Index: head/tools/tools/decioctl/Makefile
===================================================================
--- head/tools/tools/decioctl/Makefile
+++ head/tools/tools/decioctl/Makefile
@@ -0,0 +1,10 @@
+# $FreeBSD$
+
+PROG=	decioctl
+SRCS=	decioctl.c
+MAN=
+BINDIR?= /usr/bin
+
+LIBADD=	sysdecode
+
+.include <bsd.prog.mk>
Index: head/tools/tools/decioctl/decioctl.c
===================================================================
--- head/tools/tools/decioctl/decioctl.c
+++ head/tools/tools/decioctl/decioctl.c
@@ -0,0 +1,94 @@
+/*-
+ * Copyright (c) 2005-2006,2016 John H. Baldwin <jhb@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/ioccom.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysdecode.h>
+
+static void
+usage(char **av)
+{
+	fprintf(stderr, "%s: <ioctl> [ ... ]\n", av[0]);
+	exit(1);
+}
+
+int
+main(int ac, char **av)
+{
+	unsigned long cmd;
+	const char *name;
+	char *cp;
+	int group, i;
+
+	if (ac < 2)
+		usage(av);
+	printf("  command :  dir  group num  len name\n");
+	for (i = 1; i < ac; i++) {
+		errno = 0;
+		cmd = strtoul(av[i], &cp, 0);
+		if (*cp != '\0' || errno != 0) {
+			fprintf(stderr, "Invalid integer: %s\n", av[i]);
+			usage(av);
+		}
+		printf("0x%08lx: ", cmd);
+		switch (cmd & IOC_DIRMASK) {
+		case IOC_VOID:
+			printf("VOID ");
+			break;
+		case IOC_OUT:
+			printf("OUT  ");
+			break;
+		case IOC_IN:
+			printf("IN   ");
+			break;
+		case IOC_INOUT:
+			printf("INOUT");
+			break;
+		default:
+			printf("%01lx ???", (cmd & IOC_DIRMASK) >> 29);
+			break;
+		}
+		printf(" ");
+		group = IOCGROUP(cmd);
+		if (isprint(group))
+			printf(" '%c' ", group);
+		else
+			printf(" 0x%02x", group);
+		printf(" %3lu %4lu", cmd & 0xff, IOCPARM_LEN(cmd));
+		name = sysdecode_ioctlname(cmd);
+		if (name != NULL)
+			printf(" %s", name);
+		printf("\n");
+	}
+	return (0);
+}