diff --git a/headers/private/kernel/debug.h b/headers/private/kernel/debug.h
index 768c410f50..33d08c2d53 100644
--- a/headers/private/kernel/debug.h
+++ b/headers/private/kernel/debug.h
@@ -42,7 +42,12 @@
 #	define ASSERT_PRINT(x, format...)	do { } while(0)
 #endif
 
+// command return value
+#define B_KDEBUG_ERROR	4
+
+// command flags
 #define B_KDEBUG_DONT_PARSE_ARGUMENTS	(0x01)
+#define B_KDEBUG_PIPE_FINAL_RERUN		(0x02)
 
 struct debugger_module_info {
 	module_info info;
@@ -74,6 +79,9 @@ extern bool debug_screen_output_enabled(void);
 extern void debug_stop_screen_debug_output(void);
 
 extern void	kputs(const char *string);
+extern void	kputs_unfiltered(const char *string);
+extern void kprintf_unfiltered(const char *format, ...)
+				__attribute__ ((format (__printf__, 1, 2)));
 extern void dprintf_no_syslog(const char *format, ...)
 				__attribute__ ((format (__printf__, 1, 2)));
 
diff --git a/src/system/kernel/debug/Jamfile b/src/system/kernel/debug/Jamfile
index 963b53fbbf..c6b6ad1c96 100644
--- a/src/system/kernel/debug/Jamfile
+++ b/src/system/kernel/debug/Jamfile
@@ -6,6 +6,7 @@ UsePrivateHeaders [ FDirName graphics vesa ] ;
 KernelMergeObject kernel_debug.o :
 	blue_screen.cpp
 	debug.cpp
+	debug_builtin_commands.cpp
 	debug_commands.cpp
 	debug_paranoia.cpp
 	debug_parser.cpp
diff --git a/src/system/kernel/debug/blue_screen.cpp b/src/system/kernel/debug/blue_screen.cpp
index ae6920e8dc..8b6a74f863 100644
--- a/src/system/kernel/debug/blue_screen.cpp
+++ b/src/system/kernel/debug/blue_screen.cpp
@@ -121,7 +121,7 @@ next_line(void)
 		// Use the paging mechanism: either, we're in the debugger, and a
 		// command is being executed, or we're currently showing boot debug
 		// output
-		const char *text = "Press key to continue, Q to quit";
+		const char *text = "Press key to continue, Q to quit, A to abort";
 		int32 length = strlen(text);
 		if (sScreen.x + length > sScreen.columns) {
 			// make sure we don't overwrite too much
@@ -136,8 +136,13 @@ next_line(void)
 		}
 
 		char c = blue_screen_getchar();
-		if (c == 'q')
+		if (c == 'q') {
 			sScreen.ignore_output = true;
+		} else if (c == 'a') {
+			abort_debugger_command();
+				// should not return
+			sScreen.ignore_output = true;
+		}
 
 		// remove on screen text again
 		sModule->fill_glyph(sScreen.columns - length, sScreen.y, length,
diff --git a/src/system/kernel/debug/debug.cpp b/src/system/kernel/debug/debug.cpp
index 375d949736..0691dd1573 100644
--- a/src/system/kernel/debug/debug.cpp
+++ b/src/system/kernel/debug/debug.cpp
@@ -9,7 +9,6 @@
 /*! This file contains the debugger and debug output facilities */
 
 #include "blue_screen.h"
-#include "gdb.h"
 
 #include <debug.h>
 #include <debug_paranoia.h>
@@ -35,7 +34,9 @@
 #include <string.h>
 #include <syslog.h>
 
+#include "debug_builtin_commands.h"
 #include "debug_commands.h"
+#include "debug_output_filter.h"
 #include "debug_variables.h"
 
 
@@ -67,6 +68,8 @@ static const char* sCurrentKernelDebuggerMessage;
 #define OUTPUT_BUFFER_SIZE 1024
 static char sOutputBuffer[OUTPUT_BUFFER_SIZE];
 static char sLastOutputBuffer[OUTPUT_BUFFER_SIZE];
+static DebugOutputFilter* sDebugOutputFilter = NULL;
+DefaultDebugOutputFilter gDefaultDebugOutputFilter;
 
 static void flush_pending_repeats(void);
 static void check_pending_repeats(void *data, int iter);
@@ -84,22 +87,80 @@ static const uint32 kMaxDebuggerModules = sizeof(sDebuggerModules)
 
 static char sLineBuffer[HISTORY_SIZE][LINE_BUFFER_SIZE] = { "", };
 static char sParseLine[LINE_BUFFER_SIZE];
-static char sFilter[64];
 static int32 sCurrentLine = 0;
 
 #define distance(a, b) ((a) < (b) ? (b) - (a) : (a) - (b))
 
 
+// #pragma mark - DebugOutputFilter
+
+
+DebugOutputFilter::DebugOutputFilter()
+{
+}
+
+
+DebugOutputFilter::~DebugOutputFilter()
+{
+}
+
+
+void
+DebugOutputFilter::PrintString(const char* string)
+{
+}
+
+
+void
+DebugOutputFilter::Print(const char* format, va_list args)
+{
+}
+
+
+void
+DefaultDebugOutputFilter::PrintString(const char* string)
+{
+	if (sSerialDebugEnabled)
+		arch_debug_serial_puts(string);
+	if (sBlueScreenEnabled || sDebugScreenEnabled)
+		blue_screen_puts(string);
+
+	for (uint32 i = 0; sSerialDebugEnabled && i < kMaxDebuggerModules; i++) {
+		if (sDebuggerModules[i] && sDebuggerModules[i]->debugger_puts)
+			sDebuggerModules[i]->debugger_puts(string, strlen(string));
+	}
+}
+
+
+void
+DefaultDebugOutputFilter::Print(const char* format, va_list args)
+{
+	vsnprintf(sOutputBuffer, OUTPUT_BUFFER_SIZE, format, args);
+	flush_pending_repeats();
+	PrintString(sOutputBuffer);
+}
+
+
+// #pragma mark -
+
+
+DebugOutputFilter*
+set_debug_output_filter(DebugOutputFilter* filter)
+{
+	DebugOutputFilter* oldFilter = sDebugOutputFilter;
+	sDebugOutputFilter = filter;
+	return oldFilter;
+}
+
+
 static void
 kputchar(char c)
 {
-	uint32 i;
-
 	if (sSerialDebugEnabled)
 		arch_debug_serial_putchar(c);
 	if (sBlueScreenEnabled || sDebugScreenEnabled)
 		blue_screen_putchar(c);
-	for (i = 0; sSerialDebugEnabled && i < kMaxDebuggerModules; i++)
+	for (uint32 i = 0; sSerialDebugEnabled && i < kMaxDebuggerModules; i++)
 		if (sDebuggerModules[i] && sDebuggerModules[i]->debugger_puts)
 			sDebuggerModules[i]->debugger_puts(&c, sizeof(c));
 }
@@ -108,15 +169,15 @@ kputchar(char c)
 void
 kputs(const char *s)
 {
-	uint32 i;
+	if (sDebugOutputFilter != NULL)
+		sDebugOutputFilter->PrintString(s);
+}
 
-	if (sSerialDebugEnabled)
-		arch_debug_serial_puts(s);
-	if (sBlueScreenEnabled || sDebugScreenEnabled)
-		blue_screen_puts(s);
-	for (i = 0; sSerialDebugEnabled && i < kMaxDebuggerModules; i++)
-		if (sDebuggerModules[i] && sDebuggerModules[i]->debugger_puts)
-			sDebuggerModules[i]->debugger_puts(s, strlen(s));
+
+void
+kputs_unfiltered(const char *s)
+{
+	gDefaultDebugOutputFilter.PrintString(s);
 }
 
 
@@ -630,124 +691,17 @@ kernel_debugger_loop(void)
 }
 
 
-static int
-cmd_reboot(int argc, char **argv)
-{
-	arch_cpu_shutdown(true);
-	return 0;
-		// I'll be really suprised if this line ever runs! ;-)
-}
-
-
-static int
-cmd_shutdown(int argc, char **argv)
-{
-	arch_cpu_shutdown(false);
-	return 0;
-}
-
-
-static int
-cmd_help(int argc, char **argv)
-{
-	debugger_command *command, *specified = NULL;
-	const char *start = NULL;
-	int32 startLength = 0;
-	bool ambiguous;
-
-	if (argc > 1) {
-		specified = find_debugger_command(argv[1], false, ambiguous);
-		if (specified == NULL) {
-			start = argv[1];
-			startLength = strlen(start);
-		}
-	}
-
-	if (specified != NULL) {
-		// only print out the help of the specified command (and all of its aliases)
-		kprintf("debugger command for \"%s\" and aliases:\n", specified->name);
-	} else if (start != NULL)
-		kprintf("debugger commands starting with \"%s\":\n", start);
-	else
-		kprintf("debugger commands:\n");
-
-	for (command = get_debugger_commands(); command != NULL;
-			command = command->next) {
-		if (specified && command->func != specified->func)
-			continue;
-		if (start != NULL && strncmp(start, command->name, startLength))
-			continue;
-
-		kprintf(" %-20s\t\t%s\n", command->name, command->description ? command->description : "-");
-	}
-
-	return 0;
-}
-
-
-static int
-cmd_continue(int argc, char **argv)
-{
-	return B_KDEBUG_QUIT;
-}
-
-
 static int
 cmd_dump_kdl_message(int argc, char **argv)
 {
 	if (sCurrentKernelDebuggerMessage) {
 		kputs(sCurrentKernelDebuggerMessage);
-		kputchar('\n');
+		kputs("\n");
 	}
 
 	return 0;
 }
 
-static int
-cmd_expr(int argc, char **argv)
-{
-	if (argc != 2) {
-		print_debugger_command_usage(argv[0]);
-		return 0;
-	}
-
-	uint64 result;
-	if (evaluate_debug_expression(argv[1], &result, false)) {
-		kprintf("%llu (0x%llx)\n", result, result);
-		set_debug_variable("_", result);
-	}
-
-	return 0;
-}
-
-
-static int
-cmd_filter(int argc, char **argv)
-{
-	if (argc != 2) {
-		sFilter[0] = '\0';
-		return 0;
-	}
-
-	strlcpy(sFilter, argv[1], sizeof(sFilter));
-	return 0;
-}
-
-
-static int
-cmd_error(int argc, char **argv)
-{
-	if (argc != 2) {
-		print_debugger_command_usage(argv[0]);
-		return 0;
-	}
-
-	int32 error = parse_expression(argv[1]);
-	kprintf("error 0x%lx: %s\n", error, strerror(error));
-
-	return 0;
-}
-
 
 static status_t
 syslog_sender(void *data)
@@ -1000,6 +954,8 @@ debug_early_boot_message(const char *string)
 status_t
 debug_init(kernel_args *args)
 {
+	new(&gDefaultDebugOutputFilter) DefaultDebugOutputFilter;
+
 	debug_paranoia_init();
 	return arch_debug_console_init(args);
 }
@@ -1008,43 +964,12 @@ debug_init(kernel_args *args)
 status_t
 debug_init_post_vm(kernel_args *args)
 {
-	add_debugger_command_etc("help", &cmd_help, "List all debugger commands",
-		"[name]\n"
-		"Lists all debugger commands or those starting with \"name\".\n", 0);
-	add_debugger_command_etc("reboot", &cmd_reboot, "Reboot the system",
-		"\n"
-		"Reboots the system.\n", 0);
-	add_debugger_command_etc("shutdown", &cmd_shutdown, "Shut down the system",
-		"\n"
-		"Shuts down the system.\n", 0);
-	add_debugger_command_etc("gdb", &cmd_gdb, "Connect to remote gdb",
-		"\n"
-		"Connects to a remote gdb connected to the serial port.\n", 0);
-	add_debugger_command_etc("continue", &cmd_continue, "Leave kernel debugger",
-		"\n"
-		"Leaves kernel debugger.\n", 0);
-	add_debugger_command_alias("exit", "continue", "Same as \"continue\"");
-	add_debugger_command_alias("es", "continue", "Same as \"continue\"");
 	add_debugger_command_etc("message", &cmd_dump_kdl_message,
 		"Reprint the message printed when entering KDL",
 		"\n"
 		"Reprints the message printed when entering KDL.\n", 0);
-	add_debugger_command_etc("expr", &cmd_expr,
-		"Evaluates the given expression and prints the result",
-		"<expression>\n"
-		"Evaluates the given expression and prints the result.\n",
-		B_KDEBUG_DONT_PARSE_ARGUMENTS);
-	add_debugger_command_etc("filter", &cmd_filter,
-		"Filters output of all debugger commands",
-		"<pattern>\n"
-		"Filters out all debug output of commands that does not match the\n"
-		"specified pattern. If no pattern is given, it is removed\n", 0);
-	add_debugger_command_etc("error", &cmd_error,
-		"Prints a human-readable description for an error code",
-		"<error>\n"
-		"Prints a human-readable description for the given numeric error\n"
-		"code.\n"
-		"  <error>  - The numeric error code.\n", 0);
+
+	debug_builtin_commands_init();
 
 	debug_variables_init();
 	frame_buffer_console_init(args);
@@ -1181,6 +1106,8 @@ kernel_debugger(const char *message)
 			sBlueScreenEnabled = true;
 	}
 
+	sDebugOutputFilter = &gDefaultDebugOutputFilter;
+
 	if (message)
 		kprintf("PANIC: %s\n", message);
 
@@ -1196,6 +1123,8 @@ kernel_debugger(const char *message)
 	call_modules_hook(false);
 	set_dprintf_enabled(dprintfState);
 
+	sDebugOutputFilter = NULL;
+
 	sBlueScreenEnabled = false;
 	atomic_add(&inDebugger, -1);
 	restore_interrupts(state);
@@ -1354,21 +1283,22 @@ dprintf_no_syslog(const char *format, ...)
 void
 kprintf(const char *format, ...)
 {
-	va_list args;
-
-	// ToDo: don't print anything if the debugger is not running!
-
-	va_start(args, format);
-	vsnprintf(sOutputBuffer, OUTPUT_BUFFER_SIZE, format, args);
-	va_end(args);
-
-	if (in_command_invocation() && sFilter[0]) {
-		if (strstr(sOutputBuffer, sFilter) == NULL)
-			return;
+	if (sDebugOutputFilter != NULL) {
+		va_list args;
+		va_start(args, format);
+		sDebugOutputFilter->Print(format, args);
+		va_end(args);
 	}
+}
 
-	flush_pending_repeats();
-	kputs(sOutputBuffer);
+
+void
+kprintf_unfiltered(const char *format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	gDefaultDebugOutputFilter.Print(format, args);
+	va_end(args);
 }
 
 
diff --git a/src/system/kernel/debug/debug_builtin_commands.cpp b/src/system/kernel/debug/debug_builtin_commands.cpp
new file mode 100644
index 0000000000..04d615c90a
--- /dev/null
+++ b/src/system/kernel/debug/debug_builtin_commands.cpp
@@ -0,0 +1,318 @@
+/*
+ * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de
+ * Copyright 2002-2008, Axel Dörfler, axeld@pinc-software.de
+ * Distributed under the terms of the MIT License.
+ *
+ * Copyright 2001, Travis Geiselbrecht. All rights reserved.
+ * Distributed under the terms of the NewOS License.
+ */
+
+#include "debug_builtin_commands.h"
+
+#include <ctype.h>
+#include <debug.h>
+#include <kernel.h>
+
+#include "debug_commands.h"
+#include "gdb.h"
+
+
+static int
+cmd_reboot(int argc, char **argv)
+{
+	arch_cpu_shutdown(true);
+	return 0;
+		// I'll be really suprised if this line ever runs! ;-)
+}
+
+
+static int
+cmd_shutdown(int argc, char **argv)
+{
+	arch_cpu_shutdown(false);
+	return 0;
+}
+
+
+static int
+cmd_help(int argc, char **argv)
+{
+	debugger_command *command, *specified = NULL;
+	const char *start = NULL;
+	int32 startLength = 0;
+	bool ambiguous;
+
+	if (argc > 1) {
+		specified = find_debugger_command(argv[1], false, ambiguous);
+		if (specified == NULL) {
+			start = argv[1];
+			startLength = strlen(start);
+		}
+	}
+
+	if (specified != NULL) {
+		// only print out the help of the specified command (and all of its aliases)
+		kprintf("debugger command for \"%s\" and aliases:\n", specified->name);
+	} else if (start != NULL)
+		kprintf("debugger commands starting with \"%s\":\n", start);
+	else
+		kprintf("debugger commands:\n");
+
+	for (command = get_debugger_commands(); command != NULL;
+			command = command->next) {
+		if (specified && command->func != specified->func)
+			continue;
+		if (start != NULL && strncmp(start, command->name, startLength))
+			continue;
+
+		kprintf(" %-20s\t\t%s\n", command->name, command->description ? command->description : "-");
+	}
+
+	return 0;
+}
+
+
+static int
+cmd_continue(int argc, char **argv)
+{
+	return B_KDEBUG_QUIT;
+}
+
+
+static int
+cmd_expr(int argc, char **argv)
+{
+	if (argc != 2) {
+		print_debugger_command_usage(argv[0]);
+		return 0;
+	}
+
+	uint64 result;
+	if (evaluate_debug_expression(argv[1], &result, false)) {
+		kprintf("%llu (0x%llx)\n", result, result);
+		set_debug_variable("_", result);
+	}
+
+	return 0;
+}
+
+
+static int
+cmd_error(int argc, char **argv)
+{
+	if (argc != 2) {
+		print_debugger_command_usage(argv[0]);
+		return 0;
+	}
+
+	int32 error = parse_expression(argv[1]);
+	kprintf("error 0x%lx: %s\n", error, strerror(error));
+
+	return 0;
+}
+
+
+static int
+cmd_head(int argc, char** argv)
+{
+	debugger_command_pipe_segment* segment
+		= get_current_debugger_command_pipe_segment();
+	if (segment == NULL) {
+		kprintf_unfiltered("%s can only be run as part of a pipe!\n", argv[0]);
+		return B_KDEBUG_ERROR;
+	}
+
+	struct user_data {
+		uint64	max_lines;
+		uint64	lines;
+	};
+	user_data* userData = (user_data*)segment->user_data;
+
+	if (segment->invocations == 0) {
+		if (argc != 3) {
+			print_debugger_command_usage(argv[0]);
+			return B_KDEBUG_ERROR;
+		}
+
+		if (!evaluate_debug_expression(argv[1], &userData->max_lines, false))
+			return B_KDEBUG_ERROR;
+		userData->lines = 0;
+	}
+
+	if (++userData->lines <= userData->max_lines) {
+		kputs(argv[2]);
+		kputs("\n");
+	}
+
+	return 0;
+}
+
+
+static int
+cmd_grep(int argc, char** argv)
+{
+	bool caseSensitive = true;
+	bool inverseMatch = false;
+
+	int argi = 1;
+	for (; argi < argc; argi++) {
+		const char* arg = argv[argi];
+		if (arg[0] != '-')
+			break;
+
+		for (int32 i = 1; arg[i] != '\0'; i++) {
+			if (arg[i] == 'i') {
+				caseSensitive = false;
+			} else if (arg[i] == 'v') {
+				inverseMatch = true;
+			} else {
+				print_debugger_command_usage(argv[0]);
+				return B_KDEBUG_ERROR;
+			}
+		}
+	}
+
+	if (argc - argi != 2) {
+		print_debugger_command_usage(argv[0]);
+		return B_KDEBUG_ERROR;
+	}
+
+	const char* pattern = argv[argi++];
+	const char* line = argv[argi++];
+
+	bool match;
+	if (caseSensitive) {
+		match = strstr(line, pattern) != NULL;
+	} else {
+		match = false;
+		int32 lineLen = strlen(line);
+		int32 patternLen = strlen(pattern);
+		for (int32 i = 0; i <= lineLen - patternLen; i++) {
+			// This is rather slow, but should be OK for our purposes.
+			if (strncasecmp(line + i, pattern, patternLen) == 0) {
+				match = true;
+				break;
+			}
+		}
+	}
+
+	if (match != inverseMatch) {
+		kputs(line);
+		kputs("\n");
+	}
+
+	return 0;
+}
+
+
+static int
+cmd_wc(int argc, char** argv)
+{
+	debugger_command_pipe_segment* segment
+		= get_current_debugger_command_pipe_segment();
+	if (segment == NULL) {
+		kprintf_unfiltered("%s can only be run as part of a pipe!\n", argv[0]);
+		return B_KDEBUG_ERROR;
+	}
+
+	struct user_data {
+		uint64	lines;
+		uint64	words;
+		uint64	chars;
+	};
+	user_data* userData = (user_data*)segment->user_data;
+
+	if (segment->invocations == 0) {
+		if (argc != 2) {
+			print_debugger_command_usage(argv[0]);
+			return B_KDEBUG_ERROR;
+		}
+
+		userData->lines = 0;
+		userData->words = 0;
+		userData->chars = 0;
+	}
+
+	const char* line = argv[1];
+	if (line == NULL) {
+		// last run -- print results
+		kprintf("%10lld %10lld %10lld\n", userData->lines, userData->words,
+			userData->chars);
+		return 0;
+	}
+
+	userData->lines++;
+	userData->chars++;
+		// newline
+
+	// count words and chars in this line
+	bool inWord = false;
+	for (; *line != '\0'; line++) {
+		userData->chars++;
+		if ((isspace(*line) != 0) == inWord) {
+			inWord = !inWord;
+			if (inWord)
+				userData->words++;
+		}
+	}
+
+	return 0;
+}
+
+
+// #pragma mark -
+
+
+void
+debug_builtin_commands_init()
+{
+	add_debugger_command_etc("help", &cmd_help, "List all debugger commands",
+		"[name]\n"
+		"Lists all debugger commands or those starting with \"name\".\n", 0);
+	add_debugger_command_etc("reboot", &cmd_reboot, "Reboot the system",
+		"\n"
+		"Reboots the system.\n", 0);
+	add_debugger_command_etc("shutdown", &cmd_shutdown, "Shut down the system",
+		"\n"
+		"Shuts down the system.\n", 0);
+	add_debugger_command_etc("gdb", &cmd_gdb, "Connect to remote gdb",
+		"\n"
+		"Connects to a remote gdb connected to the serial port.\n", 0);
+	add_debugger_command_etc("continue", &cmd_continue, "Leave kernel debugger",
+		"\n"
+		"Leaves kernel debugger.\n", 0);
+	add_debugger_command_alias("exit", "continue", "Same as \"continue\"");
+	add_debugger_command_alias("es", "continue", "Same as \"continue\"");
+	add_debugger_command_etc("expr", &cmd_expr,
+		"Evaluates the given expression and prints the result",
+		"<expression>\n"
+		"Evaluates the given expression and prints the result.\n",
+		B_KDEBUG_DONT_PARSE_ARGUMENTS);
+	add_debugger_command_etc("error", &cmd_error,
+		"Prints a human-readable description for an error code",
+		"<error>\n"
+		"Prints a human-readable description for the given numeric error\n"
+		"code.\n"
+		"  <error>  - The numeric error code.\n", 0);
+	add_debugger_command_etc("head", &cmd_head,
+		"Prints only the first lines of output from another command",
+		"<maxLines>\n"
+		"Should be used in a command pipe. It prints only the first\n"
+		"<maxLines> lines of output from the previous command in the pipe and\n"
+		"silently discards the rest of the output.\n", 0);
+	add_debugger_command_etc("grep", &cmd_grep,
+		"Filters output from another command",
+		"[ -i ] [ -v ] <pattern>\n"
+		"Should be used in a command pipe. It filters all output from the\n"
+		"previous command in the pipe according to the given pattern.\n"
+		"When \"-v\" is specified, only those lines are printed that don't\n"
+		"match the given pattern, otherwise only those that do match. When\n"
+		"\"-i\" is specified, the pattern is matched case insensitive,\n"
+		"otherwise case sensitive.\n", 0);
+	add_debugger_command_etc("wc", &cmd_wc,
+		"Counts the lines, words, and characters of another command's output",
+		"<maxLines>\n"
+		"Should be used in a command pipe. It prints how many lines, words,\n"
+		"and characters the output of the previous command consists of.\n",
+		B_KDEBUG_PIPE_FINAL_RERUN);
+}
diff --git a/src/system/kernel/debug/debug_builtin_commands.h b/src/system/kernel/debug/debug_builtin_commands.h
new file mode 100644
index 0000000000..d99f16e78f
--- /dev/null
+++ b/src/system/kernel/debug/debug_builtin_commands.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _KERNEL_DEBUG_BUILTIN_COMMANDS_H
+#define _KERNEL_DEBUG_BUILTIN_COMMANDS_H
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void debug_builtin_commands_init();
+
+#ifdef __cplusplus
+}	// extern "C"
+#endif
+
+
+#endif	// _KERNEL_DEBUG_BUILTIN_COMMANDS_H
diff --git a/src/system/kernel/debug/debug_commands.cpp b/src/system/kernel/debug/debug_commands.cpp
index b8288dd9e2..414475c01c 100644
--- a/src/system/kernel/debug/debug_commands.cpp
+++ b/src/system/kernel/debug/debug_commands.cpp
@@ -10,6 +10,7 @@
 #include "debug_commands.h"
 
 #include <setjmp.h>
+#include <stdio.h>
 #include <string.h>
 
 #include <KernelExport.h>
@@ -19,16 +20,172 @@
 #include <thread.h>
 #include <util/AutoLock.h>
 
+#include "debug_output_filter.h"
 #include "debug_variables.h"
 
 
+#define INVOKE_COMMAND_FAULT	1
+#define INVOKE_COMMAND_ERROR	2
+
+static const int32 kMaxInvokeCommandDepth = 5;
+static const int32 kOutputBufferSize = 1024;
+
 static spinlock sSpinlock = 0;
 
 static struct debugger_command *sCommands;
 
-static jmp_buf sInvokeCommandEnv;
+static jmp_buf sInvokeCommandEnv[kMaxInvokeCommandDepth];
+static int32 sInvokeCommandLevel = 0;
 static bool sInvokeCommandDirectly = false;
 static bool sInCommand = false;
+static char sOutputBuffers[MAX_DEBUGGER_COMMAND_PIPE_LENGTH][kOutputBufferSize];
+static debugger_command_pipe* sCurrentPipe;
+static int32 sCurrentPipeSegment;
+
+
+static int invoke_pipe_segment(debugger_command_pipe* pipe, int32 index,
+	char* argument);
+
+
+class PipeDebugOutputFilter : public DebugOutputFilter {
+public:
+	PipeDebugOutputFilter()
+	{
+	}
+
+	PipeDebugOutputFilter(debugger_command_pipe* pipe, int32 segment,
+			char* buffer, size_t bufferSize)
+		:
+		fPipe(pipe),
+		fSegment(segment),
+		fBuffer(buffer),
+		fBufferCapacity(bufferSize - 1),
+		fBufferSize(0)
+	{
+	}
+
+	virtual void PrintString(const char* string)
+	{
+		if (fPipe->broken)
+			return;
+
+		size_t size = strlen(string);
+		while (const char* newLine = strchr(string, '\n')) {
+			size_t length = newLine - string;
+			_Append(string, length);
+
+			// invoke command
+			fBuffer[fBufferSize] = '\0';
+			invoke_pipe_segment(fPipe, fSegment + 1, fBuffer);
+
+			fBufferSize = 0;
+
+			string = newLine + 1;
+			size -= length + 1;
+		}
+
+		_Append(string, size);
+
+		if (fBufferSize == fBufferCapacity) {
+			// buffer is full, but contains no newline -- execute anyway
+			invoke_pipe_segment(fPipe, fSegment + 1, fBuffer);
+			fBufferSize = 0;
+		}
+	}
+
+	virtual void Print(const char* format, va_list args)
+	{
+		if (fPipe->broken)
+			return;
+
+		// print directly into the buffer
+		fBufferSize += vsnprintf(fBuffer + fBufferSize,
+			fBufferCapacity - fBufferSize, format, args);
+
+		// execute every complete line
+		fBuffer[fBufferSize] = '\0';
+		char* line = fBuffer;
+
+		while (char* newLine = strchr(line, '\n')) {
+			// invoke command
+			*newLine = '\0';
+			invoke_pipe_segment(fPipe, fSegment + 1, line);
+
+			line = newLine + 1;
+		}
+
+		size_t left = fBuffer + fBufferSize - line;
+
+		if (left == fBufferCapacity) {
+			// buffer is full, but contains no newline -- execute anyway
+			invoke_pipe_segment(fPipe, fSegment + 1, fBuffer);
+			left = 0;
+		}
+
+		if (left > 0)
+			memmove(fBuffer, line, left);
+
+		fBufferSize = left;
+	}
+
+private:
+	void _Append(const char* string, size_t length)
+	{
+		size_t toAppend = min_c(length, fBufferCapacity - fBufferSize);
+		memcpy(fBuffer + fBufferSize, string, toAppend);
+		fBufferSize += length;
+	}
+
+private:
+	debugger_command_pipe*	fPipe;
+	int32					fSegment;
+	char*					fBuffer;
+	size_t					fBufferCapacity;
+	size_t					fBufferSize;
+};
+
+
+static PipeDebugOutputFilter sPipeOutputFilters[
+	MAX_DEBUGGER_COMMAND_PIPE_LENGTH - 1];
+
+
+static int
+invoke_pipe_segment(debugger_command_pipe* pipe, int32 index, char* argument)
+{
+	// set debug output
+	DebugOutputFilter* oldFilter = set_debug_output_filter(
+		index == pipe->segment_count - 1
+			? &gDefaultDebugOutputFilter : &sPipeOutputFilters[index]);
+
+	// set last command argument
+	debugger_command_pipe_segment& segment = pipe->segments[index];
+	if (index > 0)
+		segment.argv[segment.argc - 1] = argument;
+
+	// invoke command
+	int32 oldIndex = sCurrentPipeSegment;
+	sCurrentPipeSegment = index;
+
+	int result = invoke_debugger_command(segment.command, segment.argc,
+		segment.argv);
+	segment.invocations++;
+
+	sCurrentPipeSegment = oldIndex;
+
+	// reset debug output
+	set_debug_output_filter(oldFilter);
+
+	if (result == B_KDEBUG_ERROR) {
+		pipe->broken = true;
+
+		// Abort the previous pipe segment execution. The complete pipe is
+		// aborted iteratively this way.
+		if (index > 0)
+			abort_debugger_command();
+	}
+
+	return result;
+}
 
 
 debugger_command*
@@ -98,9 +255,10 @@ invoke_debugger_command(struct debugger_command *command, int argc, char** argv)
 	// intercept invocations with "--help" and directly print the usage text
 	// If we know the command's usage text, intercept "--help" invocations
 	// and print it directly.
-	if (argc == 2 && strcmp(argv[1], "--help") == 0 && command->usage != NULL) {
-		kprintf("usage: %s ", command->name);
-		kputs(command->usage);
+	if (argc == 2 && argv[1] != NULL && strcmp(argv[1], "--help") == 0
+			&& command->usage != NULL) {
+		kprintf_unfiltered("usage: %s ", command->name);
+		kputs_unfiltered(command->usage);
 		return 0;
 	}
 
@@ -117,30 +275,96 @@ invoke_debugger_command(struct debugger_command *command, int argc, char** argv)
 
 	sInCommand = true;
 
-	if (setjmp(sInvokeCommandEnv) == 0) {
-		int result;
-		thread->fault_handler = (addr_t)&&error;
-		// Fake goto to trick the compiler not to optimize the code at the label
-		// away.
-		if (!thread)
-			goto error;
+	switch (setjmp(sInvokeCommandEnv[sInvokeCommandLevel++])) {
+		case 0:
+			int result;
+			thread->fault_handler = (addr_t)&&error;
+			// Fake goto to trick the compiler not to optimize the code at the label
+			// away.
+			if (!thread)
+				goto error;
 
-		result = command->func(argc, argv);
+			result = command->func(argc, argv);
 
-		thread->fault_handler = oldFaultHandler;
-		sInCommand = false;
-		return result;
+			thread->fault_handler = oldFaultHandler;
+			sInvokeCommandLevel--;
+			sInCommand = false;
+			return result;
 
 error:
-		longjmp(sInvokeCommandEnv, 1);
-			// jump into the else branch
-	} else {
-		kprintf("\n[*** READ/WRITE FAULT ***]\n");
+			// jump to INVOKE_COMMAND_FAULT case, cleaning up the stack
+			longjmp(sInvokeCommandEnv[--sInvokeCommandLevel],
+				INVOKE_COMMAND_FAULT);
+
+		case INVOKE_COMMAND_FAULT:
+			kprintf_unfiltered("\n[*** READ/WRITE FAULT ***]\n");
+			break;
+		case INVOKE_COMMAND_ERROR:
+			// command aborted (no page fault)
+			break;
 	}
 
 	thread->fault_handler = oldFaultHandler;
 	sInCommand = false;
-	return 0;
+	return B_KDEBUG_ERROR;
+}
+
+
+/*!	Aborts the currently executed debugger command (in fact the complete pipe),
+	unless direct command invocation has been set. If successful, the function
+	won't return.
+*/
+void
+abort_debugger_command()
+{
+	if (!sInvokeCommandDirectly && sInvokeCommandLevel > 0) {
+		longjmp(sInvokeCommandEnv[--sInvokeCommandLevel],
+			INVOKE_COMMAND_ERROR);
+	}
+}
+
+
+int
+invoke_debugger_command_pipe(debugger_command_pipe* pipe)
+{
+	debugger_command_pipe* oldPipe = sCurrentPipe;
+	sCurrentPipe = pipe;
+
+	// prepare outputs
+	// TODO: If a pipe is invoked in a pipe, outputs will clash.
+	int32 segments = pipe->segment_count;
+	for (int32 i = 0; i < segments - 1; i++) {
+		new(&sPipeOutputFilters[i]) PipeDebugOutputFilter(pipe, i,
+			sOutputBuffers[i], kOutputBufferSize);
+	}
+
+	int result = invoke_pipe_segment(pipe, 0, NULL);
+
+	// perform final rerun for all commands that want it
+	for (int32 i = 1; result != B_KDEBUG_ERROR && i < segments; i++) {
+		debugger_command_pipe_segment& segment = pipe->segments[i];
+		if ((segment.command->flags & B_KDEBUG_PIPE_FINAL_RERUN) != 0)
+			result = invoke_pipe_segment(pipe, i, NULL);
+	}
+
+	sCurrentPipe = oldPipe;
+
+	return result;
+}
+
+
+debugger_command_pipe*
+get_current_debugger_command_pipe()
+{
+	return sCurrentPipe;
+}
+
+
+debugger_command_pipe_segment*
+get_current_debugger_command_pipe_segment()
+{
+	return sCurrentPipe != NULL
+		? &sCurrentPipe->segments[sCurrentPipeSegment] : NULL;
 }
 
 
@@ -234,8 +458,8 @@ print_debugger_command_usage(const char* commandName)
 	// directly print the usage text, if we know it, otherwise invoke the
 	// command with "--help"
 	if (command->usage != NULL) {
-		kprintf("usage: %s ", command->name);
-		kputs(command->usage);
+		kprintf_unfiltered("usage: %s ", command->name);
+		kputs_unfiltered(command->usage);
 	} else {
 		char* args[3] = { NULL, "--help", NULL };
 		invoke_debugger_command(command, 2, args);
diff --git a/src/system/kernel/debug/debug_commands.h b/src/system/kernel/debug/debug_commands.h
index d7d8497f34..15f6e00809 100644
--- a/src/system/kernel/debug/debug_commands.h
+++ b/src/system/kernel/debug/debug_commands.h
@@ -9,14 +9,33 @@
 #include <SupportDefs.h>
 
 
-struct debugger_command {
+#define MAX_DEBUGGER_COMMAND_PIPE_LENGTH	8
+
+
+typedef struct debugger_command {
 	struct debugger_command* next;
 	int				(*func)(int, char **);
 	const char*		name;
 	const char*		description;
 	const char*		usage;
 	uint32			flags;
-};
+} debugger_command;
+
+typedef struct debugger_command_pipe_segment {
+	int32				index;
+	debugger_command*	command;
+	int					argc;
+	char**				argv;
+	int32				invocations;
+	uint32				user_data[8];	// can be used by the command
+} debugger_command_pipe_segment;
+
+typedef struct debugger_command_pipe {
+	int32							segment_count;
+	debugger_command_pipe_segment	segments[MAX_DEBUGGER_COMMAND_PIPE_LENGTH];
+	bool							broken;
+} debugger_command_pipe;
+
 
 #ifdef __cplusplus
 extern "C" {
@@ -30,6 +49,11 @@ bool in_command_invocation(void);
 
 int invoke_debugger_command(struct debugger_command *command, int argc,
 	char** argv);
+void abort_debugger_command();
+
+int invoke_debugger_command_pipe(debugger_command_pipe* pipe);
+debugger_command_pipe* get_current_debugger_command_pipe();
+debugger_command_pipe_segment* get_current_debugger_command_pipe_segment();
 
 debugger_command* get_debugger_commands();
 void sort_debugger_commands();
diff --git a/src/system/kernel/debug/debug_output_filter.h b/src/system/kernel/debug/debug_output_filter.h
new file mode 100644
index 0000000000..7a7ede25fc
--- /dev/null
+++ b/src/system/kernel/debug/debug_output_filter.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _KERNEL_DEBUG_OUTPUT_FILTER_H
+#define _KERNEL_DEBUG_OUTPUT_FILTER_H
+
+#include <stdarg.h>
+
+#include <SupportDefs.h>
+
+
+class DebugOutputFilter {
+public:
+	DebugOutputFilter();
+	virtual ~DebugOutputFilter();
+
+	virtual void PrintString(const char* string);
+	virtual void Print(const char* format, va_list args);
+};
+
+class DefaultDebugOutputFilter : public DebugOutputFilter {
+public:
+	virtual void PrintString(const char* string);
+	virtual void Print(const char* format, va_list args);
+};
+
+
+extern DefaultDebugOutputFilter gDefaultDebugOutputFilter;
+
+
+DebugOutputFilter* set_debug_output_filter(DebugOutputFilter* filter);
+
+
+#endif	// _KERNEL_DEBUG_OUTPUT_FILTER_H
diff --git a/src/system/kernel/debug/debug_parser.cpp b/src/system/kernel/debug/debug_parser.cpp
index 5a69a5ae38..4c5a232610 100644
--- a/src/system/kernel/debug/debug_parser.cpp
+++ b/src/system/kernel/debug/debug_parser.cpp
@@ -21,7 +21,7 @@
 /*
 	Grammar:
 
-	commandLine	:= command | ( "(" expression ")" )
+	commandLine	:= commandPipe | ( "(" expression ")" )
 	expression	:= term | assignment
 	assignment	:= variable ( "=" | "+=" | "-=" | "*=" | "/=" | "%=" )
 				   expression
@@ -33,6 +33,7 @@
 	variable	:= identifier
 	identifier	:= ( "_" | "a" - "z" | "A" - "Z" )
 				   ( "_" | "a" - "z" | "A" - "Z" | "0" - "9" )*
+	commandPipe	:= command ( "|" command )*
 	command		:= identifier argument*
 	argument	:= ( "(" expression ")" ) | ( "[" commandLine "]" )
 				   | unquotedString | quotedString
@@ -87,6 +88,8 @@ enum {
 	TOKEN_OPENING_BRACE			= '{',
 	TOKEN_CLOSING_BRACE			= '}',
 
+	TOKEN_PIPE					= '|',
+
 	TOKEN_STRING				= '"',
 	TOKEN_UNKNOWN				= '?',
 	TOKEN_NONE					= ' ',
@@ -125,8 +128,9 @@ static void
 parse_exception(const char* message, int32 position)
 {
 	if (sNextJumpBufferIndex == 0) {
-		kprintf("parse_exception(): No jump buffer!\n");
-		kprintf("exception: \"%s\", position: %lu\n", message, position);
+		kprintf_unfiltered("parse_exception(): No jump buffer!\n");
+		kprintf_unfiltered("exception: \"%s\", position: %lu\n", message,
+			position);
 		return;
 	}
 
@@ -345,6 +349,7 @@ public:
 			case ')':
 			case '[':
 			case ']':
+			case '|':
 				fCurrentToken.SetTo(fCurrentChar, 1, _CurrentPos(),
 					*fCurrentChar);
 				fCurrentChar++;
@@ -470,7 +475,9 @@ class ExpressionParser {
 
  private:
 			uint64				_ParseExpression();
-			uint64				_ParseCommand(int& returnCode);
+			uint64				_ParseCommandPipe(int& returnCode);
+			void				_ParseCommand(
+									debugger_command_pipe_segment& segment);
 			bool				_ParseArgument(int& argc, char** argv);
 			void				_GetUnparsedArgument(int& argc, char** argv);
 			void				_AddArgument(int& argc, char** argv,
@@ -533,7 +540,7 @@ ExpressionParser::EvaluateCommand(const char* expressionString,
 		// no assignment, so let's assume it's a command
 		fTokenizer.SetTo(expressionString);
 		fTokenizer.SetCommandMode(true);
-		value = _ParseCommand(returnCode);
+		value = _ParseCommandPipe(returnCode);
 	}
 
 	if (token.type != TOKEN_END_OF_LINE)
@@ -621,7 +628,39 @@ ExpressionParser::_ParseExpression()
 
 
 uint64
-ExpressionParser::_ParseCommand(int& returnCode)
+ExpressionParser::_ParseCommandPipe(int& returnCode)
+{
+	debugger_command_pipe* pipe = (debugger_command_pipe*)allocate_temp_storage(
+		sizeof(debugger_command_pipe));
+
+	pipe->segment_count = 0;
+	pipe->broken = false;
+
+	do {
+		if (pipe->segment_count >= MAX_DEBUGGER_COMMAND_PIPE_LENGTH)
+			parse_exception("Pipe too long", fTokenizer.NextToken().position);
+
+		debugger_command_pipe_segment& segment
+			= pipe->segments[pipe->segment_count];
+		segment.index = pipe->segment_count++;
+
+		_ParseCommand(segment);
+
+	} while (fTokenizer.NextToken().type == TOKEN_PIPE);
+
+	fTokenizer.RewindToken();
+
+	// invoke the pipe
+	returnCode = invoke_debugger_command_pipe(pipe);
+
+	free_temp_storage(pipe);
+
+	return get_debug_variable("_", 0);
+}
+
+
+void
+ExpressionParser::_ParseCommand(debugger_command_pipe_segment& segment)
 {
 	fTokenizer.SetCommandMode(false);
 	const Token& token = _EatToken(TOKEN_IDENTIFIER);
@@ -663,12 +702,17 @@ ExpressionParser::_ParseCommand(int& returnCode)
 		}
 	}
 
-	// invoke the command
-	returnCode = invoke_debugger_command(command, argc, argv);
+	if (segment.index > 0) {
+		if (argc >= kMaxArgumentCount)
+			parse_exception("too many arguments for command", 0);
+		else
+			argc++;
+	}
 
-	free_temp_storage(argv);
-
-	return get_debug_variable("_", 0);
+	segment.command = command;
+	segment.argc = argc;
+	segment.argv = argv;
+	segment.invocations = 0;
 }
 
 
@@ -694,7 +738,7 @@ ExpressionParser::_ParseArgument(int& argc, char** argv)
 		{
 			// this starts a sub command
 			int returnValue;
-			uint64 value = _ParseCommand(returnValue);
+			uint64 value = _ParseCommandPipe(returnValue);
 			_EatToken(TOKEN_CLOSING_BRACKET);
 
 			snprintf(sTempBuffer, sizeof(sTempBuffer), "%llu", value);
@@ -709,6 +753,7 @@ ExpressionParser::_ParseArgument(int& argc, char** argv)
 
 		case TOKEN_CLOSING_PARENTHESIS:
 		case TOKEN_CLOSING_BRACKET:
+		case TOKEN_PIPE:
 			// those don't belong to us
 			fTokenizer.RewindToken();
 			return false;
@@ -755,6 +800,10 @@ ExpressionParser::_GetUnparsedArgument(int& argc, char** argv)
 				else
 					done = true;
 				break;
+			case TOKEN_PIPE:
+				if (parentheses == 0 && brackets == 0)
+					done = true;
+				break;
 			case TOKEN_END_OF_LINE:
 				done = true;
 				break;
@@ -764,8 +813,15 @@ ExpressionParser::_GetUnparsedArgument(int& argc, char** argv)
 	int32 endPosition = fTokenizer.CurrentToken().position;
 	fTokenizer.RewindToken();
 
-	_AddArgument(argc, argv, fTokenizer.String() + startPosition,
-		endPosition - startPosition);
+	// add the argument only, if it's not just all spaces
+	const char* arg = fTokenizer.String() + startPosition;
+	int32 argLen = endPosition - startPosition;
+	bool allSpaces = true;
+	for (int32 i = 0; allSpaces && i < argLen; i++)
+		allSpaces = isspace(arg[i]);
+
+	if (!allSpaces)
+		_AddArgument(argc, argv, arg, argLen);
 }
 
 
@@ -944,7 +1000,7 @@ ExpressionParser::_ParseAtom()
 
 	fTokenizer.SetCommandMode(true);
 	int returnValue;
-	uint64 value = _ParseCommand(returnValue);
+	uint64 value = _ParseCommandPipe(returnValue);
 	fTokenizer.SetCommandMode(false);
 
 	_EatToken(TOKEN_CLOSING_BRACKET);
@@ -975,8 +1031,8 @@ bool
 evaluate_debug_expression(const char* expression, uint64* _result, bool silent)
 {
 	if (sNextJumpBufferIndex >= kJumpBufferCount) {
-		kprintf("evaluate_debug_expression(): Out of jump buffers for "
-			"exception handling\n");
+		kprintf_unfiltered("evaluate_debug_expression(): Out of jump buffers "
+			"for exception handling\n");
 		return 0;
 	}
 
@@ -994,10 +1050,10 @@ evaluate_debug_expression(const char* expression, uint64* _result, bool silent)
 		success = false;
 		if (!silent) {
 			if (sExceptionPosition >= 0) {
-				kprintf("%s, at position: %d, in expression: %s\n",
+				kprintf_unfiltered("%s, at position: %d, in expression: %s\n",
 					sExceptionMessage, sExceptionPosition, expression);
 			} else
-				kprintf("%s", sExceptionMessage);
+				kprintf_unfiltered("%s", sExceptionMessage);
 		}
 	}
 
@@ -1017,7 +1073,7 @@ int
 evaluate_debug_command(const char* commandLine)
 {
 	if (sNextJumpBufferIndex >= kJumpBufferCount) {
-		kprintf("evaluate_debug_command(): Out of jump buffers for "
+		kprintf_unfiltered("evaluate_debug_command(): Out of jump buffers for "
 			"exception handling\n");
 		return 0;
 	}
@@ -1031,10 +1087,10 @@ evaluate_debug_command(const char* commandLine)
 		ExpressionParser().EvaluateCommand(commandLine, returnCode);
 	} else {
 		if (sExceptionPosition >= 0) {
-			kprintf("%s, at position: %d, in command line: %s\n",
+			kprintf_unfiltered("%s, at position: %d, in command line: %s\n",
 				sExceptionMessage, sExceptionPosition, commandLine);
 		} else
-			kprintf("%s", sExceptionMessage);
+			kprintf_unfiltered("%s", sExceptionMessage);
 	}
 
 	sNextJumpBufferIndex--;