BusyBox combines tiny versions of many common UNIX utilities into a
single small executable. It provides replacements for most of the
utilities you usually find in GNU fileutils, shellutils, etc. The
utilities in BusyBox generally have fewer options than their
full-featured GNU cousins; however, the options that are included
provide the expected functionality and behave very much like their GNU
counterparts. BusyBox provides a fairly complete environment for any
small or embedded system.

Website http://busybox.net/
OSS