[stdlib] Open sys debug logs as utf8

This allows the use of ~ts/~tp/~tw in the formatting fun to
sys:handle_debug/4.

2 files changed, 3 insertions, 3 deletions

diff --git a/lib/stdlib/doc/src/sys.xml b/lib/stdlib/doc/src/sys.xml
index f24e42bcee..64d8789016 100644
--- a/lib/stdlib/doc/src/sys.xml
+++ b/lib/stdlib/doc/src/sys.xml
@@ -308,7 +308,7 @@
           format to the file. The events are formatted with a function that is 
           defined by the process that generated the event (with a call to
           <seealso marker="#handle_debug/4"><c>handle_debug/4</c></seealso>).
-        </p>
+	  The file is opened with encoding UTF-8.</p>
       </desc>
     </func>
 
diff --git a/lib/stdlib/src/sys.erl b/lib/stdlib/src/sys.erl
index a6ecf03716..1003c7c02b 100644
--- a/lib/stdlib/src/sys.erl
+++ b/lib/stdlib/src/sys.erl
@@ -525,7 +525,7 @@ debug_cmd({log_to_file, false}, Debug) ->
     {ok, NDebug};
 debug_cmd({log_to_file, FileName}, Debug) ->
     NDebug = close_log_file(Debug),
-    case file:open(FileName, [write]) of
+    case file:open(FileName, [write,{encoding,utf8}]) of
 	{ok, Fd} ->
 	    {ok, install_debug(log_to_file, Fd, NDebug)};
 	_Error ->
@@ -648,7 +648,7 @@ debug_options([{log, N} | T], Debug) when is_integer(N), N > 0 ->
 debug_options([statistics | T], Debug) ->
     debug_options(T, install_debug(statistics, init_stat(), Debug));
 debug_options([{log_to_file, FileName} | T], Debug) ->
-    case file:open(FileName, [write]) of
+    case file:open(FileName, [write,{encoding,utf8}]) of
 	{ok, Fd} ->
 	    debug_options(T, install_debug(log_to_file, Fd, Debug));
 	_Error ->