Index: usr.bin/truss/extern.h
===================================================================
--- usr.bin/truss/extern.h
+++ usr.bin/truss/extern.h
@@ -34,6 +34,5 @@
 extern int print_line_prefix(struct trussinfo *);
 extern void setup_and_wait(struct trussinfo *, char **);
 extern void start_tracing(struct trussinfo *, pid_t);
-extern void restore_proc(int);
 extern void eventloop(struct trussinfo *);
 extern const char *ioctlname(unsigned long val);
Index: usr.bin/truss/main.c
===================================================================
--- usr.bin/truss/main.c
+++ usr.bin/truss/main.c
@@ -65,7 +65,6 @@
 int
 main(int ac, char **av)
 {
-	struct sigaction sa;
 	struct trussinfo *trussinfo;
 	char *fname;
 	char **command;
@@ -143,26 +142,11 @@
 			err(1, "cannot open %s", fname);
 	}
 
-	/*
-	 * If truss starts the process itself, it will ignore some signals --
-	 * they should be passed off to the process, which may or may not
-	 * exit.  If, however, we are examining an already-running process,
-	 * then we restore the event mask on these same signals.
-	 */
 	if (pid == 0) {
 		/* Start a command ourselves */
 		command = av;
 		setup_and_wait(trussinfo, command);
-		signal(SIGINT, SIG_IGN);
-		signal(SIGTERM, SIG_IGN);
-		signal(SIGQUIT, SIG_IGN);
 	} else {
-		sa.sa_handler = restore_proc;
-		sa.sa_flags = 0;
-		sigemptyset(&sa.sa_mask);
-		sigaction(SIGINT, &sa, NULL);
-		sigaction(SIGQUIT, &sa, NULL);
-		sigaction(SIGTERM, &sa, NULL);
 		start_tracing(trussinfo, pid);
 	}
 
Index: usr.bin/truss/setup.c
===================================================================
--- usr.bin/truss/setup.c
+++ usr.bin/truss/setup.c
@@ -61,16 +61,29 @@
 SET_DECLARE(procabi, struct procabi);
 
 static sig_atomic_t detaching;
+static pid_t new_child;
 
 static void	enter_syscall(struct trussinfo *, struct threadinfo *,
 		    struct ptrace_lwpinfo *);
 static void	new_proc(struct trussinfo *, pid_t, lwpid_t);
+static void	restore_proc(int);
 
+static void
+forward_signal(int signo)
+{
+
+	kill(new_child, signo);
+}
+
 /*
- * setup_and_wait() is called to start a process.  All it really does
- * is fork(), enable tracing in the child, and then exec the given
+ * setup_and_wait() is called to start a process.  First, it fork()s a new
+ * child, enables tracing in the child, and then execs the given
  * command.  At that point, the child process stops, and the parent
  * can wake up and deal with it.
+ *
+ * A signal handler is installed for SIGINT, SIGTERM, and SIGQUIT
+ * which forwards signals received by truss to the new child process
+ * so that truss is transparent from the shell's perspective.
  */
 void
 setup_and_wait(struct trussinfo *info, char *command[])
@@ -81,6 +94,7 @@
 	if (pid == -1)
 		err(1, "fork failed");
 	if (pid == 0) {	/* Child */
+		setpgid(0, 0);
 		ptrace(PT_TRACE_ME, 0, 0, 0);
 		execvp(command[0], command);
 		err(1, "execvp %s", command[0]);
@@ -90,6 +104,10 @@
 	if (waitpid(pid, NULL, 0) < 0)
 		err(1, "unexpect stop in waitpid");
 
+	new_child = pid;
+	signal(SIGINT, forward_signal);
+	signal(SIGTERM, forward_signal);
+	signal(SIGQUIT, forward_signal);
 	new_proc(info, pid, 0);
 }
 
@@ -99,8 +117,15 @@
 void
 start_tracing(struct trussinfo *info, pid_t pid)
 {
+	struct sigaction sa;
 	int ret, retry;
 
+	sa.sa_handler = restore_proc;
+	sa.sa_flags = 0;
+	sigemptyset(&sa.sa_mask);
+	sigaction(SIGINT, &sa, NULL);
+	sigaction(SIGQUIT, &sa, NULL);
+	sigaction(SIGTERM, &sa, NULL);
 	retry = 10;
 	do {
 		ret = ptrace(PT_ATTACH, pid, NULL, 0);
@@ -121,7 +146,7 @@
  * applies if truss was told to monitor an already-existing
  * process.
  */
-void
+static void
 restore_proc(int signo __unused)
 {