The Swiss Army Knife of Embedded Linux

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