F, Mode, S) :-
+	open(F, Mode, S).
+
+re_open(S, Mode, S, Props) :-
+	is_stream(S),
+	!,
+	current_stream(_, Mode, S),
+	maplist( set_stream(S), Props).
+re_open(F, Mode, S, Props) :-
+	open(F, Mode, S, Props).
+
 /**
  @pred search_for(+ _Char_,+ _Line_)
   Search for a character  _Char_ in the list of codes  _Line_.
@@ -454,8 +469,8 @@ process(StreamInp, Command) :-
   the output stream is accessible through `filter_output`.
 */
 file_filter(Inp, Out, Command) :-
-	open(Inp, read, StreamInp, [alias(filter_input)]),
-	open(Out, write, StreamOut),
+	re_open(Inp, read, StreamInp, [alias(filter_input)]),
+	re_open(Out, write, StreamOut),
 	filter(StreamInp, StreamOut, Command),
 	close(StreamInp),
 	close(StreamOut).
@@ -467,8 +482,8 @@ Same as file_filter/3, but before starting the filter execute
  _Arguments_.
 */
 file_filter_with_initialization(Inp, Out, Command, FormatString, Parameters) :-
-	open(Inp, read, StreamInp, [alias(filter_input)]),
-	open(Out, write, StreamOut, [alias(filter_output)]),
+	re_open(Inp, read, StreamInp, [alias(filter_input)]),
+	re_open(Out, write, StreamOut, [alias(filter_output)]),
 	format(StreamOut, FormatString, Parameters),
 	filter(StreamInp, StreamOut, Command),
 	close(StreamInp),
@@ -483,8 +498,8 @@ _StartGoal_,  and call _ENdGoal_ as an epilog.
 The input stream are always accessible through `filter_output` and `filter_input`.
 */
 file_filter_with_start_end(Inp, Out, Command, StartGoal, EndGoal) :-
-	open(Inp, read, StreamInp, [alias(filter_input)]),
-	open(Out, write, StreamOut, [alias(filter_output)]),
+	re_open(Inp, read, StreamInp, [alias(filter_input)]),
+	re_open(Out, write, StreamOut, [alias(filter_output)]),
 	call( StartGoal, StreamInp, StreamOut ),
 	filter(StreamInp, StreamOut, Command),
 	call( EndGoal, StreamInp, StreamOut ),
@@ -495,22 +510,22 @@ file_filter_with_start_end(Inp, Out, Command, StartGoal, EndGoal) :-
 /**
   * @pred file_select(+ _FileIn_, + _Goal_)  is meta
   *
-  * @param _FileIn_  File to process
+  * @param _FileIn_  File or Stream to process
   * @param _Goal_ to be metacalled, receives FileIn as
   * extra arguments
   *
   * @return  bindings to arguments of _Goal_.
-
-  For every line  _LineIn_ in file  _FileIn_, execute
-  `call(`Goal,LineIn)`.
-
-  The input stream is accessible through the alias `filter_input`, and
-  the output stream is accessible through `filter_output`.
+  *
+  * @brief For every line  _LineIn_ in file  _FileIn_, execute
+  * `call(`Goal,LineIn)`.
+  *
+  * The input stream is accessible through the alias `filter_input`, and
+  * the output stream is accessible through `filter_output`.
 */
 file_select(Inp, Command) :-
 	( retract(alias(F)) -> true ; F = '' ),
 	atom_concat(filter_input, F, Alias),
-        open(Inp, read, StreamInp, [Alias]),
+        re_open(Inp, read, StreamInp, [Alias]),
 	atom_concat('_', F, NF),
 	assert( alias(NF) ),
 	repeat,