Allow use of the ${MAKE_SHELL} variable to specify alternate shells for

make(1) to use.  Setting it to "sh" and "ksh" are the only values which
work right ATM; I wouldn't expect "csh" to get you far ;)

usr.bin/make/Makefile

@@ -12,4 +12,20 @@ SRCS+=	lstAppend.c lstAtEnd.c lstAtFront.c lstClose.c lstConcat.c \
 	lstMember.c lstNext.c lstOpen.c lstRemove.c lstReplace.c lstSucc.c
 .PATH:	${.CURDIR}/lst.lib
 
+# Set the shell which make(1) uses.  Bourne is the default, but a decent
+# Korn shell works fine, and much faster.  Using the C shell for this
+# will almost certainly break everything, but it's Unix tradition to
+# allow you to shoot yourself in the foot if you want to :-)
+
+MAKE_SHELL?=	sh
+.if ${MAKE_SHELL} == "csh"
+CFLAGS+=	-DDEFSHELL=0
+.elif ${MAKE_SHELL} == "sh"
+CFLAGS+=	-DDEFSHELL=1
+.elif ${MAKE_SHELL} == "ksh"
+CFLAGS+=	-DDEFSHELL=2
+.else
+.error "MAKE_SHELL must be set to one of \"csh\", \"sh\" or \"ksh\"."
+.endif
+
 .include <bsd.prog.mk>

usr.bin/make/config.h

@@ -39,8 +39,6 @@
  * $FreeBSD$
  */
 
-#define	DEFSHELL	1			/* Bourne shell */
-
 /*
  * DEFMAXJOBS
  * DEFMAXLOCAL

usr.bin/make/job.c

@@ -187,6 +187,16 @@ static Shell    shells[] = {
     FALSE, "echo \"%s\"\n", "sh -c '%s || exit 0'\n",
 #endif
     "v", "e",
+},
+    /*
+     * KSH description. The Korn shell has a superset of
+     * the Bourne shell's functionality.
+     */
+{
+    "ksh",
+    TRUE, "set -", "set -v", "set -", 5,
+    TRUE, "set -e", "set +e",
+    "v", "e",
 },
     /*
      * UNKNOWN.

usr.bin/make/main.c

@@ -478,6 +478,13 @@ main(argc, argv)
 					/* avoid faults on read-only strings */
 	static char syspath[] = _PATH_DEFSYSPATH;
 
+#if DEFSHELL == 2
+	/*
+	 * Turn off ENV to make ksh happier.
+	 */
+	unsetenv("ENV");
+#endif
+
 #ifdef RLIMIT_NOFILE
 	/*
 	 * get rid of resource limit on file descriptors
@@ -1000,7 +1007,13 @@ Cmd_Exec(cmd, err)
 	(void) dup2(fds[1], 1);
 	(void) close(fds[1]);
 
+#if DEFSHELL == 1
 	(void) execv("/bin/sh", args);
+#elif DEFSHELL == 2
+	(void) execv("/bin/ksh", args);
+#else
+#error "DEFSHELL must be 1 or 2."
+#endif
 	_exit(1);
 	/*NOTREACHED*/