diff --git a/bin/sh/eval.c b/bin/sh/eval.c
index 5e2b951d80d9..4195255c7cd0 100644
--- a/bin/sh/eval.c
+++ b/bin/sh/eval.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: eval.c,v 1.51 2000/02/09 20:26:53 christos Exp $	*/
+/*	$NetBSD: eval.c,v 1.52 2000/05/13 20:50:14 elric Exp $	*/
 
 /*-
  * Copyright (c) 1993
@@ -41,10 +41,13 @@
 #if 0
 static char sccsid[] = "@(#)eval.c	8.9 (Berkeley) 6/8/95";
 #else
-__RCSID("$NetBSD: eval.c,v 1.51 2000/02/09 20:26:53 christos Exp $");
+__RCSID("$NetBSD: eval.c,v 1.52 2000/05/13 20:50:14 elric Exp $");
 #endif
 #endif /* not lint */
 
+#include <errno.h>
+#include <fcntl.h>
+#include <paths.h>
 #include <signal.h>
 #include <unistd.h>
 
@@ -52,6 +55,7 @@ __RCSID("$NetBSD: eval.c,v 1.51 2000/02/09 20:26:53 christos Exp $");
  * Evaluate a command.
  */
 
+#include "main.h"
 #include "shell.h"
 #include "nodes.h"
 #include "syntax.h"
@@ -588,6 +592,7 @@ out:
 }
 
 
+int vforked = 0;
 
 /*
  * Execute a simple command.
@@ -627,6 +632,7 @@ evalcommand(cmd, flags, backcmd)
 	(void) &flags;
 #endif
 
+	vforked = 0;
 	/* First expand the arguments. */
 	TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
 	setstackmark(&smark);
@@ -736,8 +742,62 @@ evalcommand(cmd, flags, backcmd)
 			if (pipe(pip) < 0)
 				error("Pipe call failed");
 		}
-		if (forkshell(jp, cmd, mode) != 0)
-			goto parent;	/* at end of routine */
+#ifdef DO_SHAREDVFORK
+		/* It is essential that if DO_SHAREDVFORK is defined that the
+		 * child's address space is actually shared with the parent as
+		 * we rely on this.
+		 */
+		if (cmdentry.cmdtype == CMDNORMAL) {
+			pid_t	pid;
+
+			INTOFF;
+			vforked = 1;
+			switch (pid = vfork()) {
+			case -1:
+				TRACE(("Vfork failed, errno=%d", errno));
+				INTON;
+				error("Cannot vfork");
+				break;
+			case 0:
+				/* Make sure that exceptions only unwind to
+				 * after the vfork(2)
+				 */
+				if (setjmp(jmploc.loc)) {
+					if (exception == EXSHELLPROC) {
+						/* We can't progress with the vfork,
+						 * so, set vforked = 2 so the parent
+						 * knows, and _exit();
+						 */
+						vforked = 2;
+						_exit(0);
+					} else {
+						_exit(exerrno);
+					}
+				}
+				savehandler = handler;
+				handler = &jmploc;
+				forkchild(jp, cmd, mode, vforked);
+				break;
+			default:
+				handler = savehandler;	/* restore from vfork(2) */
+				if (vforked == 2) {
+					vforked = 0;
+					waitpid(pid, NULL, 0);
+					/* We need to progress in a normal fork fashion */
+					goto normal_fork;
+				}
+				vforked = 0;
+				forkparent(jp, cmd, mode, pid);
+				goto parent;
+			}
+		} else {
+normal_fork:
+#endif
+			if (forkshell(jp, cmd, mode) != 0)
+				goto parent;	/* at end of routine */
+#ifdef DO_SHAREDVFORK
+		}
+#endif
 		if (flags & EV_BACKCMD) {
 			FORCEINTON;
 			close(pip[0]);
@@ -862,12 +922,12 @@ cmddone:
 #ifdef DEBUG
 		trputs("normal command:  ");  trargs(argv);
 #endif
-		clearredir();
-		redirect(cmd->ncmd.redirect, 0);
+		clearredir(vforked?REDIR_VFORK:0);
+		redirect(cmd->ncmd.redirect, vforked?REDIR_VFORK:0);
 		for (sp = varlist.list ; sp ; sp = sp->next)
 			setvareq(sp->text, VEXPORT|VSTACK);
 		envp = environment();
-		shellexec(argv, envp, pathval(), cmdentry.u.index);
+		shellexec(argv, envp, pathval(), cmdentry.u.index, vforked);
 	}
 	goto out;
 
@@ -892,7 +952,6 @@ out:
 }
 
 
-
 /*
  * Search for a command.  This is called before we fork so that the
  * location of the command will be available in the parent as well as
@@ -1022,7 +1081,7 @@ execcmd(argc, argv)
 		optschanged();
 		for (sp = cmdenviron; sp ; sp = sp->next)
 			setvareq(sp->text, VEXPORT|VSTACK);
-		shellexec(argv + 1, environment(), pathval(), 0);
+		shellexec(argv + 1, environment(), pathval(), 0, 0);
 	}
 	return 0;
 }
diff --git a/bin/sh/exec.c b/bin/sh/exec.c
index 59ebb0b1f8a6..a4a7a946544e 100644
--- a/bin/sh/exec.c
+++ b/bin/sh/exec.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: exec.c,v 1.27 1999/07/09 03:05:49 christos Exp $	*/
+/*	$NetBSD: exec.c,v 1.28 2000/05/13 20:50:14 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,15 +41,17 @@
 #if 0
 static char sccsid[] = "@(#)exec.c	8.4 (Berkeley) 6/8/95";
 #else
-__RCSID("$NetBSD: exec.c,v 1.27 1999/07/09 03:05:49 christos Exp $");
+__RCSID("$NetBSD: exec.c,v 1.28 2000/05/13 20:50:14 elric Exp $");
 #endif
 #endif /* not lint */
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 /*
@@ -102,7 +104,7 @@ STATIC int builtinloc = -1;		/* index in path of %builtin, or -1 */
 int exerrno = 0;			/* Last exec error */
 
 
-STATIC void tryexec __P((char *, char **, char **));
+STATIC void tryexec __P((char *, char **, char **, int));
 STATIC void execinterp __P((char **, char **));
 STATIC void printentry __P((struct tblentry *, int));
 STATIC void clearcmdentry __P((int));
@@ -117,22 +119,23 @@ STATIC void delete_cmd_entry __P((void));
  */
 
 void
-shellexec(argv, envp, path, idx)
+shellexec(argv, envp, path, idx, vforked)
 	char **argv, **envp;
 	const char *path;
 	int idx;
+	int vforked;
 {
 	char *cmdname;
 	int e;
 
 	if (strchr(argv[0], '/') != NULL) {
-		tryexec(argv[0], argv, envp);
+		tryexec(argv[0], argv, envp, vforked);
 		e = errno;
 	} else {
 		e = ENOENT;
 		while ((cmdname = padvance(&path, argv[0])) != NULL) {
 			if (--idx < 0 && pathopt == NULL) {
-				tryexec(cmdname, argv, envp);
+				tryexec(cmdname, argv, envp, vforked);
 				if (errno != ENOENT && errno != ENOTDIR)
 					e = errno;
 			}
@@ -158,10 +161,11 @@ shellexec(argv, envp, path, idx)
 
 
 STATIC void
-tryexec(cmd, argv, envp)
+tryexec(cmd, argv, envp, vforked)
 	char *cmd;
 	char **argv;
 	char **envp;
+	int vforked;
 	{
 	int e;
 #ifndef BSD
@@ -177,6 +181,13 @@ tryexec(cmd, argv, envp)
 #endif
 	e = errno;
 	if (e == ENOEXEC) {
+		if (vforked) {
+			/* We are currently vfork(2)ed, so raise an
+			 * exception, and evalcommand will try again
+			 * with a normal fork(2).
+			 */
+			exraise(EXSHELLPROC);
+		}
 		initshellproc();
 		setinputfile(cmd, 0);
 		commandname = arg0 = savestr(argv[0]);
diff --git a/bin/sh/exec.h b/bin/sh/exec.h
index 3c0394951a42..ddfc1fcd31e7 100644
--- a/bin/sh/exec.h
+++ b/bin/sh/exec.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: exec.h,v 1.15 1999/07/09 03:05:50 christos Exp $	*/
+/*	$NetBSD: exec.h,v 1.16 2000/05/13 20:50:14 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -60,7 +60,7 @@ struct cmdentry {
 extern const char *pathopt;	/* set by padvance */
 extern int exerrno;		/* last exec error */
 
-void shellexec __P((char **, char **, const char *, int))
+void shellexec __P((char **, char **, const char *, int, int))
     __attribute__((noreturn));
 char *padvance __P((const char **, const char *));
 int hashcmd __P((int, char **));
diff --git a/bin/sh/input.c b/bin/sh/input.c
index f119f1ac9138..c44c2c0771a7 100644
--- a/bin/sh/input.c
+++ b/bin/sh/input.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: input.c,v 1.32 1999/07/09 03:05:50 christos Exp $	*/
+/*	$NetBSD: input.c,v 1.33 2000/05/13 20:50:14 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,7 +41,7 @@
 #if 0
 static char sccsid[] = "@(#)input.c	8.3 (Berkeley) 6/9/95";
 #else
-__RCSID("$NetBSD: input.c,v 1.32 1999/07/09 03:05:50 christos Exp $");
+__RCSID("$NetBSD: input.c,v 1.33 2000/05/13 20:50:14 elric Exp $");
 #endif
 #endif /* not lint */
 
@@ -506,10 +506,22 @@ popallfiles() {
 /*
  * Close the file(s) that the shell is reading commands from.  Called
  * after a fork is done.
+ *
+ * Takes one arg, vfork, which tells it to not modify its global vars
+ * as it is still running in the parent.
  */
 
 void
-closescript() {
+closescript(int vforked) {
+	if (vforked) {
+		struct parsefile *pf;
+
+		for (pf=parsefile; pf != &basepf; pf=pf->prev)
+			close(pf->fd);
+		if (parsefile->fd > 0)
+			close(parsefile->fd);
+		return;
+	}
 	popallfiles();
 	if (parsefile->fd > 0) {
 		close(parsefile->fd);
diff --git a/bin/sh/input.h b/bin/sh/input.h
index 93f9ecfcf8e6..b45ec3f0d8ae 100644
--- a/bin/sh/input.h
+++ b/bin/sh/input.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: input.h,v 1.10 1999/07/09 03:05:50 christos Exp $	*/
+/*	$NetBSD: input.h,v 1.11 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -61,6 +61,6 @@ void setinputfd __P((int, int));
 void setinputstring __P((char *, int));
 void popfile __P((void));
 void popallfiles __P((void));
-void closescript __P((void));
+void closescript __P((int));
 
 #define pgetc_macro()	(--parsenleft >= 0? *parsenextc++ : preadbuffer())
diff --git a/bin/sh/jobs.c b/bin/sh/jobs.c
index 3f8f04b2d823..63240f5f0967 100644
--- a/bin/sh/jobs.c
+++ b/bin/sh/jobs.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: jobs.c,v 1.32 1999/08/31 08:58:47 mycroft Exp $	*/
+/*	$NetBSD: jobs.c,v 1.33 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,7 +41,7 @@
 #if 0
 static char sccsid[] = "@(#)jobs.c	8.5 (Berkeley) 5/4/95";
 #else
-__RCSID("$NetBSD: jobs.c,v 1.32 1999/08/31 08:58:47 mycroft Exp $");
+__RCSID("$NetBSD: jobs.c,v 1.33 2000/05/13 20:50:15 elric Exp $");
 #endif
 #endif /* not lint */
 
@@ -149,9 +149,9 @@ setjobctl(on)
 			return;
 		}
 #endif
-		setsignal(SIGTSTP);
-		setsignal(SIGTTOU);
-		setsignal(SIGTTIN);
+		setsignal(SIGTSTP, 0);
+		setsignal(SIGTTOU, 0);
+		setsignal(SIGTTIN, 0);
 		setpgid(0, rootpid);
 #ifdef OLD_TTY_DRIVER
 		ioctl(2, TIOCSPGRP, (char *)&rootpid);
@@ -165,9 +165,9 @@ setjobctl(on)
 #else
 		tcsetpgrp(2, initialpgrp);
 #endif
-		setsignal(SIGTSTP);
-		setsignal(SIGTTOU);
-		setsignal(SIGTTIN);
+		setsignal(SIGTSTP, 0);
+		setsignal(SIGTTOU, 0);
+		setsignal(SIGTTIN, 0);
 	}
 	jobctl = on;
 }
@@ -574,81 +574,33 @@ forkshell(jp, n, mode)
 {
 	int pid;
 	int pgrp;
-	const char *devnull = _PATH_DEVNULL;
-	const char *nullerr = "Can't open %s";
 
 	TRACE(("forkshell(%%%d, 0x%lx, %d) called\n", jp - jobtab, (long)n,
 	    mode));
 	INTOFF;
-	pid = fork();
-	if (pid == -1) {
+	switch (pid = fork()) {
+	case -1:
 		TRACE(("Fork failed, errno=%d\n", errno));
 		INTON;
 		error("Cannot fork");
+		break;
+	case 0:
+		forkchild(jp, n, mode, 0);
+		return 0;
+	default:
+		return forkparent(jp, n, mode, pid);
 	}
-	if (pid == 0) {
-		struct job *p;
-		int wasroot;
-		int i;
+}
 
-		TRACE(("Child shell %d\n", getpid()));
-		wasroot = rootshell;
-		rootshell = 0;
-		for (i = njobs, p = jobtab ; --i >= 0 ; p++)
-			if (p->used)
-				freejob(p);
-		closescript();
-		INTON;
-		clear_traps();
-#if JOBS
-		jobctl = 0;		/* do job control only in root shell */
-		if (wasroot && mode != FORK_NOJOB && mflag) {
-			if (jp == NULL || jp->nprocs == 0)
-				pgrp = getpid();
-			else
-				pgrp = jp->ps[0].pid;
-			setpgid(0, pgrp);
-			if (mode == FORK_FG) {
-				/*** this causes superfluous TIOCSPGRPS ***/
-#ifdef OLD_TTY_DRIVER
-				if (ioctl(2, TIOCSPGRP, (char *)&pgrp) < 0)
-					error("TIOCSPGRP failed, errno=%d", errno);
-#else
-				if (tcsetpgrp(2, pgrp) < 0)
-					error("tcsetpgrp failed, errno=%d", errno);
-#endif
-			}
-			setsignal(SIGTSTP);
-			setsignal(SIGTTOU);
-		} else if (mode == FORK_BG) {
-			ignoresig(SIGINT);
-			ignoresig(SIGQUIT);
-			if ((jp == NULL || jp->nprocs == 0) &&
-			    ! fd0_redirected_p ()) {
-				close(0);
-				if (open(devnull, O_RDONLY) != 0)
-					error(nullerr, devnull);
-			}
-		}
-#else
-		if (mode == FORK_BG) {
-			ignoresig(SIGINT);
-			ignoresig(SIGQUIT);
-			if ((jp == NULL || jp->nprocs == 0) &&
-			    ! fd0_redirected_p ()) {
-				close(0);
-				if (open(devnull, O_RDONLY) != 0)
-					error(nullerr, devnull);
-			}
-		}
-#endif
-		if (wasroot && iflag) {
-			setsignal(SIGINT);
-			setsignal(SIGQUIT);
-			setsignal(SIGTERM);
-		}
-		return pid;
-	}
+int
+forkparent(jp, n, mode, pid)
+	union node *n;
+	struct job *jp;
+	int mode;
+	pid_t pid;
+{
+	int pgrp;
+	
 	if (rootshell && mode != FORK_NOJOB && mflag) {
 		if (jp == NULL || jp->nprocs == 0)
 			pgrp = pid;
@@ -671,6 +623,81 @@ forkshell(jp, n, mode)
 	return pid;
 }
 
+void
+forkchild(jp, n, mode, vforked)
+	union node *n;
+	struct job *jp;
+	int mode;
+	int vforked;
+{
+	struct job *p;
+	int wasroot;
+	int i;
+	int pgrp;
+	const char *devnull = _PATH_DEVNULL;
+	const char *nullerr = "Can't open %s";
+
+	TRACE(("Child shell %d\n", getpid()));
+	wasroot = rootshell;
+	if (!vforked) {
+		rootshell = 0;
+		for (i = njobs, p = jobtab ; --i >= 0 ; p++)
+			if (p->used)
+				freejob(p);
+	}
+	closescript(vforked);
+	INTON;
+	clear_traps(vforked);
+#if JOBS
+	if (!vforked)
+		jobctl = 0;		/* do job control only in root shell */
+	if (wasroot && mode != FORK_NOJOB && mflag) {
+		if (jp == NULL || jp->nprocs == 0)
+			pgrp = getpid();
+		else
+			pgrp = jp->ps[0].pid;
+		setpgid(0, pgrp);
+		if (mode == FORK_FG) {
+			/*** this causes superfluous TIOCSPGRPS ***/
+#ifdef OLD_TTY_DRIVER
+			if (ioctl(2, TIOCSPGRP, (char *)&pgrp) < 0)
+				error("TIOCSPGRP failed, errno=%d", errno);
+#else
+			if (tcsetpgrp(2, pgrp) < 0)
+				error("tcsetpgrp failed, errno=%d", errno);
+#endif
+		}
+		setsignal(SIGTSTP, vforked);
+		setsignal(SIGTTOU, vforked);
+	} else if (mode == FORK_BG) {
+		ignoresig(SIGINT, vforked);
+		ignoresig(SIGQUIT, vforked);
+		if ((jp == NULL || jp->nprocs == 0) &&
+		    ! fd0_redirected_p ()) {
+			close(0);
+			if (open(devnull, O_RDONLY) != 0)
+				error(nullerr, devnull);
+		}
+	}
+#else
+	if (mode == FORK_BG) {
+		ignoresig(SIGINT, vforked);
+		ignoresig(SIGQUIT, vforked);
+		if ((jp == NULL || jp->nprocs == 0) &&
+		    ! fd0_redirected_p ()) {
+			close(0);
+			if (open(devnull, O_RDONLY) != 0)
+				error(nullerr, devnull);
+		}
+	}
+#endif
+	if (wasroot && iflag) {
+		setsignal(SIGINT, vforked);
+		setsignal(SIGQUIT, vforked);
+		setsignal(SIGTERM, vforked);
+	}
+}
+
 
 
 /*
diff --git a/bin/sh/jobs.h b/bin/sh/jobs.h
index d5ec14530e3e..4a26ee9f6656 100644
--- a/bin/sh/jobs.h
+++ b/bin/sh/jobs.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: jobs.h,v 1.9 1997/10/15 13:23:10 christos Exp $	*/
+/*	$NetBSD: jobs.h,v 1.10 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -88,6 +88,8 @@ int waitcmd __P((int, char **));
 int jobidcmd __P((int, char **));
 struct job *makejob __P((union node *, int));
 int forkshell __P((struct job *, union node *, int));
+void forkchild __P((struct job *jp, union node *n, int mode, int vfork));
+int forkparent __P((struct job *jp, union node *n, int mode, pid_t pid));
 int waitforjob __P((struct job *));
 int stoppedjobs __P((void));
 char *commandtext __P((union node *));
diff --git a/bin/sh/main.c b/bin/sh/main.c
index 20e44967f31f..5804b237f1f0 100644
--- a/bin/sh/main.c
+++ b/bin/sh/main.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: main.c,v 1.36 2000/04/14 05:54:20 simonb Exp $	*/
+/*	$NetBSD: main.c,v 1.37 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -46,7 +46,7 @@ __COPYRIGHT("@(#) Copyright (c) 1991, 1993\n\
 #if 0
 static char sccsid[] = "@(#)main.c	8.7 (Berkeley) 7/19/95";
 #else
-__RCSID("$NetBSD: main.c,v 1.36 2000/04/14 05:54:20 simonb Exp $");
+__RCSID("$NetBSD: main.c,v 1.37 2000/05/13 20:50:15 elric Exp $");
 #endif
 #endif /* not lint */
 
@@ -205,7 +205,7 @@ state3:
 		int i;
 
 		for (i = 0; i < SIGSSIZE; i++)
-		    setsignal(sigs[i]);
+		    setsignal(sigs[i], 0);
 	}
 
 	if (minusc)
diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index f79d8f0881c4..3a782de314ac 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: redir.c,v 1.20 1999/02/04 16:17:39 christos Exp $	*/
+/*	$NetBSD: redir.c,v 1.21 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,7 +41,7 @@
 #if 0
 static char sccsid[] = "@(#)redir.c	8.2 (Berkeley) 5/4/95";
 #else
-__RCSID("$NetBSD: redir.c,v 1.20 1999/02/04 16:17:39 christos Exp $");
+__RCSID("$NetBSD: redir.c,v 1.21 2000/05/13 20:50:15 elric Exp $");
 #endif
 #endif /* not lint */
 
@@ -120,6 +120,9 @@ redirect(redir, flags)
 		memory[i] = 0;
 	memory[1] = flags & REDIR_BACKQ;
 	if (flags & REDIR_PUSH) {
+		/* We don't have to worry about REDIR_VFORK here, as
+		 * flags & REDIR_PUSH is never true if REDIR_VFORK is set.
+		 */
 		sv = ckmalloc(sizeof (struct redirtab));
 		for (i = 0 ; i < 10 ; i++)
 			sv->renamed[i] = EMPTY;
@@ -335,7 +338,7 @@ RESET {
 }
 
 SHELLPROC {
-	clearredir();
+	clearredir(0);
 }
 
 #endif
@@ -351,7 +354,9 @@ fd0_redirected_p () {
  */
 
 void
-clearredir() {
+clearredir(vforked)
+	int vforked;
+{
 	struct redirtab *rp;
 	int i;
 
@@ -360,7 +365,8 @@ clearredir() {
 			if (rp->renamed[i] >= 0) {
 				close(rp->renamed[i]);
 			}
-			rp->renamed[i] = EMPTY;
+			if (!vforked)
+				rp->renamed[i] = EMPTY;
 		}
 	}
 }
diff --git a/bin/sh/redir.h b/bin/sh/redir.h
index 44eecc76c59f..553d69e30d39 100644
--- a/bin/sh/redir.h
+++ b/bin/sh/redir.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: redir.h,v 1.10 1996/10/16 15:45:18 christos Exp $	*/
+/*	$NetBSD: redir.h,v 1.11 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,11 +41,12 @@
 /* flags passed to redirect */
 #define REDIR_PUSH 01		/* save previous values of file descriptors */
 #define REDIR_BACKQ 02		/* save the command output in memory */
+#define REDIR_VFORK 04		/* running under vfork(2), be careful */
 
 union node;
 void redirect __P((union node *, int));
 void popredir __P((void));
 int fd0_redirected_p __P((void));
-void clearredir __P((void));
+void clearredir __P((int));
 int copyfd __P((int, int));
 
diff --git a/bin/sh/shell.h b/bin/sh/shell.h
index 95012d1ee288..b6f269947ed4 100644
--- a/bin/sh/shell.h
+++ b/bin/sh/shell.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: shell.h,v 1.10 1996/10/16 15:21:49 christos Exp $	*/
+/*	$NetBSD: shell.h,v 1.11 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -46,6 +46,8 @@
  *	define SYSV if you are running under System V.
  *	define DEBUG=1 to compile in debugging (set global "debug" to turn on)
  *	define DEBUG=2 to compile in and turn on debugging.
+ *	define DO_SHAREDVFORK to indicate that vfork(2) shares its address
+ *	       with its parent.
  *
  * When debugging is on, debugging info will be written to $HOME/trace and
  * a quit signal will generate a core dump.
@@ -57,6 +59,12 @@
 #define BSD 1
 #endif
 
+#ifndef DO_SHAREDVFORK
+#if __NetBSD_Version__ >= 104000000
+#define DO_SHAREDVFORK
+#endif
+#endif
+
 #ifdef __STDC__
 typedef void *pointer;
 #ifndef NULL
diff --git a/bin/sh/trap.c b/bin/sh/trap.c
index 13e62f3a3ec2..9087caca051f 100644
--- a/bin/sh/trap.c
+++ b/bin/sh/trap.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: trap.c,v 1.22 2000/01/27 23:39:41 christos Exp $	*/
+/*	$NetBSD: trap.c,v 1.23 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,7 +41,7 @@
 #if 0
 static char sccsid[] = "@(#)trap.c	8.5 (Berkeley) 6/5/95";
 #else
-__RCSID("$NetBSD: trap.c,v 1.22 2000/01/27 23:39:41 christos Exp $");
+__RCSID("$NetBSD: trap.c,v 1.23 2000/05/13 20:50:15 elric Exp $");
 #endif
 #endif /* not lint */
 
@@ -121,7 +121,7 @@ trapcmd(argc, argv)
 			ckfree(trap[signo]);
 		trap[signo] = action;
 		if (signo != 0)
-			setsignal(signo);
+			setsignal(signo, 0);
 		INTON;
 		ap++;
 	}
@@ -131,20 +131,26 @@ trapcmd(argc, argv)
 
 
 /*
- * Clear traps on a fork.
+ * Clear traps on a fork or vfork.
+ * Takes one arg vfork, to tell it to not be destructive of
+ * the parents variables.
  */
 
 void
-clear_traps() {
+clear_traps(vforked)
+	int vforked;
+{
 	char **tp;
 
 	for (tp = trap ; tp <= &trap[NSIG] ; tp++) {
 		if (*tp && **tp) {	/* trap not NULL or SIG_IGN */
 			INTOFF;
-			ckfree(*tp);
-			*tp = NULL;
+			if (!vforked) {
+				ckfree(*tp);
+				*tp = NULL;
+			}
 			if (tp != &trap[0])
-				setsignal(tp - trap);
+				setsignal(tp - trap, vforked);
 			INTON;
 		}
 	}
@@ -158,12 +164,13 @@ clear_traps() {
  */
 
 long
-setsignal(signo)
+setsignal(signo, vforked)
 	int signo;
+	int vforked;
 {
 	int action;
 	sig_t sigact = SIG_DFL;
-	char *t;
+	char *t, tsig;
 
 	if ((t = trap[signo]) == NULL)
 		action = S_DFL;
@@ -171,7 +178,7 @@ setsignal(signo)
 		action = S_CATCH;
 	else
 		action = S_IGN;
-	if (rootshell && action == S_DFL) {
+	if (rootshell && !vforked && action == S_DFL) {
 		switch (signo) {
 		case SIGINT:
 			if (iflag || minusc || sflag == 0)
@@ -202,7 +209,8 @@ setsignal(signo)
 	}
 
 	t = &sigmode[signo - 1];
-	if (*t == 0) {
+	tsig = *t;
+	if (tsig == 0) {
 		/*
 		 * current setting unknown
 		 */
@@ -217,21 +225,22 @@ setsignal(signo)
 		if (sigact == SIG_IGN) {
 			if (mflag && (signo == SIGTSTP ||
 			     signo == SIGTTIN || signo == SIGTTOU)) {
-				*t = S_IGN;	/* don't hard ignore these */
+				tsig = S_IGN;	/* don't hard ignore these */
 			} else
-				*t = S_HARD_IGN;
+				tsig = S_HARD_IGN;
 		} else {
-			*t = S_RESET;	/* force to be set */
+			tsig = S_RESET;	/* force to be set */
 		}
 	}
-	if (*t == S_HARD_IGN || *t == action)
+	if (tsig == S_HARD_IGN || tsig == action)
 		return 0;
 	switch (action) {
 		case S_DFL:	sigact = SIG_DFL;	break;
 		case S_CATCH:  	sigact = onsig;		break;
 		case S_IGN:	sigact = SIG_IGN;	break;
 	}
-	*t = action;
+	if (!vforked)
+		*t = action;
 	siginterrupt(signo, 1);
 	return (long)signal(signo, sigact);
 }
@@ -257,13 +266,15 @@ getsigaction(signo, sigact)
  */
 
 void
-ignoresig(signo)
+ignoresig(signo, vforked)
 	int signo;
+	int vforked;
 {
 	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
 		signal(signo, SIG_IGN);
 	}
-	sigmode[signo - 1] = S_HARD_IGN;
+	if (!vforked)
+		sigmode[signo - 1] = S_HARD_IGN;
 }
 
 
@@ -274,7 +285,7 @@ INCLUDE "trap.h"
 SHELLPROC {
 	char *sm;
 
-	clear_traps();
+	clear_traps(0);
 	for (sm = sigmode ; sm < sigmode + NSIG ; sm++) {
 		if (*sm == S_IGN)
 			*sm = S_HARD_IGN;
@@ -344,9 +355,9 @@ setinteractive(on)
 
 	if (on == is_interactive)
 		return;
-	setsignal(SIGINT);
-	setsignal(SIGQUIT);
-	setsignal(SIGTERM);
+	setsignal(SIGINT, 0);
+	setsignal(SIGQUIT, 0);
+	setsignal(SIGTERM, 0);
 	is_interactive = on;
 }
 
diff --git a/bin/sh/trap.h b/bin/sh/trap.h
index 6eff5c7d507a..4f82ed08b1e2 100644
--- a/bin/sh/trap.h
+++ b/bin/sh/trap.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: trap.h,v 1.12 1998/07/28 11:41:58 mycroft Exp $	*/
+/*	$NetBSD: trap.h,v 1.13 2000/05/13 20:50:15 elric Exp $	*/
 
 /*-
  * Copyright (c) 1991, 1993
@@ -41,9 +41,9 @@
 extern int pendingsigs;
 
 int trapcmd __P((int, char **));
-void clear_traps __P((void));
-long setsignal __P((int));
-void ignoresig __P((int));
+void clear_traps __P((int));
+long setsignal __P((int, int));
+void ignoresig __P((int, int));
 void onsig __P((int));
 void dotrap __P((void));
 void setinteractive __P((int));