From 3ca14ef7eab62f51ddacc8b22c19f3a7c8b96367 Mon Sep 17 00:00:00 2001
From: Uwe Dauernheim <uwe@klarna.com>
Date: Fri, 6 Jan 2012 19:18:05 +0100
Subject: [PATCH] Redirect output to stderr where appropriate

---
 lib/asn1/src/asn1ct.erl                   | 20 ++++++-----
 lib/asn1/src/asn1ct_check.erl             | 34 +++++++++++--------
 lib/asn1/src/asn1ct_gen.erl               |  2 +-
 lib/asn1/src/asn1ct_tok.erl               |  5 +--
 lib/common_test/src/ct_framework.erl      |  6 ++--
 lib/common_test/src/ct_logs.erl           | 41 +++++++++++++----------
 lib/common_test/src/ct_make.erl           |  6 ++--
 lib/common_test/src/ct_master.erl         | 20 +++++++----
 lib/common_test/src/ct_repeat.erl         | 12 ++++---
 lib/common_test/src/ct_run.erl            | 27 +++++++++------
 lib/common_test/src/ct_telnet_client.erl  |  2 +-
 lib/common_test/src/ct_util.erl           |  4 +--
 lib/common_test/src/vts.erl               |  4 +--
 lib/compiler/src/beam_clean.erl           |  3 +-
 lib/compiler/src/beam_validator.erl       |  2 +-
 lib/compiler/src/compile.erl              | 12 +++----
 lib/compiler/src/sys_pre_attributes.erl   |  4 +--
 lib/dialyzer/src/dialyzer.erl             |  2 +-
 lib/edoc/src/edoc.erl                     |  4 +--
 lib/edoc/src/edoc_report.erl              | 27 ++++++++++++---
 lib/eunit/src/eunit_server.erl            |  5 +--
 lib/eunit/src/eunit_tty.erl               | 16 ++++-----
 lib/hipe/cerl/cerl_cconv.erl              |  2 +-
 lib/hipe/icode/hipe_icode_type.erl        |  6 ++--
 lib/ic/src/ic.erl                         | 10 +++---
 lib/ic/src/ic_error.erl                   | 10 +++---
 lib/ic/src/ic_jbe.erl                     |  3 +-
 lib/ic/src/ic_pp.erl                      | 12 +++----
 lib/ic/src/ic_pragma.erl                  | 34 +++++++++----------
 lib/ic/src/icstruct.erl                   |  3 +-
 lib/ic/src/ictype.erl                     |  2 +-
 lib/parsetools/src/leex.erl               |  8 ++---
 lib/parsetools/src/yecc.erl               | 13 +++----
 lib/parsetools/src/yeccscan.erl           |  3 +-
 lib/reltool/src/reltool.erl               |  3 +-
 lib/reltool/src/reltool_sys_win.erl       | 11 +++---
 lib/sasl/src/systools.erl                 |  4 +--
 lib/sasl/src/systools_make.erl            |  8 ++---
 lib/sasl/src/systools_relup.erl           |  8 ++---
 lib/snmp/src/agent/snmpa_error_io.erl     |  2 +-
 lib/snmp/src/compile/snmpc.erl            |  2 +-
 lib/snmp/src/compile/snmpc_lib.erl        | 13 +++----
 lib/snmp/src/compile/snmpc_mib_to_hrl.erl |  2 +-
 lib/stdlib/src/c.erl                      | 21 +++++++-----
 lib/stdlib/src/epp.erl                    |  2 +-
 lib/stdlib/src/erl_compile.erl            | 19 ++++++-----
 lib/stdlib/src/escript.erl                | 22 ++++++------
 lib/stdlib/src/shell.erl                  |  7 +++-
 lib/test_server/src/test_server.erl       | 33 +++++++++++-------
 lib/test_server/src/test_server_ctrl.erl  | 28 +++++++++-------
 lib/test_server/src/ts_reports.erl        | 14 ++++----
 lib/test_server/src/ts_run.erl            |  8 ++---
 lib/tools/src/cover.erl                   | 10 +++---
 lib/tools/src/make.erl                    |  6 ++--
 lib/tools/src/xref_base.erl               | 11 +++---
 55 files changed, 344 insertions(+), 254 deletions(-)

diff --git a/lib/asn1/src/asn1ct.erl b/lib/asn1/src/asn1ct.erl
index 85bb5b2f28c4..0ce51e72848c 100644
--- a/lib/asn1/src/asn1ct.erl
+++ b/lib/asn1/src/asn1ct.erl
@@ -87,7 +87,9 @@ compile(File) ->
 compile(File,Options) when is_list(Options) ->
     case lists:member(driver, Options) of %% remove me in R16A!
 	true ->
-	    io:format("Warning: driver option is obsolete and will be removed in R16A, use nif instead!");
+	    io:format(standard_error,
+		    "Warning: driver option is obsolete "
+		    "and will be removed in R16A, use nif instead!");
 	false ->
 	    ok
     end,
@@ -1460,18 +1462,18 @@ vsn() ->
 
 
 print_error_message([got,H|T]) when is_list(H) ->
-    io:format(" got:"),
+    io:format(standard_error, " got:"),
     print_listing(H,"and"),
     print_error_message(T);
 print_error_message([expected,H|T]) when is_list(H) ->
-    io:format(" expected one of:"),
+    io:format(standard_error, " expected one of:"),
     print_listing(H,"or"),
     print_error_message(T);
 print_error_message([H|T])  ->
-    io:format(" ~p",[H]),
+    io:format(standard_error, " ~p",[H]),
     print_error_message(T);
 print_error_message([]) ->
-    io:format("~n").
+    io:format(standard_error, "~n").
 
 print_listing([H1,H2|[]],AndOr) ->
     io:format(" ~p ~s ~p",[H1,AndOr,H2]);
@@ -2544,7 +2546,7 @@ type_check(#'Externaltypereference'{}) ->
 error(Format, Args, S) ->
     case is_error(S) of
 	true ->
-	    io:format(Format, Args);
+	    io:format(standard_error, Format, Args);
 	false ->
 	    ok
     end.
@@ -2552,7 +2554,7 @@ error(Format, Args, S) ->
 warning(Format, Args, S) ->
     case is_warning(S) of
 	true ->
-	    io:format("Warning: " ++ Format, Args);
+	    io:format(standard_error, "Warning: " ++ Format, Args);
 	false ->
 	    ok
     end.
@@ -2560,10 +2562,10 @@ warning(Format, Args, S) ->
 warning(Format, Args, S, Reason) ->
     case {is_werr(S), is_error(S), is_warning(S)} of
 	{true, true, _} ->
-	    io:format(Format, Args),
+	    io:format(standard_error, Format, Args),
 	    throw({error, Reason});
 	{false, _, true} ->
-	    io:format(Format, Args);
+	    io:format(standard_error, Format, Args);
 	_ ->
 	    ok
     end.
diff --git a/lib/asn1/src/asn1ct_check.erl b/lib/asn1/src/asn1ct_check.erl
index e31847723472..0c695afdf689 100644
--- a/lib/asn1/src/asn1ct_check.erl
+++ b/lib/asn1/src/asn1ct_check.erl
@@ -4241,7 +4241,7 @@ check_constraint(S,{simpletable,Type}) ->
 	    ObjSet = GetObjectSet(TorVDef),
 	    {simpletable,check_object(S,Type,ObjSet)};
 	#'ObjectSet'{} ->
-	    io:format("ALERT: simpletable forbidden case!~n",[]),
+	    io:format(standard_error, "ALERT: simpletable forbidden case!~n",[]),
 	    {simpletable,check_object(S,Type,C)};
 	{'ValueFromObject',{_,ORef},FieldName} ->
 	    %% This is an ObjectFromObject
@@ -7153,7 +7153,7 @@ findtypes_and_values([],Tacc,Vacc,Pacc,Cacc,Oacc,OSacc) ->
 
 error({export,Msg,#state{mname=Mname,type=Ref,tname=Typename}}) ->
     Pos = Ref#'Externaltypereference'.pos,
-    io:format("asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
     {error,{export,Pos,Mname,Typename,Msg}};
 error({import,Msg,#state{mname=Mname,type=Ref,tname=Typename}}) ->
     PosOfDef =
@@ -7161,52 +7161,58 @@ error({import,Msg,#state{mname=Mname,type=Ref,tname=Typename}}) ->
 	   (#'Externalvaluereference'{pos=P}) -> P
 	end,
     Pos = PosOfDef(Ref),
-    io:format("asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
     {error,{import,Pos,Mname,Typename,Msg}};
 % error({type,{Msg1,Msg2},#state{mname=Mname,type=Type,tname=Typename}}) 
 %   when is_record(Type,typedef) ->
-%     io:format("asn1error:~p:~p:~p ~p~n",
+%     io:format(standard_error, "asn1error:~p:~p:~p ~p~n",
 % 	      [Type#typedef.pos,Mname,Typename,Msg1]),
 %     {error,{type,Type#typedef.pos,Mname,Typename,Msg1,Msg2}};
 error({type,Msg,#state{mname=Mname,type=Type,tname=Typename}}) 
   when is_record(Type,type) ->
-    io:format("asn1error:~p:~p~n~p~n",
+    io:format(standard_error, "asn1error:~p:~p~n~p~n",
 	      [Mname,Typename,Msg]),
     {error,{type,Mname,Typename,Msg}};
 error({type,Msg,#state{mname=Mname,type=Type,tname=Typename}}) 
   when is_record(Type,typedef) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
 	      [Type#typedef.pos,Mname,Typename,Msg]),
     {error,{type,Type#typedef.pos,Mname,Typename,Msg}};
 error({type,Msg,#state{mname=Mname,type=Type,tname=Typename}}) 
   when is_record(Type,ptypedef) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
 	      [Type#ptypedef.pos,Mname,Typename,Msg]),
     {error,{type,Type#ptypedef.pos,Mname,Typename,Msg}};
 error({type,Msg,#state{mname=Mname,value=Value,vname=Valuename}})
   when is_record(Value,valuedef) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[Value#valuedef.pos,Mname,Valuename,Msg]),
+    io:format(standard_error,"asn1error:~p:~p:~p~n~p~n",
+              [Value#valuedef.pos,Mname,Valuename,Msg]),
     {error,{type,Value#valuedef.pos,Mname,Valuename,Msg}};
 error({type,Msg,#state{mname=Mname,type=Type,tname=Typename}}) 
   when is_record(Type,pobjectdef) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
 	      [Type#pobjectdef.pos,Mname,Typename,Msg]),
     {error,{type,Type#pobjectdef.pos,Mname,Typename,Msg}};
 error({value,Msg,#state{mname=Mname,value=Value,vname=Valuename}}) 
   when is_record(Value,valuedef) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[Value#valuedef.pos,Mname,Valuename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
+              [Value#valuedef.pos,Mname,Valuename,Msg]),
     {error,{value,Value#valuedef.pos,Mname,Valuename,Msg}};
 error({Other,Msg,#state{mname=Mname,value=#valuedef{pos=Pos},vname=Valuename}}) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Valuename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
+              [Pos,Mname,Valuename,Msg]),
     {error,{Other,Pos,Mname,Valuename,Msg}};
 error({Other,Msg,#state{mname=Mname,type=#typedef{pos=Pos},tname=Typename}}) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
+              [Pos,Mname,Typename,Msg]),
     {error,{Other,Pos,Mname,Typename,Msg}};
 error({Other,Msg,#state{mname=Mname,type=#classdef{pos=Pos},tname=Typename}}) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[Pos,Mname,Typename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
+              [Pos,Mname,Typename,Msg]),
     {error,{Other,Pos,Mname,Typename,Msg}};
 error({Other,Msg,#state{mname=Mname,type=Type,tname=Typename}}) ->
-    io:format("asn1error:~p:~p:~p~n~p~n",[asn1ct:get_pos_of_def(Type),Mname,Typename,Msg]),
+    io:format(standard_error, "asn1error:~p:~p:~p~n~p~n",
+              [asn1ct:get_pos_of_def(Type),Mname,Typename,Msg]),
     {error,{Other,asn1ct:get_pos_of_def(Type),Mname,Typename,Msg}}.
 
 include_default_type(Module) ->
diff --git a/lib/asn1/src/asn1ct_gen.erl b/lib/asn1/src/asn1ct_gen.erl
index 0f8833f71673..c5d47a24fc58 100644
--- a/lib/asn1/src/asn1ct_gen.erl
+++ b/lib/asn1/src/asn1ct_gen.erl
@@ -1308,7 +1308,7 @@ fopen(F, ModeList) ->
 	{ok, Fd} -> 
 	    Fd;
 	{error, Reason} ->
-	    io:format("** Can't open file ~p ~n", [F]),
+	    io:format(standard_error, "** Can't open file ~p ~n", [F]),
 	    exit({error,Reason})
     end.
 
diff --git a/lib/asn1/src/asn1ct_tok.erl b/lib/asn1/src/asn1ct_tok.erl
index 85199c65ecff..adbfcbcfeb81 100644
--- a/lib/asn1/src/asn1ct_tok.erl
+++ b/lib/asn1/src/asn1ct_tok.erl
@@ -44,7 +44,8 @@ process(L, Stream,Lno,R) when is_list(L) ->
     %%io:format('read:~s',[L]),
     case catch tokenise(Stream,L,Lno,[]) of
 	{'ERR',Reason} ->
-	    io:format("Tokeniser error on line: ~w ~w~n",[Lno,Reason]),
+	    io:format(standard_error,
+		    "Tokeniser error on line: ~w ~w~n",[Lno,Reason]),
 	    exit(0);
 	{NewLno,T} ->
 	    %%io:format('toks:~w~n',[T]),
@@ -249,7 +250,7 @@ skip_comment([_|T]) ->
 skip_multiline_comment(Stream,[],Lno,Level) ->
     case io:get_line(Stream,'') of
 	eof ->
-	    io:format("Tokeniser error on line: ~w~n"
+	    io:format(standard_error, "Tokeniser error on line: ~w~n"
 		      "premature end of multiline comment~n",[Lno]),
 	    exit(0);
 	Line ->
diff --git a/lib/common_test/src/ct_framework.erl b/lib/common_test/src/ct_framework.erl
index c24a7c238bd2..615f8c2541ac 100644
--- a/lib/common_test/src/ct_framework.erl
+++ b/lib/common_test/src/ct_framework.erl
@@ -280,7 +280,7 @@ add_defaults(Mod,Func, GroupPath, DoInit) ->
 	    ErrStr = io_lib:format("~n*** ERROR *** "
 				   "~w:suite/0 failed: ~p~n",
 				   [Suite,Reason]),
-	    io:format(ErrStr, []),
+	    io:format(standard_error, ErrStr, []),
 	    io:format(user, ErrStr, []),
 	    {suite0_failed,{exited,Reason}};
 	SuiteInfo when is_list(SuiteInfo) ->
@@ -300,7 +300,7 @@ add_defaults(Mod,Func, GroupPath, DoInit) ->
 		    ErrStr = io_lib:format("~n*** ERROR *** "
 					   "Invalid return value from "
 					   "~w:suite/0: ~p~n", [Suite,SuiteInfo]),
-		    io:format(ErrStr, []),
+		    io:format(standard_error, ErrStr, []),
 		    io:format(user, ErrStr, []),
 		    {suite0_failed,bad_return_value}
 	    end;
@@ -308,7 +308,7 @@ add_defaults(Mod,Func, GroupPath, DoInit) ->
 	    ErrStr = io_lib:format("~n*** ERROR *** "
 				   "Invalid return value from "
 				   "~w:suite/0: ~p~n", [Suite,SuiteInfo]),
-	    io:format(ErrStr, []),
+	    io:format(standard_error, ErrStr, []),
 	    io:format(user, ErrStr, []),
 	    {suite0_failed,bad_return_value}
     end.
diff --git a/lib/common_test/src/ct_logs.erl b/lib/common_test/src/ct_logs.erl
index 19ad7b26d83d..66a4db275d24 100644
--- a/lib/common_test/src/ct_logs.erl
+++ b/lib/common_test/src/ct_logs.erl
@@ -126,7 +126,7 @@ close(Info, StartDir) ->
 		ok ->
 		    ok;
 		Error ->
-		    io:format("Warning! Cleanup failed: ~p~n", [Error])
+		    io:format(standard_error, "Warning! Cleanup failed: ~p~n", [Error])
 	    end,
 	    make_all_suites_index(stop),
 	    make_all_runs_index(stop);
@@ -787,18 +787,20 @@ make_last_run_index(StartTime) ->
     AbsIndexName = ?abs(IndexName),
     case catch make_last_run_index1(StartTime,IndexName) of
 	{'EXIT', Reason} ->
-	    io:put_chars("CRASHED while updating " ++ AbsIndexName ++ "!\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error,
+	                 "CRASHED while updating " ++ AbsIndexName ++ "!\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	{error, Reason} ->
-	    io:put_chars("FAILED while updating " ++ AbsIndexName ++ "\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error,
+	                 "FAILED while updating " ++ AbsIndexName ++ "\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	ok ->
 %	    io:put_chars("done\n"),
 	    ok;
 	Err ->
-	    io:format("Unknown internal error while updating ~s. "
+	    io:format(standard_error, "Unknown internal error while updating ~s. "
 		      "Please report.\n(Err: ~p, ID: 1)",
 		      [AbsIndexName,Err]),
 	    {error, Err}
@@ -1264,7 +1266,8 @@ count_cases(Dir) ->
 			    Summary
 		    end;
 		{error, _Reason} ->
-		    io:format("\nFailed to read ~p (skipped)\n", [LogFile]),
+		    io:format(standard_error,
+			    "\nFailed to read ~p (skipped)\n", [LogFile]),
 		    error
 	    end
     end.
@@ -1612,17 +1615,19 @@ make_all_suites_index(NewTestData = {_TestName,DirName}) ->
 					     Label,
 					     LogDirData) of
 	    {'EXIT',Reason} ->
-		io:put_chars("CRASHED while updating " ++ AbsIndexName ++ "!\n"),
-		io:format("~p~n", [Reason]),
+		io:put_chars(standard_error,
+		             "CRASHED while updating " ++ AbsIndexName ++ "!\n"),
+		io:format(standard_error, "~p~n", [Reason]),
 		{error,Reason};
 	    {error,Reason} ->
-		io:put_chars("FAILED while updating " ++ AbsIndexName ++ "\n"),
-		io:format("~p~n", [Reason]),
+		io:put_chars(standard_error,
+		             "FAILED while updating " ++ AbsIndexName ++ "\n"),
+		io:format(standard_error, "~p~n", [Reason]),
 		{error,Reason};
 	    ok ->
 		ok;
 	    Err ->
-		io:format("Unknown internal error while updating ~s. "
+		io:format(standard_error, "Unknown internal error while updating ~s. "
 			  "Please report.\n(Err: ~p, ID: 1)",
 			  [AbsIndexName,Err]),
 		{error, Err}
@@ -1662,12 +1667,14 @@ make_all_suites_index1(When, AbsIndexName, AllLogDirs) ->
     end,
     case catch make_all_suites_index2(IndexName, AllLogDirs) of
 	{'EXIT', Reason} ->
-	    io:put_chars("CRASHED while updating " ++ AbsIndexName ++ "!\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error,
+		             "CRASHED while updating " ++ AbsIndexName ++ "!\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	{error, Reason} ->
-	    io:put_chars("FAILED while updating " ++ AbsIndexName ++ "\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error,
+		             "FAILED while updating " ++ AbsIndexName ++ "\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	{ok,CacheData} ->
 	    case When of
@@ -1680,7 +1687,7 @@ make_all_suites_index1(When, AbsIndexName, AllLogDirs) ->
 		    ok
 	    end;
 	Err ->
-	    io:format("Unknown internal error while updating ~s. "
+	    io:format(standard_error, "Unknown internal error while updating ~s. "
 		      "Please report.\n(Err: ~p, ID: 1)",
 		      [AbsIndexName,Err]),
 	    {error, Err}
diff --git a/lib/common_test/src/ct_make.erl b/lib/common_test/src/ct_make.erl
index 8ddb91d35543..1fb8f015ae09 100644
--- a/lib/common_test/src/ct_make.erl
+++ b/lib/common_test/src/ct_make.erl
@@ -95,7 +95,8 @@ read_emakefile(Emakefile,Opts) ->
 	    Mods = [filename:rootname(F) ||  F <- filelib:wildcard("*.erl")],
 	    [{Mods, Opts}];
 	{error,Other} ->
-	    io:format("make: Trouble reading 'Emakefile':~n~p~n",[Other]),
+	    io:format(standard_error,
+		    "make: Trouble reading 'Emakefile':~n~p~n",[Other]),
 	    error
     end.
 
@@ -150,7 +151,8 @@ get_opts_from_emakefile(Mods,Emakefile,Opts) ->
 	{error,enoent} ->
 	    [{Mods, Opts}];
 	{error,Other} ->
-	    io:format("make: Trouble reading 'Emakefile':~n~p~n",[Other]),
+	    io:format(standard_error,
+		    "make: Trouble reading 'Emakefile':~n~p~n",[Other]),
 	    error
     end.
 
diff --git a/lib/common_test/src/ct_master.erl b/lib/common_test/src/ct_master.erl
index 2ea2ba106a04..63c247adaad4 100644
--- a/lib/common_test/src/ct_master.erl
+++ b/lib/common_test/src/ct_master.erl
@@ -298,7 +298,7 @@ init_master(Parent,NodeOptsList,EvHandlers,MasterLogDir,LogDirs,InitOptions,Spec
 	    register(ct_master,self()),
 	    ok;
 	_Pid ->
-	    io:format("~nWarning: ct_master already running!~n"),
+	    io:format(standard_error, "~nWarning: ct_master already running!~n"),
 	    exit(aborted)
 %	    case io:get_line('[y/n]>') of
 %		"y\n" ->
@@ -660,7 +660,8 @@ init_node_ctrl(MasterPid,Cookie,Opts) ->
 	pong ->
 	    MasterPid ! {self(),{result,Result}};
 	pang ->
-	    io:format("Warning! Connection to master node ~p is lost. "
+	    io:format(standard_error,
+		      "Warning! Connection to master node ~p is lost. "
 		      "Can't report result!~n~n", [MasterNode])
     end.
 
@@ -740,7 +741,8 @@ start_nodes(InitOptions)->
 	IsAlive = lists:member(NodeName, nodes()),
 	case {HasNodeStart, IsAlive} of
 	    {false, false}->
-		io:format("WARNING: Node ~p is not alive but has no node_start option~n", [NodeName]);
+		io:format(standard_error,
+		    "WARNING: Node ~p is not alive but has no node_start option~n", [NodeName]);
 	    {false, true}->
 		io:format("Node ~p is alive~n", [NodeName]);
 	    {true, false}->
@@ -751,10 +753,12 @@ start_nodes(InitOptions)->
 		    {ok, NodeName} ->
 			io:format("Node ~p started successfully with callback ~p~n", [NodeName,Callback]);
 		    {error, Reason, _NodeName} ->
-			io:format("Failed to start node ~p with callback ~p! Reason: ~p~n", [NodeName, Callback, Reason])
+			io:format(standard_error,
+				"Failed to start node ~p with callback ~p! Reason: ~p~n", [NodeName, Callback, Reason])
 		end;
 	    {true, true}->
-		io:format("WARNING: Node ~p is alive but has node_start option~n", [NodeName])
+		io:format(standard_error,
+			"WARNING: Node ~p is alive but has node_start option~n", [NodeName])
 	end
     end,
     InitOptions).
@@ -767,7 +771,8 @@ eval_on_nodes(InitOptions)->
 	    {false,_}->
 		ok;
 	    {true,false}->
-		io:format("WARNING: Node ~p is not alive but has eval option ~n", [NodeName]);
+		io:format(standard_error,
+			"WARNING: Node ~p is not alive but has eval option ~n", [NodeName]);
 	    {true,true}->
 		{eval, MFAs} = lists:keyfind(eval, 1, Options),
 		evaluate(NodeName, MFAs)
@@ -778,7 +783,8 @@ eval_on_nodes(InitOptions)->
 evaluate(Node, [{M,F,A}|MFAs])->
     case rpc:call(Node, M, F, A) of
         {badrpc,Reason}->
-	    io:format("WARNING: Failed to call ~p:~p/~p on node ~p due to ~p~n", [M,F,length(A),Node,Reason]);
+	    io:format(standard_error,
+		    "WARNING: Failed to call ~p:~p/~p on node ~p due to ~p~n", [M,F,length(A),Node,Reason]);
 	Result->
 	    io:format("Called ~p:~p/~p on node ~p, result: ~p~n", [M,F,length(A),Node,Result])
     end,
diff --git a/lib/common_test/src/ct_repeat.erl b/lib/common_test/src/ct_repeat.erl
index be3c485b7553..a2623f2164a6 100644
--- a/lib/common_test/src/ct_repeat.erl
+++ b/lib/common_test/src/ct_repeat.erl
@@ -42,7 +42,7 @@ loop_test(If,Args) when is_list(Args) ->
 	no_loop ->
 	    false;
 	{error,E} ->
-	    io:format("Common Test error: ~p\n\n",[E]),
+	    io:format(standard_error, "Common Test error: ~p\n\n",[E]),
 	    file:set_cwd(Cwd),
 	    E;
 	{repeat,N} ->
@@ -79,25 +79,27 @@ loop(If,Type,N,Data0,Data1,Args,TPid) ->
     Pid = spawn_tester(If,self(),Args),
     receive 
 	{'EXIT',Pid,Reason} ->
-	    io:format("Test run crashed! This could be an internal error "
+	    io:format(standard_error,
+		      "Test run crashed! This could be an internal error "
 		      "- please report!\n\n"
 		      "~p\n\n",[Reason]),
 	    cancel(TPid),
 	    {error,Reason};
 	{Pid,{error,Reason}} ->
-	    io:format("\nTest run failed!\nReason: ~p\n\n",[Reason]),
+	    io:format(standard_error, "\nTest run failed!\nReason: ~p\n\n",[Reason]),
 	    cancel(TPid),
 	    {error,Reason};
 	{Pid,Result} ->
 	    if Type == repeat ->
-		    io:format("\nTest run ~w(~w) complete.\n\n",[N+1,Data0]),		    
+		    io:format("\nTest run ~w(~w) complete.\n\n",[N+1,Data0]),
 		    lists:keydelete(loop_info,1,Args),
 		    Args1 = [{loop_info,[{repeat,N+2,Data0}]} | Args],
 		    loop(If,repeat,N+1,Data0,Data1,Args1,TPid);
 	       Type == stop_time ->
 		    case remaining_time(Data1) of
 			0 ->
-			    io:format("\nTest time (~s) has run out.\n\n",[ts(Data0)]),
+			    io:format(standard_error,
+				      "\nTest time (~s) has run out.\n\n",[ts(Data0)]),
 			    cancel(TPid),
 			    Result;
 			Secs ->
diff --git a/lib/common_test/src/ct_run.erl b/lib/common_test/src/ct_run.erl
index 05b10bca3267..e13e5c423adf 100644
--- a/lib/common_test/src/ct_run.erl
+++ b/lib/common_test/src/ct_run.erl
@@ -140,16 +140,19 @@ script_start(Args) ->
 		    {'EXIT',Pid,Reason} ->
 			case Reason of
 			    {user_error,What} ->
-				io:format("\nTest run failed!\nReason: ~p\n\n", [What]),
+				io:format(standard_error,
+					  "\nTest run failed!\nReason: ~p\n\n", [What]),
 				{error,What};
 			    _ ->
-				io:format("Test run crashed! This could be an internal error "
+				io:format(standard_error, 
+					  "Test run crashed! This could be an internal error "
 					  "- please report!\n\n"
 					  "~p\n\n", [Reason]),
 				{error,Reason}				
 			end;
 		    {Pid,{error,Reason}} ->
-			io:format("\nTest run failed! Reason:\n~p\n\n",[Reason]),
+			io:format(standard_error,
+					  "\nTest run failed! Reason:\n~p\n\n",[Reason]),
 			{error,Reason};
 		    {Pid,Result} ->
 			Result
@@ -535,7 +538,7 @@ script_start4(#opts{vts = true, cover = Cover}, _) ->
 	    script_usage();
 	_ ->
 	    %% Add support later (maybe).
-	    io:format("\nCan't run cover in vts mode.\n\n", [])
+	    io:format(standard_error, "\nCan't run cover in vts mode.\n\n", [])
     end,
     erlang:halt();
 
@@ -545,7 +548,7 @@ script_start4(#opts{shell = true, cover = Cover}, _) ->
 	    script_usage();
 	_ ->
 	    %% Add support later (maybe).
-	    io:format("\nCan't run cover in interactive mode.\n\n", [])
+	    io:format(standard_error, "\nCan't run cover in interactive mode.\n\n", [])
     end;
 
 script_start4(Opts = #opts{tests = Tests}, Args) ->
@@ -649,13 +652,15 @@ install(Opts, LogDir) ->
 		    file:close(Fd),
 		    ok;
 		{error,Reason} ->
-		    io:format("CT failed to install configuration data. Please "
+		    io:format(standard_error,
+			      "CT failed to install configuration data. Please "
 			      "verify that the log directory exists and that "
 			      "write permission is set.\n\n", []),
 		    {error,{VarFile,Reason}}
 	    end;
 	_ ->
-	    io:format("It is not possible to install CT while running "
+	    io:format(standard_error,
+		      "It is not possible to install CT while running "
 		      "in interactive mode.\n"
 		      "To exit this mode, run ct:stop_interactive().\n"
 		      "To enter the interactive mode again, "
@@ -1721,7 +1726,7 @@ continue(_MakeErrors) ->
 		    R
 	    after 15000 ->
 		    exit(Pid, kill),
-		    io:format("... timeout - continuing!!\n"),
+		    io:format(standard_error, "... timeout - continuing!!\n"),
 		    true
 	    end;
 	false ->				% no shell process to use
@@ -2550,12 +2555,14 @@ start_trace(Args) ->
 			ok ->
 			    true;
 			{_,Error} ->
-			    io:format("Warning! Tracing not started. Reason: ~p~n~n",
+			    io:format(standard_error,
+				      "Warning! Tracing not started. Reason: ~p~n~n",
 				      [Error]),
 			    false
 		    end;
 		{_,Error} ->
-		    io:format("Warning! Tracing not started. Reason: ~s~n~n",
+		    io:format(standard_error,
+			      "Warning! Tracing not started. Reason: ~s~n~n",
 			      [file:format_error(Error)]),
 		    false
 	    end;
diff --git a/lib/common_test/src/ct_telnet_client.erl b/lib/common_test/src/ct_telnet_client.erl
index d703b39ac550..47be08ee27ba 100644
--- a/lib/common_test/src/ct_telnet_client.erl
+++ b/lib/common_test/src/ct_telnet_client.erl
@@ -310,7 +310,7 @@ cmd_dbg(_Cmd) ->
 		end,
 	    io:format("~s(~w): ~w\n", [CtrlStr,Ctrl,Opts1]);
 	Any  ->
-	    io:format("Unexpected in cmd_dbg:~n~w~n",[Any])
+	    io:format(standard_error, "Unexpected in cmd_dbg:~n~w~n",[Any])
     end.
 
 -else.
diff --git a/lib/common_test/src/ct_util.erl b/lib/common_test/src/ct_util.erl
index 3b6ad6f98d8a..68c719637fc8 100644
--- a/lib/common_test/src/ct_util.erl
+++ b/lib/common_test/src/ct_util.erl
@@ -370,7 +370,7 @@ loop(Mode,TestData,StartDir) ->
 	    loop(Mode,TestData,StartDir);
 	{'EXIT',Pid,Reason} ->
 	    %% Let process crash in case of error, this shouldn't happen!
-	    io:format("\n\nct_util_server got EXIT from ~p: ~p\n\n",
+	    io:format(standard_error, "\n\nct_util_server got EXIT from ~p: ~p\n\n",
 		      [Pid,Reason]),
 	    file:set_cwd(StartDir),
 	    exit(Reason)
@@ -907,7 +907,7 @@ open_url(iexplore, Args, URL) ->
 	    io:format(user, "~nOpening ~s with command:~n  ~s~n", [URL,Cmd1]),
 	    open_port({spawn,Cmd1}, []);
 	_ ->
-	    io:format("~nNo path to iexplore.exe~n",[])
+	    io:format(standard_error, "~nNo path to iexplore.exe~n",[])
     end,
     win32reg:close(R),
     ok;
diff --git a/lib/common_test/src/vts.erl b/lib/common_test/src/vts.erl
index cc8a9328874e..131f89b2d8b5 100644
--- a/lib/common_test/src/vts.erl
+++ b/lib/common_test/src/vts.erl
@@ -249,7 +249,7 @@ loop(State) ->
 	{'EXIT',Pid,Reason} ->
 	    case State#state.test_runner of
 		Pid ->
-		    io:format("Test run error: ~p\n",[Reason]),
+		    io:format(standard_error, "Test run error: ~p\n",[Reason]),
 		    loop(State);
 		_ ->
 		    loop(State)
@@ -551,7 +551,7 @@ case_select(Dir,Suite,Case,N) ->
 	    code:add_pathz(Dir),
 	    case catch apply(Suite,all,[]) of
 		{'EXIT',Reason} ->
-		    io:format("\n~p\n",[Reason]),
+		    io:format(standard_error, "\n~p\n",[Reason]),
 		    red(["COULD NOT READ TESTCASES!!",br(),
 			 "See erlang shell for info"]);
 		{skip,_Reason} ->
diff --git a/lib/compiler/src/beam_clean.erl b/lib/compiler/src/beam_clean.erl
index a7994ab3b3f2..d7f0a3a0ce69 100644
--- a/lib/compiler/src/beam_clean.erl
+++ b/lib/compiler/src/beam_clean.erl
@@ -181,7 +181,8 @@ function_replace([{function,Name,Arity,Entry,Asm0}|Fs], Dict, Acc) ->
 	      replace(Asm0, [], Dict)
 	  catch
 	      throw:{error,{undefined_label,Lbl}=Reason} ->
-		  io:format("Function ~s/~w refers to undefined label ~w\n",
+		  io:format(standard_error,
+			    "Function ~s/~w refers to undefined label ~w\n",
 			    [Name,Arity,Lbl]),
 		  exit(Reason)
 	  end,
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index a52e7bb76198..8c527d0a9d9a 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -62,7 +62,7 @@ files([F|Fs]) ->
     case file(F) of
 	ok -> ok;
 	{error,Es} -> 
-	    io:format("~p:~n~s~n", [F,format_error(Es)])
+	    io:format(standard_error, "~p:~n~s~n", [F,format_error(Es)])
     end,
     files(Fs);
 files([]) -> ok.
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 9b505ad15c10..c3d540fd105f 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -135,11 +135,11 @@ env_default_opts() ->
 			{ok,List} when is_list(List) -> List;
 			{ok,Term} -> [Term];
 			{error,_Reason} ->
-			    io:format("Ignoring bad term in ~s\n", [Key]),
+			    io:format(standard_error, "Ignoring bad term in ~s\n", [Key]),
 			    []
 		    end;
 		{error, {_,_,_Reason}, _} ->
-		    io:format("Ignoring bad term in ~s\n", [Key]),
+		    io:format(standard_error, "Ignoring bad term in ~s\n", [Key]),
 		    []
 	    end
     end.
@@ -1414,7 +1414,7 @@ report_warnings(#compile{options=Opts,warnings=Ws0}) ->
 			     ({F,Eds}) -> format_message(F, P, Eds) end,
 			  Ws0),
 	    Ws = lists:sort(Ws1),
-	    foreach(fun({_,Str}) -> io:put_chars(Str) end, Ws);
+	    foreach(fun({_,Str}) -> io:put_chars(standard_error, Str) end, Ws);
 	false -> ok
     end.
 
@@ -1434,13 +1434,13 @@ format_message(_, _, []) -> [].
 %% list_errors(File, ErrorDescriptors) -> ok
 
 list_errors(F, [{{Line,Column},Mod,E}|Es]) ->
-    io:fwrite("~s:~w:~w: ~s\n", [F,Line,Column,Mod:format_error(E)]),
+    io:fwrite(standard_error, "~s:~w:~w: ~s\n", [F,Line,Column,Mod:format_error(E)]),
     list_errors(F, Es);
 list_errors(F, [{Line,Mod,E}|Es]) ->
-    io:fwrite("~s:~w: ~s\n", [F,Line,Mod:format_error(E)]),
+    io:fwrite(standard_error, "~s:~w: ~s\n", [F,Line,Mod:format_error(E)]),
     list_errors(F, Es);
 list_errors(F, [{Mod,E}|Es]) ->
-    io:fwrite("~s: ~s\n", [F,Mod:format_error(E)]),
+    io:fwrite(standard_error, "~s: ~s\n", [F,Mod:format_error(E)]),
     list_errors(F, Es);
 list_errors(_F, []) -> ok.
 
diff --git a/lib/compiler/src/sys_pre_attributes.erl b/lib/compiler/src/sys_pre_attributes.erl
index a6b7274b0702..14354ee3e91b 100644
--- a/lib/compiler/src/sys_pre_attributes.erl
+++ b/lib/compiler/src/sys_pre_attributes.erl
@@ -182,7 +182,7 @@ attrs([], _, _) ->
 report_error(Format, Args, S) -> 
     case is_error(S) of
 	true ->
-	    io:format("~p: * ERROR * " ++ Format, [?MODULE | Args]);
+	    io:format(standard_error, "~p: * ERROR * " ++ Format, [?MODULE | Args]);
 	false ->
 	    ok
     end.
@@ -190,7 +190,7 @@ report_error(Format, Args, S) ->
 report_warning(Format, Args, S) -> 
     case is_warning(S) of
 	true ->
-	    io:format("~p: * WARNING * " ++ Format, [?MODULE | Args]);
+	    io:format(standard_error, "~p: * WARNING * " ++ Format, [?MODULE | Args]);
 	false ->
 	    ok
     end.
diff --git a/lib/dialyzer/src/dialyzer.erl b/lib/dialyzer/src/dialyzer.erl
index 3e3c12405f62..7444addd746c 100644
--- a/lib/dialyzer/src/dialyzer.erl
+++ b/lib/dialyzer/src/dialyzer.erl
@@ -271,7 +271,7 @@ cl_halt({ok, R = ?RET_DISCREPANCIES}, #options{output_file = Output}) ->
   halt(R);
 cl_halt({error, Msg1}, #options{output_file = Output}) ->
   %% Msg2 = "dialyzer: Internal problems were encountered in the analysis",
-  io:format("\ndialyzer: ~s\n", [Msg1]),
+  io:format(standard_error, "\ndialyzer: ~s\n", [Msg1]),
   cl_check_log(Output),
   halt(?RET_INTERNAL_ERROR).
 
diff --git a/lib/edoc/src/edoc.erl b/lib/edoc/src/edoc.erl
index 544465b14a50..740dce2bbb4d 100644
--- a/lib/edoc/src/edoc.erl
+++ b/lib/edoc/src/edoc.erl
@@ -175,7 +175,7 @@ application(App, Options) when is_atom(App) ->
  	Dir when is_list(Dir) ->
  	    application(App, Dir, Options);
  	_ ->
-	    edoc_report:report("cannot find application directory for '~s'.",
+	    edoc_report:report_error("cannot find application directory for '~s'.",
                                [App]),
  	    exit(error)
     end.
@@ -686,7 +686,7 @@ check_forms(Fs, Name) ->
 			 {L, M, D} ->
 			     edoc_report:error(L, Name, {format_error, M, D});
 			 Other ->
-			     edoc_report:report(Name, "unknown error in "
+			     edoc_report:report_error(Name, "unknown error in "
                                                 "source code: ~w.", [Other])
 		     end,
 		     exit(error);
diff --git a/lib/edoc/src/edoc_report.erl b/lib/edoc/src/edoc_report.erl
index 9bec08ab973d..ca4d0b54be6f 100644
--- a/lib/edoc/src/edoc_report.erl
+++ b/lib/edoc/src/edoc_report.erl
@@ -33,6 +33,9 @@
 	 report/2,
 	 report/3,
 	 report/4,
+	 report_error/2,
+	 report_error/3,
+	 report_error/4,
 	 warning/1,
 	 warning/2,
 	 warning/3,
@@ -48,11 +51,11 @@ error(Where, What) ->
     error(0, Where, What).
 
 error(Line, Where, S) when is_list(S) ->
-    report(Line, Where, S, []);
+    report_error(Line, Where, S, []);
 error(Line, Where, {S, D}) when is_list(S) ->
-    report(Line, Where, S, D);
+    report_error(Line, Where, S, D);
 error(Line, Where, {format_error, M, D}) ->
-    report(Line, Where, M:format_error(D), []).
+    report_error(Line, Where, M:format_error(D), []).
 
 warning(S) ->
     warning(S, []).
@@ -64,7 +67,7 @@ warning(Where, S, Vs) ->
     warning(0, Where, S, Vs).
 
 warning(L, Where, S, Vs) ->
-    report(L, Where, "warning: " ++ S, Vs).
+    report_error(L, Where, "warning: " ++ S, Vs).
 
 report(S, Vs) ->
     report([], S, Vs).
@@ -82,6 +85,22 @@ report(L, Where, S, Vs) ->
     io:fwrite(S, Vs),
     io:nl().
 
+report_error(S, Vs) ->
+    report_error([], S, Vs).
+
+report_error(Where, S, Vs) ->
+    report_error(0, Where, S, Vs).
+
+report_error(L, Where, S, Vs) ->
+    io:put_chars(standard_error, where(Where)),
+    if is_integer(L), L > 0 ->
+	    io:fwrite(standard_error, "at line ~w: ", [L]);
+       true ->
+	    ok
+    end,
+    io:fwrite(standard_error, S, Vs),
+    io:nl(standard_error).
+
 where({File, module}) ->
     io_lib:fwrite("~s, in module header: ", [File]);
 where({File, footer}) ->
diff --git a/lib/eunit/src/eunit_server.erl b/lib/eunit/src/eunit_server.erl
index 2002930abb59..d369a03baff2 100644
--- a/lib/eunit/src/eunit_server.erl
+++ b/lib/eunit/src/eunit_server.erl
@@ -325,8 +325,9 @@ auto_super(Server, M) ->
 	    ok
     after ?AUTO_TIMEOUT	->
 	    exit(Pid, kill),
-	    io:put_chars("\n== EUnit: automatic test was aborted ==\n"),
-	    io:put_chars("\n> ")
+	    io:put_chars(standard_error,
+	                 "\n== EUnit: automatic test was aborted ==\n"),
+	    io:put_chars(standard_error, "\n> ")
     end,
     Server ! {done, auto_test, self()}.
 
diff --git a/lib/eunit/src/eunit_tty.erl b/lib/eunit/src/eunit_tty.erl
index e3e7b710b21e..333af0f608f3 100644
--- a/lib/eunit/src/eunit_tty.erl
+++ b/lib/eunit/src/eunit_tty.erl
@@ -82,7 +82,7 @@ terminate({ok, Data}, St) ->
 	    sync_end(error)
     end;
 terminate({error, Reason}, _St) ->
-    io:fwrite("Internal error: ~P.\n", [Reason, 25]),
+    io:fwrite(standard_error, "Internal error: ~P.\n", [Reason, 25]),
     sync_end(error).
 
 sync_end(Result) ->
@@ -212,18 +212,18 @@ print_test_end(Data) ->
 
 print_test_error({error, Exception}, Data) ->
     Output = proplists:get_value(output, Data),
-    io:fwrite("*failed*\n::~s",
+    io:fwrite(standard_error, "*failed*\n::~s",
 	      [eunit_lib:format_exception(Exception)]),
     case Output of
 	<<>> ->
-	    io:put_chars("\n\n");
+	    io:put_chars(standard_error, "\n\n");
 	<<Text:800/binary, _:1/binary, _/binary>> ->
-	    io:fwrite("  output:<<\"~s\">>...\n\n", [Text]);
+	    io:fwrite(standard_error, "  output:<<\"~s\">>...\n\n", [Text]);
 	_ ->
-	    io:fwrite("  output:<<\"~s\">>\n\n", [Output])
+	    io:fwrite(standard_error, "  output:<<\"~s\">>\n\n", [Output])
     end;
 print_test_error({skipped, Reason}, _) ->
-    io:fwrite("*did not run*\n::~s\n", [format_skipped(Reason)]).
+    io:fwrite(standard_error, "*did not run*\n::~s\n", [format_skipped(Reason)]).
 
 format_skipped({module_not_found, M}) ->
     io_lib:format("missing module: ~w", [M]);
@@ -231,13 +231,13 @@ format_skipped({no_such_function, {M,F,A}}) ->
     io_lib:format("no such function: ~w:~w/~w", [M,F,A]).    
 
 print_test_cancel(Reason) ->
-    io:fwrite(format_cancel(Reason)).
+    io:fwrite(standard_error, format_cancel(Reason)).
 
 print_group_cancel(_I, {blame, _}) ->
     ok;
 print_group_cancel(I, Reason) ->
     indent(I),
-    io:fwrite(format_cancel(Reason)).
+    io:fwrite(standard_error, format_cancel(Reason)).
 
 format_cancel(undefined) ->
     "*skipped*\n";
diff --git a/lib/hipe/cerl/cerl_cconv.erl b/lib/hipe/cerl/cerl_cconv.erl
index cf4d317b0de1..0c2814a886b6 100644
--- a/lib/hipe/cerl/cerl_cconv.erl
+++ b/lib/hipe/cerl/cerl_cconv.erl
@@ -552,7 +552,7 @@ fun_info(E, Env, S) ->
 	    %% io:fwrite("Got fun-info: ~w: {~w,~w}.\n", [Name,Id,H]),
 	    {#fun_info{name = Name, id = Id, hash = H}, S};
 	_ ->
-	    io:fwrite("Warning - fun not annotated: "
+	    io:fwrite(standard_error, "Warning - fun not annotated: "
 		      "making up new name.\n"), % for now
  	    {{Name,_Arity}, S1} = new_fun_name(E, Env, S),
  	    {#fun_info{name = Name, id = 0, hash = 0}, S1}
diff --git a/lib/hipe/icode/hipe_icode_type.erl b/lib/hipe/icode/hipe_icode_type.erl
index 3f9488d7c331..109b5cd99622 100644
--- a/lib/hipe/icode/hipe_icode_type.erl
+++ b/lib/hipe/icode/hipe_icode_type.erl
@@ -1266,7 +1266,8 @@ strength_reduce(I, Op) ->
           case hipe_icode:is_const(Arg2) of
             true ->
               case hipe_icode:const_value(Arg2) of
-		  0 -> io:fwrite("Integer division by 0 detected!\n"), I;
+		  0 -> io:fwrite(standard_error,
+			 "Integer division by 0 detected!\n"), I;
 		  1 -> case call_dstlist(I) of
 			 [] -> remove_useless_arithmetic_instruction(I);
 			 [Dst] -> create_strength_reduce_move(I, Dst, Arg1)
@@ -1293,7 +1294,8 @@ strength_reduce(I, Op) ->
 	  case hipe_icode:is_const(Arg2) of
 	    true ->
 	      case hipe_icode:const_value(Arg2) of
-		  0 -> io:fwrite("Remainder with 0 detected!\n"), I;
+		  0 -> io:fwrite(standard_error,
+			 "Remainder with 0 detected!\n"), I;
 		  1 -> case call_dstlist(I) of
 			 [] -> remove_useless_arithmetic_instruction(I);
 			 [Dst] -> create_strength_reduce_move(
diff --git a/lib/ic/src/ic.erl b/lib/ic/src/ic.erl
index 50fad921c4e6..7fcbc9b59833 100644
--- a/lib/ic/src/ic.erl
+++ b/lib/ic/src/ic.erl
@@ -81,19 +81,19 @@ gen(File, Opts) ->
     case catch gen2(G, File, Opts) of
 	{_, {'EXIT', R}} -> 
 	    ic_genobj:free_table_space(G), %% Free space for all ETS tables
-	    io:format("Fatal error : ~p~n",[R]),
+	    io:format(standard_error, "Fatal error : ~p~n",[R]),
 	    error;
 	{_, {'EXIT', _, R}} -> 
 	    ic_genobj:free_table_space(G), %% Free space for all ETS tables
-	    io:format("Fatal error : ~p~n",[R]),
+	    io:format(standard_error, "Fatal error : ~p~n",[R]),
 	    error;
 	{'EXIT', R} -> 
 	    ic_genobj:free_table_space(G), %% Free space for all ETS tables
-	    io:format("Fatal error : ~p~n",[R]),
+	    io:format(standard_error, "Fatal error : ~p~n",[R]),
 	    error;
 	{'EXIT', _, R} -> 
 	    ic_genobj:free_table_space(G), %% Free space for all ETS tables
-	    io:format("Fatal error : ~p~n",[R]),
+	    io:format(standard_error, "Fatal error : ~p~n",[R]),
 	    error;	
 	%% In this case, the pragma registration 
         %% found errors so this should return error.
@@ -335,7 +335,7 @@ typing(G, File, Clean) ->
 		       time("type code appliance  ", ic, do_type, [G,Clean]),
 		       ic:do_type(G,Clean)) of
 	{'EXIT',Reason} ->
-	    io:format("Error under type appliance : ~p~n",[Reason]),
+	    io:format(standard_error, "Error under type appliance : ~p~n",[Reason]),
 	    error;
        
 	T2 ->	    
diff --git a/lib/ic/src/ic_error.erl b/lib/ic/src/ic_error.erl
index f41e78a8be1a..d336bd33db89 100644
--- a/lib/ic/src/ic_error.erl
+++ b/lib/ic/src/ic_error.erl
@@ -307,11 +307,11 @@ format_warn({warn, _, File, {WarnString, Line}}) ->
 
 %% Display an error or warning
 display(File, not_specified, F, A) ->
-    io:format("~p : ~s~n", [File, io_lib:format(F, A)]);
+    io:format(standard_error, "~p : ~s~n", [File, io_lib:format(F, A)]);
 display(File, Line, F, A) ->
-    io:format("~p on line ~p: ~s~n", [File, Line, io_lib:format(F, A)]).
+    io:format(standard_error, "~p on line ~p: ~s~n", [File, Line, io_lib:format(F, A)]).
 display(File, F, A) ->
-    io:format("~p: ~s~n", [File, io_lib:format(F, A)]).
+    io:format(standard_error, "~p: ~s~n", [File, io_lib:format(F, A)]).
 
 
 
@@ -319,7 +319,7 @@ display(File, F, A) ->
 %%    case {ic_options:get_opt(G, silent), ic_options:get_opt(G, silent2), 
 %%          ic_options:get_opt(G, nowarn)} of
 %%	{false, false, false} ->
-%%	    io:format("~p: warning: ~s~n", [ic_genobj:idlfile(G), WarnStr]);
+%%	    io:format(standard_error, "~p: warning: ~s~n", [ic_genobj:idlfile(G), WarnStr]);
 %%	_ -> ok
 %%    end.
 
@@ -327,7 +327,7 @@ display(File, F, A) ->
 %%    case {ic_options:get_opt(G, silent), ic_options:get_opt(G, silent2),
 %%          ic_options:get_opt(G, nowarn)} of
 %%	{false, false, false} ->
-%%	    io:format("~p on line ~p: warning: ~s~n", 
+%%	    io:format(standard_error, "~p on line ~p: warning: ~s~n", 
 %%		      [ic_genobj:idlfile(G), Line, WarnStr]);
 %%	_ -> ok
 %%    end.
diff --git a/lib/ic/src/ic_jbe.erl b/lib/ic/src/ic_jbe.erl
index 81798d0429d4..f6feb8127da0 100644
--- a/lib/ic/src/ic_jbe.erl
+++ b/lib/ic/src/ic_jbe.erl
@@ -296,7 +296,8 @@ gen_member_2(G, N, X, [_T|Ts]) ->
 
 
 gen_exception(_G, N, X) ->
-    io:format("Warning : Exceptions not supported for java mapping, ~p ignored\n",
+    io:format(standard_error,
+	     "Warning : Exceptions not supported for java mapping, ~p ignored\n",
 	     [ic_util:to_colon([ic_forms:get_java_id(X)|N])]),
     ok.
 
diff --git a/lib/ic/src/ic_pp.erl b/lib/ic/src/ic_pp.erl
index 8b53473caac7..43eb605be7bb 100644
--- a/lib/ic/src/ic_pp.erl
+++ b/lib/ic/src/ic_pp.erl
@@ -648,11 +648,11 @@ expand(List, Defs, Err, War, [FileName|IncFile], IncDir, Mio) ->
 %% Main loop for the expansion
 %%=======================================================
 expand([], Out, _SelfRef, Defs, _IncFile, _IncDir, Mio, IfCou, Err, War, _L, _FN) ->
-%    io:format("~n   ===============~n"),
-%    io:format("   definitions    ~p~n",[lists:reverse(Defs)]),
-%    io:format("   found warnings ~p~n",[lists:reverse(War)]),
-%    io:format("   found errors   ~p~n",[lists:reverse(Err)]),
-%    io:format("   ===============~n~n~n"),
+%    io:format(standard_error, "~n   ===============~n"),
+%    io:format(standard_error, "   definitions    ~p~n",[lists:reverse(Defs)]),
+%    io:format(standard_error, "   found warnings ~p~n",[lists:reverse(War)]),
+%    io:format(standard_error, "   found errors   ~p~n",[lists:reverse(Err)]),
+%    io:format(standard_error, "   ===============~n~n~n"),
     {Out, Err, War, Defs, Mio, IfCou};
 
 expand([{file_info, Str} | Rem], Out, SelfRef, Defs, IncFile, IncDir, Mio, IfCou, Err, War, L, FN) ->
@@ -856,7 +856,7 @@ expand([{command,Command} | Rem], Out, SelfRef, Defs, IncFile, IncDir, Mio, chec
 	    end;
 
 	Else ->
-%	    io:format(" %%%%Else%%%%%% ~p~n",[Else]),
+%	    io:format(standard_error, " %%%%Else%%%%%% ~p~n",[Else]),
 	    exit(Else)
     end;
 
diff --git a/lib/ic/src/ic_pragma.erl b/lib/ic/src/ic_pragma.erl
index beaa2852ab9b..6b5ff2eb3d08 100644
--- a/lib/ic/src/ic_pragma.erl
+++ b/lib/ic/src/ic_pragma.erl
@@ -71,11 +71,11 @@ pragma_reg(G,X) ->
 	    %% Just print the number of errors found
 	    case ErrorNr > 1 of
 		true ->
-		    io:format("There were ~p errors found on file ~p~n",
+		    io:format(standard_error, "There were ~p errors found on file ~p~n",
 			      [ErrorNr,get_idlfile(S)]),
 		    error;
 		false ->
-		    io:format("There were ~p error found on file ~p~n",
+		    io:format(standard_error, "There were ~p error found on file ~p~n",
 			      [ErrorNr,get_idlfile(S)]),
 		    error
 	    end 
@@ -218,8 +218,8 @@ pragma_reg(G, S, N, X)  when element(1, X) == pragma ->
 		    pragma_reg_codeOpt(G,S,N,X);
 		
 		{pragma,{_,LineNr,BadPragma}, _To, _Apply} ->
-		    io:format("Warning : on file ~p :~n",[get_idlfile(S)]),
-		    io:format("  Unknown pragma directive ~p on line ~p, ignored.~n",
+		    io:format(standard_error, "Warning : on file ~p :~n",[get_idlfile(S)]),
+		    io:format(standard_error, "  Unknown pragma directive ~p on line ~p, ignored.~n",
 			      [BadPragma,LineNr])
 	    end;
 
@@ -346,17 +346,17 @@ pragma_reg_ID(G, S, N, X) ->
 		    insert(S,{id,X,LineNr,N,File,Type});
 		false ->
 		    set_compilation_failure(S),
-		    io:format("Error on file ~p :~n",[get_idlfile(S)]),
-		    io:format("  Bad pragma ID ~p on line ~p,~n",
+		    io:format(standard_error, "Error on file ~p :~n",[get_idlfile(S)]),
+		    io:format(standard_error, "  Bad pragma ID ~p on line ~p,~n",
 			      [element(3,Apply),LineNr]),
-		    io:format("  the version part of ID is not a short integer.~n")
+		    io:format(standard_error, "  the version part of ID is not a short integer.~n")
 	    end;
 	["LOCAL"|_] ->
 	    insert(S,{id,X,LineNr,N,File,Type});
 	_ ->
 	    set_compilation_failure(S),
-	    io:format("Error on file ~p :~n",[get_idlfile(S)]),
-	    io:format("  Bad pragma ID ~p on line ~p.~n",
+	    io:format(standard_error, "Error on file ~p :~n",[get_idlfile(S)]),
+	    io:format(standard_error, "  Bad pragma ID ~p on line ~p.~n",
 		      [element(3,Apply),LineNr])
     end.
 
@@ -380,17 +380,17 @@ pragma_reg_version(G, S, N, X) ->
 		    insert(S,{version,X,LineNr,N,File,Type});
 		false ->
 		    set_compilation_failure(S),
-		    io:format("Error on file ~p :~n",[get_idlfile(S)]),
-		    io:format("  Bad pragma version ~p on line ~p,~n",
+		    io:format(standard_error, "Error on file ~p :~n",[get_idlfile(S)]),
+		    io:format(standard_error, "  Bad pragma version ~p on line ~p,~n",
 			      [Apply,LineNr]),
-		    io:format("  the version is not valid.~n")
+		    io:format(standard_error, "  the version is not valid.~n")
 	    end;
 	_ ->
 	    set_compilation_failure(S),
-	    io:format("Error on file ~p :~n",[get_idlfile(S)]),
-	    io:format("  Bad pragma version ~p on line ~p,~n",
+	    io:format(standard_error, "Error on file ~p :~n",[get_idlfile(S)]),
+	    io:format(standard_error, "  Bad pragma version ~p on line ~p,~n",
 		      [Apply,LineNr]),
-	    io:format("  the version is not valid.~n")
+	    io:format(standard_error, "  the version is not valid.~n")
     end.
 
 
@@ -466,8 +466,8 @@ applyCodeOpts(G,S,LNr,[X|Xs]) ->
 	    applyCodeOpts(G,S,LNr,Xs);
 	false ->
 	    %% Print warning and continue
-	    io:format("Warning on file ~p :~n",[get_idlfile(S)]),
-	    io:format("  Bad option in pragma : ~p, ignored !~n",[X]),
+	    io:format(standard_error, "Warning on file ~p :~n",[get_idlfile(S)]),
+	    io:format(standard_error, "  Bad option in pragma : ~p, ignored !~n",[X]),
 	    applyCodeOpts(G,S,LNr,Xs)
     end.
 
diff --git a/lib/ic/src/icstruct.erl b/lib/ic/src/icstruct.erl
index 6058b3c45547..f62a3069801c 100644
--- a/lib/ic/src/icstruct.erl
+++ b/lib/ic/src/icstruct.erl
@@ -62,7 +62,8 @@ except_gen(G, N, X, L) when is_record(X, except) ->
     N2 = [ic_forms:get_id2(X) | N],
     if
 	L == c ->
-	    io:format("Warning : Exception not defined for c mapping\n", []);
+	    io:format(standard_error,
+		    "Warning : Exception not defined for c mapping\n", []);
 	true ->
 	    emit_struct(G, N, X, L)
     end,
diff --git a/lib/ic/src/ictype.erl b/lib/ic/src/ictype.erl
index 9e20801464c3..0b77bf9432b8 100644
--- a/lib/ic/src/ictype.erl
+++ b/lib/ic/src/ictype.erl
@@ -1065,7 +1065,7 @@ calc_inherit_body(G, N, OrigBody, [X|Xs], InhBody) ->
 	    Body = filter_body(G, X, ic_forms:get_body(Intf), N, OrigBody, InhBody),
 	    calc_inherit_body(G, N, OrigBody, Xs, [{X, Body} | InhBody]);
 	XXX ->
-	    io:format("Oops, not found ~p~n", [XXX]),
+	    io:format(standard_error, "Oops, not found ~p~n", [XXX]),
 	    calc_inherit_body(G, N, OrigBody, Xs, InhBody)
     end;
 calc_inherit_body(_G, _N, _OrigBody, [], InhBody) -> lists:reverse(InhBody).
diff --git a/lib/parsetools/src/leex.erl b/lib/parsetools/src/leex.erl
index cdf20461d993..bed51202ca2e 100644
--- a/lib/parsetools/src/leex.erl
+++ b/lib/parsetools/src/leex.erl
@@ -298,10 +298,10 @@ pack_warnings([]) ->
 report_errors(St) ->
     when_opt(fun () -> 
                      foreach(fun({File,{none,Mod,E}}) -> 
-                                     io:fwrite("~s: ~s\n",
+                                     io:fwrite(standard_error, "~s: ~s\n",
                                                [File,Mod:format_error(E)]);
                                 ({File,{Line,Mod,E}}) -> 
-                                     io:fwrite("~s:~w: ~s\n",
+                                     io:fwrite(standard_error, "~s:~w: ~s\n",
                                                [File,Line,Mod:format_error(E)])
                              end, sort(St#leex.errors))
              end, report_errors, St#leex.opts).
@@ -316,11 +316,11 @@ report_warnings(St) ->
     ShouldReport = member(report_warnings, St#leex.opts) orelse ReportWerror,
     when_bool(fun () ->
 		      foreach(fun({File,{none,Mod,W}}) ->
-				      io:fwrite("~s: ~s~s\n",
+				      io:fwrite(standard_error, "~s: ~s~s\n",
 						[File,Prefix,
 						 Mod:format_error(W)]);
 				 ({File,{Line,Mod,W}}) ->
-				      io:fwrite("~s:~w: ~s~s\n",
+				      io:fwrite(standard_error, "~s:~w: ~s~s\n",
 						[File,Line,Prefix,
 						 Mod:format_error(W)])
 			      end, sort(St#leex.warnings))
diff --git a/lib/parsetools/src/yecc.erl b/lib/parsetools/src/yecc.erl
index b0792a6ed808..00afa934d0c4 100644
--- a/lib/parsetools/src/yecc.erl
+++ b/lib/parsetools/src/yecc.erl
@@ -841,10 +841,10 @@ report_errors(St) ->
     case member(report_errors, St#yecc.options) of
         true ->
             foreach(fun({File,{none,Mod,E}}) -> 
-                            io:fwrite(<<"~s: ~s\n">>, 
+                            io:fwrite(standard_error, <<"~s: ~s\n">>, 
                                       [File,Mod:format_error(E)]);
                        ({File,{Line,Mod,E}}) -> 
-                            io:fwrite(<<"~s:~w: ~s\n">>, 
+                            io:fwrite(standard_error, <<"~s:~w: ~s\n">>, 
                                       [File,Line,Mod:format_error(E)])
                     end, sort(St#yecc.errors));
         false -> 
@@ -861,11 +861,11 @@ report_warnings(St) ->
     case member(report_warnings, St#yecc.options) orelse ReportWerror of
         true ->
             foreach(fun({File,{none,Mod,W}}) -> 
-                            io:fwrite(<<"~s: ~s~s\n">>,
+                            io:fwrite(standard_error, <<"~s: ~s~s\n">>,
                                       [File,Prefix,
 				       Mod:format_error(W)]);
                        ({File,{Line,Mod,W}}) -> 
-                            io:fwrite(<<"~s:~w: ~s~s\n">>,
+                            io:fwrite(standard_error, <<"~s:~w: ~s~s\n">>,
                                       [File,Line,Prefix,
 				       Mod:format_error(W)])
                     end, sort(St#yecc.warnings));
@@ -1549,12 +1549,13 @@ find_action_conflicts(St0) ->
               end, {Cxt0, []}, St0#yecc.parse_actions),
     if 
         length(Res) > 0, St#yecc.verbose -> 
-            io:fwrite(<<"\n*** Conflicts resolved by operator "
+            io:fwrite(standard_error,
+                      <<"\n*** Conflicts resolved by operator "
                         "precedences:\n\n">>),
             foreach(fun({Confl, Name}) ->
                             report_conflict(Confl, St, Name, prec)
                     end, reverse(Res)),
-            io:fwrite(<<"*** End of resolved conflicts\n\n">>);
+            io:fwrite(standard_error, <<"*** End of resolved conflicts\n\n">>);
         true -> 
             ok
     end,
diff --git a/lib/parsetools/src/yeccscan.erl b/lib/parsetools/src/yeccscan.erl
index d7ec3ba8d355..79dee6b34d94 100644
--- a/lib/parsetools/src/yeccscan.erl
+++ b/lib/parsetools/src/yeccscan.erl
@@ -37,7 +37,8 @@ scan(Inport, Prompt, Line1) ->
 	{error, Descriptor, Line2} ->
 	    {error, Descriptor, Line2};
 	{'EXIT', Why} ->
-	    io:format('yeccscan: Error scanning input line ~w~n', [Line1]),
+	    io:format(standard_error,
+		    'yeccscan: Error scanning input line ~w~n', [Line1]),
 	    exit(Why)
     end.
 
diff --git a/lib/reltool/src/reltool.erl b/lib/reltool/src/reltool.erl
index 54eb1ca9e164..c531cb75304f 100644
--- a/lib/reltool/src/reltool.erl
+++ b/lib/reltool/src/reltool.erl
@@ -120,7 +120,8 @@ apply_fun(Pid, false, Fun) ->
 apply_fun(Pid, true, Fun) ->
     case get_status(Pid) of
 	{ok, Warnings} ->
-	    [io:format("~p: ~s\n", [?APPLICATION, W]) || W <- Warnings],
+	    [io:format(standard_error, "~p: ~s\n", [?APPLICATION, W])
+		    || W <- Warnings],
 	    apply_fun(Pid, false, Fun);
 	{error, _Reason} = Error ->
 	    stop(Pid),
diff --git a/lib/reltool/src/reltool_sys_win.erl b/lib/reltool/src/reltool_sys_win.erl
index 8b0f64eb4529..084db316c5c0 100644
--- a/lib/reltool/src/reltool_sys_win.erl
+++ b/lib/reltool/src/reltool_sys_win.erl
@@ -175,12 +175,13 @@ do_init([{safe_config, Safe}, {parent, Parent} | Options]) ->
 		    restart_server_safe_config(Safe,Parent,Reason)
 	    end;
 	{error, Reason} ->
-	    io:format("~p(~p): <ERROR> ~p\n", [?MODULE, ?LINE, Reason]),
+	    io:format(standard_error, "~p(~p): <ERROR> ~p\n",
+		    [?MODULE, ?LINE, Reason]),
 	    exit(Reason)
     end.
 
 restart_server_safe_config(true,_Parent,Reason) ->
-    io:format("~p(~p): <ERROR> ~p\n", [?MODULE, ?LINE, Reason]),
+    io:format(standard_error, "~p(~p): <ERROR> ~p\n", [?MODULE, ?LINE, Reason]),
     exit(Reason);
 restart_server_safe_config(false,Parent,Reason) ->
     Strings =
@@ -196,7 +197,8 @@ restart_server_safe_config(false,Parent,Reason) ->
 	?wxID_OK ->
 	    do_init([{safe_config,true},{parent,Parent},?safe_config]);
 	?wxID_CANCEL ->
-	    io:format("~p(~p): <ERROR> ~p\n", [?MODULE, ?LINE, Reason]),
+	    io:format(standard_error, "~p(~p): <ERROR> ~p\n",
+		    [?MODULE, ?LINE, Reason]),
 	    exit(Reason)
     end.
 
@@ -209,7 +211,8 @@ exit_dialog(Warnings) ->
         ?wxID_OK ->
 	    ok;
         ?wxID_CANCEL  ->
-	    io:format("~p(~p): <ERROR> ~s\n", [?MODULE, ?LINE, Details]),
+	    io:format(standard_error, "~p(~p): <ERROR> ~s\n",
+		    [?MODULE, ?LINE, Details]),
 	    exit(Details)
     end.
 
diff --git a/lib/sasl/src/systools.erl b/lib/sasl/src/systools.erl
index 51ef687047d0..e3fe8561e3c5 100644
--- a/lib/sasl/src/systools.erl
+++ b/lib/sasl/src/systools.erl
@@ -72,7 +72,7 @@ make_tar(RelName, Opt) ->
 script2boot(File) ->
     case systools_lib:file_term2binary(File ++ ".script", File ++ ".boot") of
 	{error,Error} ->
-	    io:format(systools_make:format_error(Error)),
+	    io:format(standard_error, systools_make:format_error(Error)),
 	    error;
 	_ ->
 	    ok
@@ -83,7 +83,7 @@ script2boot(File, Output0, _Opt) ->
     Output = Output0++".boot",
     case systools_lib:file_term2binary(Input, Output) of
 	{error,Error} ->
-	    io:format(systools_make:format_error(Error)),
+	    io:format(standard_error, systools_make:format_error(Error)),
 	    error;
 	_ ->
 	    ok
diff --git a/lib/sasl/src/systools_make.erl b/lib/sasl/src/systools_make.erl
index 12ba2a5476f6..6e3beeee374c 100644
--- a/lib/sasl/src/systools_make.erl
+++ b/lib/sasl/src/systools_make.erl
@@ -156,10 +156,10 @@ return(ok,Warnings,Flags) ->
 	_ ->
 	    case member(warnings_as_errors,Flags) of
 		true ->
-		    io:format("~s",[format_warning(Warnings, true)]),
+		    io:format(standard_error,"~s",[format_warning(Warnings, true)]),
 		    error;
 		false ->
-		    io:format("~s",[format_warning(Warnings)]),
+		    io:format(standard_error,"~s",[format_warning(Warnings)]),
 		    ok
 	    end
     end;
@@ -168,7 +168,7 @@ return({error,Mod,Error},_,Flags) ->
 	true ->
 	    {error,Mod,Error};
 	_ ->
-	    io:format("~s",[Mod:format_error(Error)]),
+	    io:format(standard_error,"~s",[Mod:format_error(Error)]),
 	    error
     end.
 
@@ -903,7 +903,7 @@ check_modules(Appls, Path, TestP, Machine) ->
 		    Return
 	    end;
 	Dups ->
-%	    io:format("** ERROR Duplicate modules: ~p\n", [Dups]),
+%	    io:format(standard_error, "** ERROR Duplicate modules: ~p\n", [Dups]),
 	    throw({error, {duplicate_modules, Dups}})
     end.
 
diff --git a/lib/sasl/src/systools_relup.erl b/lib/sasl/src/systools_relup.erl
index 7fb623bb853f..b129f91f34b7 100644
--- a/lib/sasl/src/systools_relup.erl
+++ b/lib/sasl/src/systools_relup.erl
@@ -595,9 +595,9 @@ print_error({'EXIT', Err}) ->
     print_error(Err);
 print_error({error, Mod, Error}) ->
     S = apply(Mod, format_error, [Error]),
-    io:format(S, []);
+    io:format(standard_error, S, []);
 print_error(Other) ->
-    io:format("Error: ~p~n", [Other]).
+    io:format(standard_error, "Error: ~p~n", [Other]).
 
 format_error({file_problem, {"relup", _Posix}}) ->
     io_lib:format("Could not open file relup~n", []);
@@ -612,7 +612,7 @@ format_error({missing_sasl,Release}) ->
     io_lib:format("No sasl application in release ~p, ~p. Can not be upgraded.",
 		  [Release#release.name, Release#release.vsn]);
 format_error(Error) ->
-    io:format("~p~n", [Error]).
+    io:format(standard_error, "~p~n", [Error]).
 
 
 print_warnings(Ws, Opts) when is_list(Ws) ->
@@ -628,7 +628,7 @@ print_warning(W, Opts) ->
 		     "*WARNING* "
 	     end,
     S = format_warning(Prefix, W),
-    io:format("~s", [S]).
+    io:format(standard_error, "~s", [S]).
 
 format_warning(W) ->
     format_warning("*WARNING* ", W).
diff --git a/lib/snmp/src/agent/snmpa_error_io.erl b/lib/snmp/src/agent/snmpa_error_io.erl
index 54cdb6baac69..91ae752ec1de 100644
--- a/lib/snmp/src/agent/snmpa_error_io.erl
+++ b/lib/snmp/src/agent/snmpa_error_io.erl
@@ -45,5 +45,5 @@ config_err(F, A) ->
 
 
 error_msg(P, F, A) ->
-    io:format("*** SNMP ~s *** ~n" ++ F ++ "~n", [P|A]).
+    io:format(standard_error, "*** SNMP ~s *** ~n" ++ F ++ "~n", [P|A]).
 
diff --git a/lib/snmp/src/compile/snmpc.erl b/lib/snmp/src/compile/snmpc.erl
index 5e6b81f1ecf9..01d908dbc180 100644
--- a/lib/snmp/src/compile/snmpc.erl
+++ b/lib/snmp/src/compile/snmpc.erl
@@ -63,7 +63,7 @@ compile(Input, _Output, Options) ->
         {ok, _} ->
             ok;
         {error, Reason} ->
-            io:format("~p", [Reason]),
+            io:format(standard_error, "~p", [Reason]),
             error
     end.
 
diff --git a/lib/snmp/src/compile/snmpc_lib.erl b/lib/snmp/src/compile/snmpc_lib.erl
index 38bb8f3ac661..14351d6593cd 100644
--- a/lib/snmp/src/compile/snmpc_lib.erl
+++ b/lib/snmp/src/compile/snmpc_lib.erl
@@ -482,8 +482,8 @@ is_consistent(Filenames) ->
 	ok -> 
 	    ok;
 	{undef, Format, Data} ->
-	    ok = io:format(Format, Data),
-	    io:format("~n"),
+	    ok = io:format(standard_error, Format, Data),
+	    io:format(standard_error, "~n"),
 	    {error, inconsistent}
     end.
     
@@ -1754,14 +1754,15 @@ error(FormatStr, Data, Line) when is_list(FormatStr) ->
     exit(error).
 
 print_error(FormatStr, Data) when is_list(FormatStr) ->
-    ok = io:format("~s: " ++ FormatStr,[get(filename)|Data]),
+    ok = io:format(standard_error, "~s: " ++ FormatStr,[get(filename)|Data]),
     put(errors,yes),
-    io:format("~n").
+    io:format(standard_error, "~n").
     
 print_error(FormatStr, Data,Line) when is_list(FormatStr) ->
-    ok = io:format("~s: ~w: " ++ FormatStr,[get(filename), Line |Data]),
+    ok = io:format(standard_error, "~s: ~w: " ++ FormatStr,
+                   [get(filename), Line |Data]),
     put(errors,yes),
-    io:format("~n").
+    io:format(standard_error, "~n").
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/lib/snmp/src/compile/snmpc_mib_to_hrl.erl b/lib/snmp/src/compile/snmpc_mib_to_hrl.erl
index e8c46a052140..6f3442916ece 100644
--- a/lib/snmp/src/compile/snmpc_mib_to_hrl.erl
+++ b/lib/snmp/src/compile/snmpc_mib_to_hrl.erl
@@ -337,7 +337,7 @@ compile(Input, Output, Opts) ->
 	ok ->
 	    ok;
 	{error, Reason} ->
-	    io:format("~p", [Reason]),
+	    io:format(standard_error, "~p", [Reason]),
 	    error
     end.
 
diff --git a/lib/stdlib/src/c.erl b/lib/stdlib/src/c.erl
index a920921a5ede..f63a63bc4138 100644
--- a/lib/stdlib/src/c.erl
+++ b/lib/stdlib/src/c.erl
@@ -35,7 +35,7 @@
 
 -import(lists, [reverse/1,flatten/1,sublist/3,sort/1,keysort/2,
 		concat/1,max/1,min/1,foreach/2,foldl/3,flatmap/2]).
--import(io, [format/1, format/2]).
+-import(io, [format/1, format/2, format/3]).
 
 %%-----------------------------------------------------------------------
 
@@ -122,12 +122,14 @@ machine_load(Mod, File, Opts) ->
 		    code:purge(Mod),
 		    check_load(code:load_abs(File2,Mod), Mod);
 		_OtherMod ->
-		    format("** Module name '~p' does not match file name '~p' **~n",
+		    format(standard_error,
+			   "** Module name '~p' does not match file name '~p' **~n",
 			   [Mod,File]),
 		    {error, badfile}
 	    end;
 	false ->
-	    format("** Warning: No object file created - nothing loaded **~n", []),
+	    format(standard_error,
+			   "** Warning: No object file created - nothing loaded **~n", []),
 	    ok
     end.
 
@@ -162,7 +164,7 @@ lc(Args) ->
 -spec lc_batch() -> no_return().
 
 lc_batch() ->
-    io:format("Error: no files to compile~n"),
+    io:format(standard_error, "Error: no files to compile~n"),
     halt(1).
 
 -spec lc_batch([erl_compile:cmd_line_arg()]) -> no_return().
@@ -203,11 +205,11 @@ make_term(Str) ->
 	    case erl_parse:parse_term(Tokens ++ [{dot, 1}]) of
 		{ok, Term} -> Term;
 		{error, {_,_,Reason}} ->
-		    io:format("~s: ~s~n", [Reason, Str]),
+		    io:format(standard_error, "~s: ~s~n", [Reason, Str]),
 		    throw(error)
 	    end;
 	{error, {_,_,Reason}, _} ->
-	    io:format("~s: ~s~n", [Reason, Str]),
+	    io:format(standard_error, "~s: ~s~n", [Reason, Str]),
 	    throw(error)
     end.
 
@@ -682,7 +684,7 @@ pwd() ->
 	{ok, Str} ->
 	    ok = io:format("~ts\n", [fixup_one_bin(Str)]);
 	{error, _} ->
-	    ok = io:format("Cannot determine current directory\n")
+	    ok = io:format(standard_error, "Cannot determine current directory\n")
     end.
 
 -spec cd(Dir) -> 'ok' when
@@ -709,7 +711,7 @@ ls(Dir) ->
 	{ok, Entries} ->
 	    ls_print(sort(fixup_bin(Entries)));
 	{error,_E} ->
-	    format("Invalid directory\n")
+	    format(standard_error, "Invalid directory\n")
     end.
 
 fixup_one_bin(X) when is_binary(X) ->
@@ -799,7 +801,8 @@ appcall(App, M, F, Args) ->
 	    case erlang:get_stacktrace() of
 		[{M,F,Args,_}|_] ->
 		    Arity = length(Args),
-		    io:format("Call to ~w:~w/~w in application ~w failed.\n",
+		    io:format(standard_error,
+			      "Call to ~w:~w/~w in application ~w failed.\n",
 			      [M,F,Arity,App]);
 		Stk ->
 		    erlang:raise(error, undef, Stk)
diff --git a/lib/stdlib/src/epp.erl b/lib/stdlib/src/epp.erl
index ccc14610d74d..08303fed7b3b 100644
--- a/lib/stdlib/src/epp.erl
+++ b/lib/stdlib/src/epp.erl
@@ -345,7 +345,7 @@ wait_request(St) ->
 	{'EXIT',_,R} ->
 	    exit(R);
 	Other ->
-	    io:fwrite("Epp: unknown '~w'\n", [Other]),
+	    io:fwrite(standard_error, "Epp: unknown '~w'\n", [Other]),
 	    wait_request(St)
     end.
 
diff --git a/lib/stdlib/src/erl_compile.erl b/lib/stdlib/src/erl_compile.erl
index ff032b129c1b..724cf304cd6e 100644
--- a/lib/stdlib/src/erl_compile.erl
+++ b/lib/stdlib/src/erl_compile.erl
@@ -78,7 +78,7 @@ compile(List) ->
 	{'EXIT', Pid, {compiler_result, Result}} ->
 	    Result;
 	{'EXIT', Pid, Reason} ->
-	    io:format("Runtime error: ~p~n", [Reason]),
+	    io:format(standard_error, "Runtime error: ~p~n", [Reason]),
 	    error
     end.
 
@@ -152,7 +152,8 @@ compile2(Files, Cwd, Opts) ->
 	{[_|_], 1} ->
 	    compile3(Files, Cwd, Opts);
 	{[_|_], _N} ->
-	    io:format("Output file name given, but more than one input file.~n"),
+	    io:format(standard_error,
+	              "Output file name given, but more than one input file.~n"),
 	    error
     end.
 
@@ -180,24 +181,24 @@ compile3([], _Cwd, _Options) -> ok.
 %% Invokes the appropriate compiler, depending on the file extension.
 
 compile_file("", Input, _Output, _Options) ->
-    io:format("File has no extension: ~s~n", [Input]),
+    io:format(standard_error, "File has no extension: ~s~n", [Input]),
     error;
 compile_file(Ext, Input, Output, Options) ->
     case compiler(Ext) of
 	no ->
-	    io:format("Unknown extension: '~s'\n", [Ext]),
+	    io:format(standard_error, "Unknown extension: '~s'\n", [Ext]),
 	    error;
 	{M, F} ->
 	    case catch M:F(Input, Output, Options) of
 		ok -> ok;
 		error -> error;
 		{'EXIT',Reason} ->
-		    io:format("Compiler function ~w:~w/3 failed:\n~p~n",
+		    io:format(standard_error, "Compiler function ~w:~w/3 failed:\n~p~n",
 			      [M,F,Reason]),
 		    error;
 		Other ->
-		    io:format("Compiler function ~w:~w/3 returned:\n~p~n",
-			      [M,F,Other]),
+		    io:format(standard_error,
+		              "Compiler function ~w:~w/3 returned:\n~p~n", [M,F,Other]),
 		    error
 	    end
     end.
@@ -225,10 +226,10 @@ make_term(Str) ->
 	    case erl_parse:parse_term(Tokens ++ [{dot, 1}]) of
 		{ok, Term} -> Term;
 		{error, {_,_,Reason}} ->
-		    io:format("~s: ~s~n", [Reason, Str]),
+		    io:format(standard_error, "~s: ~s~n", [Reason, Str]),
 		    throw(error)
 	    end;
 	{error, {_,_,Reason}, _} ->
-	    io:format("~s: ~s~n", [Reason, Str]),
+	    io:format(standard_error, "~s: ~s~n", [Reason, Str]),
 	    throw(error)
     end.
diff --git a/lib/stdlib/src/escript.erl b/lib/stdlib/src/escript.erl
index ad49d899089a..b3abf6fadcc1 100644
--- a/lib/stdlib/src/escript.erl
+++ b/lib/stdlib/src/escript.erl
@@ -276,16 +276,16 @@ start(EscriptOptions) ->
             [File|Args] ->
                 parse_and_run(File, Args, EscriptOptions);
             [] ->
-                io:format("escript: Missing filename\n", []),
+                io:format(standard_error, "escript: Missing filename\n", []),
                 my_halt(127)
         end
     catch
         throw:Str ->
-            io:format("escript: ~s\n", [Str]),
+            io:format(standard_error, "escript: ~s\n", [Str]),
             my_halt(127);
         _:Reason ->
-            io:format("escript: Internal error: ~p\n", [Reason]),
-            io:format("~p\n", [erlang:get_stacktrace()]),
+            io:format(standard_error, "escript: Internal error: ~p\n", [Reason]),
+            io:format(standard_error, "~p\n", [erlang:get_stacktrace()]),
             my_halt(127)
     end.
 
@@ -610,7 +610,7 @@ parse_source(S, File, Fd, StartLine, HeaderSz, CheckOnly) ->
             ok = file:close(Fd),
 	    check_source(S3, CheckOnly);
 	{error, Reason} ->
-	    io:format("escript: ~p\n", [Reason]),
+	    io:format(standard_error, "escript: ~p\n", [Reason]),
 	    fatal("Preprocessor error")
     end.
 
@@ -680,7 +680,7 @@ epp_parse_file2(Epp, S, Forms, Parsed) ->
                             epp_parse_file(Epp, S2, [Form | Forms]);
                         true ->
                             Args = lists:flatten(io_lib:format("illegal mode attribute: ~p", [NewMode])),
-                            io:format("~s:~w ~s\n", [S#state.file,Ln,Args]),
+                            io:format(standard_error, "~s:~w ~s\n", [S#state.file,Ln,Args]),
                             Error = {error,{Ln,erl_parse,Args}},
                             Nerrs= S#state.n_errors + 1,
                             epp_parse_file(Epp, S2#state{n_errors = Nerrs}, [Error | Forms])
@@ -696,7 +696,7 @@ epp_parse_file2(Epp, S, Forms, Parsed) ->
                     epp_parse_file(Epp, S, [Form | Forms])
             end;
         {error,{Ln,Mod,Args}} = Form ->
-            io:format("~s:~w: ~s\n",
+            io:format(standard_error, "~s:~w: ~s\n",
                       [S#state.file,Ln,Mod:format_error(Args)]),
             epp_parse_file(Epp, S#state{n_errors = S#state.n_errors + 1}, [Form | Forms]);
         {eof, _LastLine} = Eof ->
@@ -766,10 +766,10 @@ report_errors(Errors) ->
                   Errors).
 
 list_errors(F, [{Line,Mod,E}|Es]) ->
-    io:fwrite("~s:~w: ~s\n", [F,Line,Mod:format_error(E)]),
+    io:fwrite(standard_error, "~s:~w: ~s\n", [F,Line,Mod:format_error(E)]),
     list_errors(F, Es);
 list_errors(F, [{Mod,E}|Es]) ->
-    io:fwrite("~s: ~s\n", [F,Mod:format_error(E)]),
+    io:fwrite(standard_error, "~s: ~s\n", [F,Mod:format_error(E)]),
     list_errors(F, Es);
 list_errors(_F, []) -> ok.
 
@@ -778,7 +778,7 @@ report_warnings(Ws0) ->
                            ({F,Eds}) -> format_message(F, Eds) end,
                   Ws0),
     Ws = ordsets:from_list(Ws1),
-    lists:foreach(fun({_,Str}) -> io:put_chars(Str) end, Ws).
+    lists:foreach(fun({_,Str}) -> io:put_chars(standard_error, Str) end, Ws).
 
 format_message(F, [{Line,Mod,E}|Es]) ->
     M = {{F,Line},io_lib:format("~s:~w: Warning: ~s\n", [F,Line,Mod:format_error(E)])},
@@ -823,7 +823,7 @@ code_handler(Name, Args, Dict, File) ->
                     %% io:format("Calling:~p~n",[{Mod,Name,Args}]),
                     apply(Mod, Name, Args);
                 error ->
-                    io:format("Script does not export ~w/~w\n", [Name,Arity]),
+                    io:format(standard_error, "Script does not export ~w/~w\n", [Name,Arity]),
                     my_halt(127)
             end
     end.
diff --git a/lib/stdlib/src/shell.erl b/lib/stdlib/src/shell.erl
index dc450f0ee6c1..52120a201fc2 100644
--- a/lib/stdlib/src/shell.erl
+++ b/lib/stdlib/src/shell.erl
@@ -753,7 +753,8 @@ used_records(E) ->
     {expr, E}.
 
 fwrite_severity(Severity, S, As) ->
-    io:fwrite(<<"~s\n">>, [format_severity(Severity, S, As)]).
+    io:fwrite(output_stream(Severity), <<"~s\n">>,
+              [format_severity(Severity, S, As)]).
 
 format_severity(Severity, S, As) ->
     add_severity(Severity, io_lib:fwrite(S, As)).
@@ -765,6 +766,10 @@ severity_tag(fatal)   -> <<"*** ">>;
 severity_tag(serious) -> <<"** ">>;
 severity_tag(benign)  -> <<"* ">>.
 
+output_stream(fatal)   -> standard_error;
+output_stream(serious) -> standard_error;
+output_stream(benign)  -> standard_io.
+
 restrict_handlers(RShMod, Shell, RT) ->
     { fun(F,As,Binds) -> 
 	      local_allowed(F, As, RShMod, Binds, Shell, RT) 
diff --git a/lib/test_server/src/test_server.erl b/lib/test_server/src/test_server.erl
index 51754cb3b494..0ceead6d94cb 100644
--- a/lib/test_server/src/test_server.erl
+++ b/lib/test_server/src/test_server.erl
@@ -301,7 +301,8 @@ cover_compile({none,_Exclude,Include,Cross}) ->
     CompileMods = Include++Cross,
     case length(CompileMods) of
 	0 ->
-	    io:fwrite("WARNING: No modules to cover compile!\n\n",[]),
+	    io:fwrite(standard_error,
+		      "WARNING: No modules to cover compile!\n\n",[]),
 	    cover:start(),			% start cover server anyway
 	    {ok,[]};
 	N ->
@@ -315,13 +316,15 @@ cover_compile({App,all,Include,Cross}) ->
     CompileMods = Include++Cross,
     case length(CompileMods) of
 	0 ->
-	    io:fwrite("WARNING: No modules to cover compile!\n\n",[]),
+	    io:fwrite(standard_error,
+		      "WARNING: No modules to cover compile!\n\n",[]),
 	    cover:start(),			% start cover server anyway
 	    {ok,[]};
 	N ->
 	    io:fwrite("Cover compiling '~w' (~w files) - "
 		      "this may take some time... ",[App,N]),
-	    io:format("\nWARNING: All modules in \'~w\' are excluded\n"
+	    io:format(standard_error,
+		      "\nWARNING: All modules in \'~w\' are excluded\n"
 		      "Only cover compiling modules in include list "
 		      "and the modules\nin the cross cover file:\n"
 		      "~p\n", [App,CompileMods]),
@@ -334,14 +337,16 @@ cover_compile({App,Exclude,Include,Cross}) ->
 	{error,bad_name} ->
 	    case Include++Cross of
 		[] ->
-		    io:format("\nWARNING: Can't find lib_dir for \'~w\'\n"
+		    io:format(standard_error,
+			      "\nWARNING: Can't find lib_dir for \'~w\'\n"
 			      "Not cover compiling!\n\n",[App]),
 		    {error,application_not_found};
 		CompileMods ->
 		    io:fwrite("Cover compiling '~w' (~w files) - "
 			      "this may take some time... ",
 			      [App,length(CompileMods)]),
-		    io:format("\nWARNING: Can't find lib_dir for \'~w\'\n"
+		    io:format(standard_error,
+			      "\nWARNING: Can't find lib_dir for \'~w\'\n"
 			      "Only cover compiling modules in include list: "
 			      "~p\n", [App,Include]),
 		    do_cover_compile(CompileMods),
@@ -356,7 +361,8 @@ cover_compile({App,Exclude,Include,Cross}) ->
 	    CompileMods = AnalyseMods ++ Cross,
 	    case length(CompileMods) of
 		0 ->
-		    io:fwrite("WARNING: No modules to cover compile!\n\n",[]),
+		    io:fwrite(standard_error,
+			      "WARNING: No modules to cover compile!\n\n",[]),
 		    cover:start(),		% start cover server anyway
 		    {ok,[]};
 		N ->
@@ -388,8 +394,8 @@ do_cover_compile1([M|Rest]) ->
 		{ok,_} ->
 		    ok;
 		Error ->
-		    io:fwrite("\nWARNING: Could not cover compile ~w: ~p\n",
-			      [M,Error])
+		    io:fwrite(standard_error,
+			      "\nWARNING: Could not cover compile ~w: ~p\n", [M,Error])
 	    end,
 	    code:stick_mod(M),
 	    do_cover_compile1(Rest);
@@ -398,7 +404,8 @@ do_cover_compile1([M|Rest]) ->
 		{module,_} ->
 		    do_cover_compile1([M|Rest]);
 		Error ->
-		    io:fwrite("\nWARNING: Could not load ~w: ~p\n",[M,Error]),
+		    io:fwrite(standard_error,
+		        "\nWARNING: Could not load ~w: ~p\n",[M,Error]),
 		    do_cover_compile1(Rest)
 	    end;
 	{false,_} ->
@@ -406,8 +413,8 @@ do_cover_compile1([M|Rest]) ->
 		{ok,_} ->
 		    ok;
 		Error ->
-		    io:fwrite("\nWARNING: Could not cover compile ~w: ~p\n",
-			      [M,Error])
+		    io:fwrite(standard_error,    
+			      "\nWARNING: Could not cover compile ~w: ~p\n", [M,Error])
 	    end,
 	    do_cover_compile1(Rest)
     end;
@@ -477,8 +484,8 @@ cover_analyse(Analyse,Modules) ->
 		      {ok,{M,{Cov,NotCov}}} ->
 			  {M,{Cov,NotCov,DetailsFun(M)}};
 		      Err ->
-			  io:fwrite("WARNING: Analysis failed for ~w. Reason: ~p\n",
-				    [M,Err]),
+			  io:fwrite(standard_error,
+				    "WARNING: Analysis failed for ~w. Reason: ~p\n", [M,Err]),
 			  {M,Err}
 		  end
 	  end, Modules),
diff --git a/lib/test_server/src/test_server_ctrl.erl b/lib/test_server/src/test_server_ctrl.erl
index 3432b3bc8e7a..355e5172c611 100644
--- a/lib/test_server/src/test_server_ctrl.erl
+++ b/lib/test_server/src/test_server_ctrl.erl
@@ -339,7 +339,7 @@ parse_cmd_line(['SPEC',Spec|Cmds], SpecList, Names, Param, Trc, Cov, TCCB) ->
 	    parse_cmd_line(Cmds, TermList++SpecList, [Name|Names], Param,
 			   Trc, Cov, TCCB);
 	{error,Reason} ->
-	    io:format("Can't open ~s: ~p\n",
+	    io:format(standard_error, "Can't open ~s: ~p\n",
 		      [cast_to_list(Spec), file:format_error(Reason)]),
 	    parse_cmd_line(Cmds, SpecList, Names, Param, Trc, Cov, TCCB)
     end;
@@ -370,9 +370,9 @@ parse_cmd_line(['COVER',App,CF,Analyse|Cmds], SpecList, Names, Param, Trc, _Cov,
 parse_cmd_line(['TESTCASE_CALLBACK',Mod,Func|Cmds], SpecList, Names, Param, Trc, Cov, _) ->
     parse_cmd_line(Cmds, SpecList, Names, Param, Trc, Cov, {Mod,Func});
 parse_cmd_line([Obj|_Cmds], _SpecList, _Names, _Param, _Trc, _Cov, _TCCB) ->
-    io:format("~p: Bad argument: ~p\n", [?MODULE,Obj]),
-    io:format(" Use the `ts' module to start tests.\n", []),
-    io:format(" (If you ARE using `ts', there is a bug in `ts'.)\n", []),
+    io:format(standard_error, "~p: Bad argument: ~p\n", [?MODULE,Obj]),
+    io:format(standard_error, " Use the `ts' module to start tests.\n", []),
+    io:format(standard_error, " (If you ARE using `ts', there is a bug in `ts'.)\n", []),
     halt(1);
 parse_cmd_line([], SpecList, Names, Param, Trc, Cov, TCCB) ->
     NameList = lists:reverse(Names, [suite]),
@@ -1207,9 +1207,9 @@ handle_info({'EXIT',Pid,Reason}, State) ->
 		normal ->
 		    fine;
 		killed ->
-		    io:format("Suite ~s was killed\n", [Name]);
+		    io:format(standard_error, "Suite ~s was killed\n", [Name]);
 		_Other ->
-		    io:format("Suite ~s was killed with reason ~p\n",
+		    io:format(standard_error, "Suite ~s was killed with reason ~p\n",
 			      [Name,Reason])
 	    end,
 	    State2 = State#state{jobs=NewJobs},
@@ -1253,7 +1253,8 @@ handle_info({tcp,_MainSock,<<1,Request/binary>>}, State) ->
 	    %% The local job proc will soon be killed by the closed socket or
 	    %% because the job is finished. Then the above clause ('EXIT') will
 	    %% handle the problem.
-	    io:format("Suite ~s was killed on remote target with reason"
+	    io:format(standard_error,
+		      "Suite ~s was killed on remote target with reason"
 		      " ~p\n", [Name,Reason]);
 	_ ->
 	    ignore
@@ -1454,7 +1455,7 @@ do_spec(SpecName, TimetrapSpec) when is_list(SpecName) ->
 	{ok,TermList} ->
 	    do_spec_list(TermList,TimetrapSpec);
 	{error,Reason} ->
-	    io:format("Can't open ~s: ~p\n", [SpecName,Reason]),
+	    io:format(standard_error, "Can't open ~s: ~p\n", [SpecName,Reason]),
 	    {error,{cant_open_spec,Reason}}
     end.
 
@@ -1537,7 +1538,7 @@ do_spec_terms([{require_nodenames,NumNames}|Terms], TopCases, SkipList, Config)
     do_spec_terms(Terms, TopCases, SkipList,
 		  update_config(Config, {nodenames,NodeNames}));
 do_spec_terms([Other|Terms], TopCases, SkipList, Config) ->
-    io:format("** WARNING: Spec file contains unknown directive ~p\n",
+    io:format(standard_error, "** WARNING: Spec file contains unknown directive ~p\n",
 	      [Other]),
     do_spec_terms(Terms, TopCases, SkipList, Config).
 
@@ -2087,7 +2088,7 @@ copy_html_file(Src, DestDir) ->
 	{ok,Bin} ->
 	    ok = file:write_file(Dest, Bin);
 	{error,_Reason} ->
-	    io:format("File ~p: read failed\n", [Src])
+	    io:format(standard_error, "File ~p: read failed\n", [Src])
     end.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -3842,7 +3843,7 @@ maybe_send_beam_and_datadir(Mod) ->
 send_beam_and_datadir(Mod, JobSock) ->
     case code:which(Mod) of
 	non_existing ->
-	    io:format("** WARNING: Suite ~w could not be found on host\n",
+	    io:format(standard_error, "** WARNING: Suite ~w could not be found on host\n",
 		      [Mod]);
 	BeamFile ->
 	    send_beam(JobSock, Mod, BeamFile)
@@ -4863,7 +4864,7 @@ collect_files(Dir, Pattern, St) ->
     Wc = filename:join([Dir1,Pattern++code:objfile_extension()]),
     case catch filelib:wildcard(Wc) of
 	{'EXIT', Reason} ->
-	    io:format("Could not collect files: ~p~n", [Reason]),
+	    io:format(standard_error, "Could not collect files: ~p~n", [Reason]),
 	    {error,{collect_fail,Dir,Pattern}};
 	Mods0 ->
 	    Mods = [{path_to_module(Mod),all} || Mod <- lists:sort(Mods0)],
@@ -5547,7 +5548,8 @@ write_coverlog_header(CoverLog) ->
 		  "link=\"blue\" vlink=\"purple\" alink=\"red\">",
 		  [?MODULE]) of
 	{'EXIT',Reason} ->
-	    io:format("\n\nERROR: Could not write normal heading in coverlog.\n"
+	    io:format(standard_error,
+		      "\n\nERROR: Could not write normal heading in coverlog.\n"
 		      "CoverLog: ~w\n"
 		      "Reason: ~p\n",
 		      [CoverLog,Reason]),
diff --git a/lib/test_server/src/ts_reports.erl b/lib/test_server/src/ts_reports.erl
index f981a77ae4fa..fc9ed23caf94 100644
--- a/lib/test_server/src/ts_reports.erl
+++ b/lib/test_server/src/ts_reports.erl
@@ -47,7 +47,8 @@ make_master_index1([Dir|Rest], Result) ->
     NewResult = 
 	case catch read_variables(Dir) of
 	    {'EXIT',{{bad_installation,Reason},_}} ->
-		io:put_chars("Failed to read " ++ filename:join(Dir,?variables)++
+		io:put_chars(standard_error,
+			     "Failed to read " ++ filename:join(Dir,?variables)++
 			     ": " ++ Reason ++ " - Ignoring this directory\n"),
 		Result;
 	    Vars ->
@@ -154,18 +155,19 @@ make_index(Dir, Vars, IncludeLast) ->
     io:put_chars("Updating " ++ IndexName ++ "... "),
     case catch make_index1(Dir, IndexName, Vars, IncludeLast) of
 	{'EXIT', Reason} ->
-	    io:put_chars("CRASHED!\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error, "CRASHED!\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	{error, Reason} ->
-	    io:put_chars("FAILED\n"),
-	    io:format("~p~n", [Reason]),
+	    io:put_chars(standard_error, "FAILED\n"),
+	    io:format(standard_error, "~p~n", [Reason]),
 	    {error, Reason};
 	{ok, Summary} ->
 	    io:put_chars("done\n"),
 	    {ok, Summary};
 	Err ->
-	    io:format("Unknown internal error. Please report.\n(Err: ~p, ID: 1)",
+	    io:format(standard_error,
+		      "Unknown internal error. Please report.\n(Err: ~p, ID: 1)",
 		      [Err]),
 	    {error, Err}
     end.
diff --git a/lib/test_server/src/ts_run.erl b/lib/test_server/src/ts_run.erl
index 885a3c9b96be..10672c882d5a 100644
--- a/lib/test_server/src/ts_run.erl
+++ b/lib/test_server/src/ts_run.erl
@@ -269,7 +269,7 @@ tricky_print_data(Port) ->
 		{ok,Names} ->
 		    case is_testnode_dead(Names) of
 			true ->
-			    io:put_chars("WARNING: No EOF, but "
+			    io:put_chars(standard_error, "WARNING: No EOF, but "
 					 "test_server node is down!\n");
 			false ->
 			    tricky_print_data(Port)
@@ -311,12 +311,12 @@ run_interactive(Vars, _Spec, State) ->
 start_xterm(Command) ->
     case os:find_executable("xterm") of
 	false ->
-	    io:format("The `xterm' program was not found.\n"),
+	    io:format(standard_error, "The `xterm' program was not found.\n"),
 	    {error, no_xterm};
 	_Xterm ->
 	    case os:getenv("DISPLAY") of
 		false ->
-		    io:format("DISPLAY is not set.\n"),
+		    io:format(standard_error, "DISPLAY is not set.\n"),
 		    {error, display_not_set};
 		Display ->
 		    io:format("Starting xterm (DISPLAY=~s)...\n",
@@ -350,7 +350,7 @@ make_common_test_args(Args0, Options, _Vars) ->
     Cover = 
 	case lists:keysearch(cover,1,Options) of
 	    {value,{cover, App, none, _Analyse}} ->
-		io:format("No cover file found for ~p~n",[App]),
+		io:format(standard_error, "No cover file found for ~p~n",[App]),
 		[];
 	    {value,{cover,_App,File,_Analyse}} -> 
 		[{cover,to_list(File)}];
diff --git a/lib/tools/src/cover.erl b/lib/tools/src/cover.erl
index e21bd1b88cc3..c2bbc3f53fb7 100644
--- a/lib/tools/src/cover.erl
+++ b/lib/tools/src/cover.erl
@@ -585,7 +585,7 @@ main_process_loop(State) ->
 				  link(RPid),
 				  [Node|Acc];
 			      Error ->
-				  io:format("Could not start cover on ~w: ~p\n",
+				  io:format(standard_error, "Could not start cover on ~w: ~p\n",
 					    [Node,Error]),
 				  Acc
 			  end
@@ -857,7 +857,7 @@ remote_process_loop(State) ->
 	    remote_process_loop(State);
 
 	M ->
-	    io:format("WARNING: remote cover_server received\n~p\n",[M]),
+	    io:format(standard_error, "WARNING: remote cover_server received\n~p\n",[M]),
 	    case M of
 		{From,_} ->
 		    case is_from(From) of
@@ -1148,7 +1148,8 @@ add_imported(Module, File, ImportFile, Imported) ->
 add_imported(M, F1, ImportFile, [{M,_F2,ImportFiles}|Imported], Acc) ->
     case lists:member(ImportFile,ImportFiles) of
 	true ->
-	    io:fwrite("WARNING: Module ~w already imported from ~p~n"
+	    io:fwrite(standard_error,
+		      "WARNING: Module ~w already imported from ~p~n"
 		      "Not importing again!~n",[M,ImportFile]),
 	    dont_import;
 	false ->
@@ -1165,7 +1166,8 @@ add_imported(M, F, ImportFile, [], Acc) ->
 remove_imported(Module,Imported) ->
     case lists:keysearch(Module,1,Imported) of
 	{value,{Module,_,ImportFiles}} ->
-	    io:fwrite("WARNING: Deleting data for module ~w imported from~n"
+	    io:fwrite(standard_error,
+		      "WARNING: Deleting data for module ~w imported from~n"
 		      "~p~n",[Module,ImportFiles]),
 	    lists:keydelete(Module,1,Imported);
 	false ->
diff --git a/lib/tools/src/make.erl b/lib/tools/src/make.erl
index 5cc8d47faaae..c34511a20910 100644
--- a/lib/tools/src/make.erl
+++ b/lib/tools/src/make.erl
@@ -90,7 +90,8 @@ read_emakefile(Emakefile,Opts) ->
 	    Mods = [filename:rootname(F) ||  F <- filelib:wildcard("*.erl")],
 	    [{Mods, Opts}];
 	{error,Other} ->
-	    io:format("make: Trouble reading 'Emakefile':~n~p~n",[Other]),
+	    io:format(standard_error, "make: Trouble reading 'Emakefile':~n~p~n",
+	              [Other]),
 	    error
     end.
 
@@ -145,7 +146,8 @@ get_opts_from_emakefile(Mods,Emakefile,Opts) ->
 	{error,enoent} ->
 	    [{Mods, Opts}];
 	{error,Other} ->
-	    io:format("make: Trouble reading 'Emakefile':~n~p~n",[Other]),
+	    io:format(standard_error, "make: Trouble reading 'Emakefile':~n~p~n",
+	              [Other]),
 	    error
     end.
 
diff --git a/lib/tools/src/xref_base.erl b/lib/tools/src/xref_base.erl
index 93f0e9c0c8c1..d79cb0cc0066 100644
--- a/lib/tools/src/xref_base.erl
+++ b/lib/tools/src/xref_base.erl
@@ -1506,7 +1506,8 @@ do_variables(State) ->
 		      _Else -> {[Name | P], U}
 		  end;
 	     ({{tmp, V}, _}, A) ->
-		  io:format("Bug in ~p: temporary ~p~n", [?MODULE, V]), A;
+		  io:format(standard_error, "Bug in ~p: temporary ~p~n", [?MODULE, V]),
+		  A;
 	     (_V, A) -> A
 	  end,
     {U,P} = foldl(Fun, {[],[]}, dict:to_list(State#xref.variables)),
@@ -1772,9 +1773,9 @@ message(true, What, Arg) ->
 	no_debug_info ->
 	    io:format("Skipping ~s (no debug information)~n", Arg);
 	unresolved_summary1 ->
-	    io:format("~p: 1 unresolved call~n", Arg);
+	    io:format(standard_error, "~p: 1 unresolved call~n", Arg);
 	unresolved_summary ->
-	    io:format("~p: ~p unresolved calls~n", Arg);
+	    io:format(standard_error, "~p: ~p unresolved calls~n", Arg);
 	jam ->
 	    io:format("Skipping ~s (probably JAM file)~n", [Arg]);
 	unreadable ->
@@ -1792,9 +1793,9 @@ message(true, What, Arg) ->
 	done ->
 	    io:format("done~n", Arg);
 	error ->
-	    io:format("error~n", Arg);
+	    io:format(standard_error, "error~n", Arg);
 	Else ->
-	    io:format("~p~n", [{Else,Arg}])
+	    io:format(standard_error, "~p~n", [{Else,Arg}])
     end;
 message(_, _, _) ->
     true.