Make the shell handle a null command in a &&/|| sequence correctly.

The && and || tokens do also terminate a command, not only the
newline.

While i was at it, disabled trace code by default, it served no good
purpose since it required the use of a debugger anyway to be turned
on.  Instead, placed a hint in the Makefile on how to turn it on.

This makes the shell ~ 10 % faster and ~ 4 KB smaller. :)

Pointed out by:  jan@physik.TU-Berlin.DE (Jan Riedinger)

bin/sh/Makefile

@@ -1,5 +1,5 @@
 #	@(#)Makefile	8.1 (Berkeley) 6/8/93
-#	$Id: Makefile,v 1.6 1994/09/24 02:57:18 davidg Exp $
+#	$Id: Makefile,v 1.7 1994/10/02 01:36:03 ache Exp $
 
 PROG=	sh
 SRCS=	alias.c builtins.c cd.c echo.c error.c eval.c exec.c expand.c \
@@ -11,6 +11,8 @@ DPADD=  ${LIBL} ${LIBEDIT} ${LIBTERMCAP}
 LDADD=  -ll -ledit -ltermcap
 LFLAGS= -8	# 8-bit lex scanner for arithmetic
 CFLAGS+=-DSHELL -I. -I${.CURDIR}
+# for debugging:
+#CFLAGS+=-g -DDEBUG=2
 .PATH:	${.CURDIR}/bltin ${.CURDIR}/../../usr.bin/printf
 CLEANFILES+=\
 	builtins.c builtins.h init.c mkinit mknodes mksignames mksyntax \

bin/sh/parser.c

@@ -33,7 +33,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: parser.c,v 1.6 1995/05/30 00:07:22 rgrimes Exp $
+ *	$Id: parser.c,v 1.7 1995/08/11 08:18:39 joerg Exp $
  */
 
 #ifndef lint
@@ -442,6 +442,8 @@ TRACE(("expecting DO got %s %s\n", tokname[got], got == TWORD ? wordtext : ""));
 		checkkwd = 1;
 		break;
 	/* Handle an empty command like other simple commands.  */
+	case TAND:
+	case TOR:
 	case TNL:
 	case TWORD:
 		tokpushback++;

bin/sh/shell.h

@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)shell.h	8.1 (Berkeley) 5/31/93
- *	$Id$
+ *	$Id: shell.h,v 1.2 1994/09/24 02:58:15 davidg Exp $
  */
 
 /*
@@ -57,7 +57,7 @@
 #ifndef BSD
 #define BSD 1
 #endif
-#define DEBUG 1
+/* #define DEBUG 1 */
 
 #ifdef __STDC__
 typedef void *pointer;