- add new applet rdev (Grant Erickson)

- fixes and shrink (me)

util-linux/Config.in

@@ -707,6 +707,12 @@ config RDATE
 	  the RFC868 protocol, which is built into the inetd daemon on most
 	  systems.
 
+config RDEV
+       bool "rdev"
+       default n
+       help
+	  Print the device node associated with the filesystem mounted at '/'.
+
 config READPROFILE
 	bool "readprofile"
 	default n

util-linux/Kbuild

@@ -26,6 +26,7 @@ lib-$(CONFIG_MORE)              += more.o
 lib-$(CONFIG_MOUNT)             += mount.o
 lib-$(CONFIG_PIVOT_ROOT)        += pivot_root.o
 lib-$(CONFIG_RDATE)             += rdate.o
+lib-$(CONFIG_RDEV)              += rdev.o
 lib-$(CONFIG_READPROFILE)       += readprofile.o
 lib-$(CONFIG_RTCWAKE)           += rtcwake.o
 lib-$(CONFIG_SCRIPT)            += script.o

util-linux/rdev.c

@@ -0,0 +1,24 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * rdev - print device node associated with a filesystem
+ *
+ * Copyright (c) 2008 Nuovation System Designs, LLC
+ *   Grant Erickson <gerickson@nuovations.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ *
+ */
+
+#include "libbb.h"
+
+int rdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int rdev_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
+{
+	char const * const root_device = find_block_device("/");
+
+	if (root_device != NULL) {
+		printf("%s /\n", root_device);
+		return EXIT_SUCCESS;
+	}
+	return EXIT_FAILURE;
+}