#!/bin/sh
rootdev=unknown
while read fsdev fspath rest; do
	case "$fsdev" in
		/dev/root|rootfs)
			continue
			;;
	esac
	if [ "$fspath" = "/" ]; then
		rootdev="$fsdev"
	fi
done < /proc/self/mounts
if [ "$rootdev" != "unknown" ]; then
	echo "The root file system is on $rootdev"
else
	echo "/proc/mounts doesn't have an entry for the root file system!"
fi