Index: src/org/jruby/RubyInstanceConfig.java
===================================================================
--- src/org/jruby/RubyInstanceConfig.java	(revision 6067)
+++ src/org/jruby/RubyInstanceConfig.java	(working copy)
@@ -46,6 +46,7 @@
 import org.jruby.util.KCode;
 import org.jruby.util.NormalizedFile;
 import org.jruby.util.SafePropertyAccessor;
+import org.jruby.util.io.LineSeparator;
 
 public class RubyInstanceConfig {
 
@@ -97,6 +98,8 @@
 
     private ClassCache<Script> classCache;
 
+    private LineSeparator.STYLE lineSeparatorStyle;
+
     // from CommandlineParser
     private List<String> loadPaths = new ArrayList<String>();
     private StringBuffer inlineScript = new StringBuffer();
@@ -194,6 +197,15 @@
             System.err.println("Compatibility version `" + compatString + "' invalid; use RUBY1_8 or RUBY1_9. Using RUBY1_8.");
             compatVersion = CompatVersion.RUBY1_8;
         }
+        
+        String lineSeparatorStyleString = SafePropertyAccessor.getProperty("jruby.line.separator.style", "UNIX");
+        if (lineSeparatorStyleString.equalsIgnoreCase("WINDOWS")) {
+            lineSeparatorStyle = LineSeparator.STYLE.WINDOWS;
+        } else if (lineSeparatorStyleString.equalsIgnoreCase("MACOS")) {
+            lineSeparatorStyle = LineSeparator.STYLE.MACOS;
+        } else {
+            lineSeparatorStyle = LineSeparator.STYLE.UNIX;
+        }
 
         if (Ruby.isSecurityRestricted()) {
             compileMode = CompileMode.OFF;
@@ -353,7 +365,9 @@
                 .append("    jruby.objectspace.enabled=true|false\n")
                 .append("       Enable or disable ObjectSpace.each_object (default is disabled)\n")
                 .append("    jruby.launch.inproc=true|false\n")
-                .append("       Set in-process launching of e.g. system('ruby ...'). Default is true\n");
+                .append("       Set in-process launching of e.g. system('ruby ...'). Default is true\n")
+                .append("    jruby.line.separator.style=UNIX|WINDOWS|MACOS\n")
+                .append("       Set the line separator style of file outputs; Default is UNIX\n");
 
         return sb.toString();
     }
@@ -438,6 +452,10 @@
     public CompatVersion getCompatVersion() {
         return compatVersion;
     }
+    
+    public LineSeparator.STYLE getLineSeparatorStyle() {
+        return lineSeparatorStyle;
+    }
 
     public void setOutput(PrintStream newOutput) {
         output = newOutput;
Index: src/org/jruby/util/io/BaseLineSeparator.java
===================================================================
--- src/org/jruby/util/io/BaseLineSeparator.java	(revision 0)
+++ src/org/jruby/util/io/BaseLineSeparator.java	(revision 0)
@@ -0,0 +1,45 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+import java.nio.ByteBuffer;
+
+/**
+ *
+ * @author z2010269
+ */
+abstract class BaseLineSeparator implements LineSeparator {
+    ByteBuffer buffer;
+
+    public BaseLineSeparator(ByteBuffer buffer) {
+        this.buffer = buffer;
+    }
+    
+    abstract public int read();
+}
Index: src/org/jruby/util/io/LineSeparator.java
===================================================================
--- src/org/jruby/util/io/LineSeparator.java	(revision 0)
+++ src/org/jruby/util/io/LineSeparator.java	(revision 0)
@@ -0,0 +1,34 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+public interface LineSeparator {
+    public enum STYLE { UNIX, WINDOWS, MACOS };
+    public int read();
+}
Index: src/org/jruby/util/io/UnixLineSeparator.java
===================================================================
--- src/org/jruby/util/io/UnixLineSeparator.java	(revision 0)
+++ src/org/jruby/util/io/UnixLineSeparator.java	(revision 0)
@@ -0,0 +1,41 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+import java.nio.ByteBuffer;
+
+class UnixLineSeparator extends BaseLineSeparator {
+    public UnixLineSeparator(ByteBuffer buffer) {
+        super(buffer);
+    }
+
+    public int read() {
+        return buffer.get() & 0xFF;
+    }
+}
Index: src/org/jruby/util/io/LineSeparatorStyleFactory.java
===================================================================
--- src/org/jruby/util/io/LineSeparatorStyleFactory.java	(revision 0)
+++ src/org/jruby/util/io/LineSeparatorStyleFactory.java	(revision 0)
@@ -0,0 +1,57 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+import java.nio.ByteBuffer;
+import org.jruby.Ruby;
+
+class LineSeparatorStyleFactory {
+
+    static public LineSeparator newWindowsStyle(ByteBuffer buffer) {
+        return new WindowsLineSeparator(buffer);
+    }
+    
+    static public LineSeparator newUnixStyle(ByteBuffer buffer) {
+        return new UnixLineSeparator(buffer);
+    }
+
+    static public LineSeparator newMacOSStyle(ByteBuffer buffer) {
+        return new MacOSLineSeparator(buffer);
+    }
+    
+    static public LineSeparator newStyle(Ruby runtime, ByteBuffer buffer) {
+        LineSeparator.STYLE style = runtime.getInstanceConfig().getLineSeparatorStyle();
+        if (style == LineSeparator.STYLE.WINDOWS) {
+            return newWindowsStyle(buffer);
+        } else if (style == LineSeparator.STYLE.MACOS) {
+            return newMacOSStyle(buffer);
+        }
+        return newUnixStyle(buffer);
+    }
+}
Index: src/org/jruby/util/io/WindowsLineSeparator.java
===================================================================
--- src/org/jruby/util/io/WindowsLineSeparator.java	(revision 0)
+++ src/org/jruby/util/io/WindowsLineSeparator.java	(revision 0)
@@ -0,0 +1,52 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+import java.nio.ByteBuffer;
+
+class WindowsLineSeparator extends BaseLineSeparator {
+
+    public WindowsLineSeparator(ByteBuffer buffer) {
+        super(buffer);
+    }
+
+    public int read() {
+        final int curr = buffer.get() & 0xFF;
+        if (curr != '\r') {
+            return curr;
+        }
+        final int pos = buffer.position();
+        final int next = buffer.get() & 0xFF;
+        if (next == '\n') {
+            return next;
+        }
+        buffer.position(pos);
+        return curr;
+    }
+}
Index: src/org/jruby/util/io/ChannelStream.java
===================================================================
--- src/org/jruby/util/io/ChannelStream.java	(revision 6067)
+++ src/org/jruby/util/io/ChannelStream.java	(working copy)
@@ -73,6 +73,7 @@
     private ChannelDescriptor descriptor;
     private boolean blocking = true;
     protected int ungotc = -1;
+    private LineSeparator lineStyle;
 
     public ChannelStream(Ruby runtime, ChannelDescriptor descriptor, ModeFlags modes, FileDescriptor fileDescriptor) throws InvalidValueException {
         descriptor.checkNewModes(modes);
@@ -83,6 +84,7 @@
         this.buffer = ByteBuffer.allocate(BUFSIZE);
         buffer.flip();
         this.reading = true;
+        setLineStyle();
         
         // this constructor is used by fdopen, so we don't increment descriptor ref count
     }
@@ -98,6 +100,7 @@
         buffer = ByteBuffer.allocate(BUFSIZE);
         buffer.flip();
         this.reading = true;
+        setLineStyle();
     }
 
     public ChannelStream(Ruby runtime, ChannelDescriptor descriptor, ModeFlags modes) throws InvalidValueException {
@@ -109,7 +112,16 @@
         buffer = ByteBuffer.allocate(BUFSIZE);
         buffer.flip();
         this.reading = true;
+        setLineStyle();
     }
+    
+    private void setLineStyle() {
+        if (!modes.isBinary()) {
+            lineStyle = LineSeparatorStyleFactory.newStyle(runtime, buffer);            
+        } else {
+            lineStyle = LineSeparatorStyleFactory.newUnixStyle(buffer);
+        }
+    }
 
     public Ruby getRuntime() {
         return runtime;
@@ -571,7 +583,6 @@
     
     private int bufferedRead() throws IOException, BadDescriptorException {
         ensureRead();
-        
         if (!buffer.hasRemaining()) {
             buffer.clear();
             int read = descriptor.read(buffer);
@@ -582,7 +593,7 @@
                 return -1;
             }
         }
-        return buffer.get() & 0xFF;
+        return lineStyle.read();
     }
     
     /**
Index: src/org/jruby/util/io/MacOSLineSeparator.java
===================================================================
--- src/org/jruby/util/io/MacOSLineSeparator.java	(revision 0)
+++ src/org/jruby/util/io/MacOSLineSeparator.java	(revision 0)
@@ -0,0 +1,46 @@
+/*
+ ***** BEGIN LICENSE BLOCK *****
+ * Version: CPL 1.0/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Common Public
+ * License Version 1.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ *
+ * Copyright (C) 2008 Koichiro Ohba <koichiro@meadowy.org>
+ * 
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the CPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the CPL, the GPL or the LGPL.
+ ***** END LICENSE BLOCK *****/
+package org.jruby.util.io;
+
+import java.nio.ByteBuffer;
+
+public class MacOSLineSeparator extends BaseLineSeparator {
+
+    public MacOSLineSeparator(ByteBuffer buffer) {
+        super(buffer);
+    }
+
+    public int read() {
+        final int curr = buffer.get() & 0xFF;
+        if (curr != '\r') {
+            return curr;
+        }
+        return '\n';
+    }
+}
Index: src/org/jruby/RubyIO.java
===================================================================
--- src/org/jruby/RubyIO.java	(revision 6067)
+++ src/org/jruby/RubyIO.java	(working copy)
@@ -80,6 +80,7 @@
 import org.jruby.util.io.BadDescriptorException;
 import org.jruby.util.io.ChannelStream;
 import org.jruby.util.io.InvalidValueException;
+import org.jruby.util.io.LineSeparator;
 import org.jruby.util.io.PipeException;
 
 /**
@@ -1721,8 +1722,12 @@
         
         assert getRuntime().getGlobalVariables().getDefaultSeparator() instanceof RubyString;
         RubyString separator = (RubyString)getRuntime().getGlobalVariables().getDefaultSeparator();
-        
+
         if (args.length == 0) {
+            if (getRuntime().getInstanceConfig().getLineSeparatorStyle() == LineSeparator.STYLE.WINDOWS &&
+                  separator.equals(getRuntime().newString("\n")) == true) {
+                write(context, getRuntime().newString("\r").getByteList());
+            }
             write(context, separator.getByteList());
             return getRuntime().getNil();
         }
@@ -1744,6 +1749,10 @@
             write(context, line);
             
             if (line.length() == 0 || !line.endsWith(separator.getByteList())) {
+                if (getRuntime().getInstanceConfig().getLineSeparatorStyle() == LineSeparator.STYLE.WINDOWS &&
+                      separator.equals(getRuntime().newString("\n")) == true) {
+                    write(context, getRuntime().newString("\r").getByteList());
+                }
                 write(context, separator.getByteList());
             }
         }