$ /bin/busybox
BusyBox v1.15.3 (2010-12-30 13:47:04 CST) multi-call binary
Copyright (C) 1998-2008 Erik Andersen, Rob Landley, Denys Vlasenko
and others. Licensed under GPLv2.
See source distribution for full notice.

Usage: busybox [function] [arguments]...
   or: function [arguments]...

	BusyBox is a multi-call binary that combines many common Unix
	utilities into a single executable.  Most people will create a
	link to busybox for each function they wish to use and BusyBox
	will act like whatever it was invoked as!

Currently defined functions:
	[, [[, acpid, addgroup, adduser, adjtimex, ar, arp, arping, ash, awk,
	basename, bb, bbconfig, bbsh, beep, blkid, brctl, bunzip2, bzcat,
	bzip2, cal, cat, catv, chat, chattr, chgrp, chmod, chown, chpasswd,
	chpst, chroot, chrt, chvt, cksum, clear, cmp, comm, cp, cpio, crond,
	cryptpw, cttyhack, cut, date, dd, deallocvt, delgroup, deluser, depmod,
	devmem, df, dhcprelay, diff, dirname, dmesg, dnsdomainname, dos2unix,
	dpkg-deb, du, dumpkmap, dumpleases, echo, ed, egrep, eject, env,
	envdir, envuidgid, ether-wake, expand, expr, false, fbset, fdflush,
	fdformat, fdisk, fgrep, find, findfs, flash_eraseall, flash_lock,
	flash_unlock, free, freeramdisk, fsck, fsck.minix, fsync, ftpd, fuser,
	getopt, getty, grep, gunzip, gzip, halt, hd, hdparm, head, hexdump,
	hostname, httpd, hwclock, id, ifconfig, ifdown, ifenslave, ifplugd,
	ifup, init, insmod, install, ionice, ip, ipaddr, ipcrm, ipcs, iplink,
	iproute, iprule, iptunnel, kbd_mode, kill, killall, killall5, klogd,
	last, length, less, linux32, linux64, linuxrc, ln, loadfont, loadkmap,
	logger, login, logread, losetup, lpq, lpr, ls, lsattr, lsmod, lzmacat,
	lzop, lzopcat, makedevs, makemime, man, md5sum, mdev, mesg, microcom,
	mkdir, mkdosfs, mkfifo, mkfs.minix, mkfs.vfat, mknod, mkpasswd, mkswap,
	mktemp, modprobe, more, mount, mountpoint, mt, mv, nameif, nc, netstat,
	nice, nmeter, nohup, nslookup, openvt, passwd, patch, pgrep, pidof,
	ping, ping6, pipe_progress, pivot_root, pkill, popmaildir, poweroff,
	printenv, printf, ps, pscan, pwd, raidautorun, rdate, rdev, readahead,
	readlink, readprofile, realpath, reboot, reformime, renice, reset,
	resize, rm, rmdir, rmmod, route, rtcwake, run-parts, runlevel, runsv,
	runsvdir, rx, script, scriptreplay, sed, sendmail, seq, setarch,
	setconsole, setfont, setkeycodes, setlogcons, setsid, setuidgid, sh,
	sha1sum, sha256sum, sha512sum, showkey, sleep, softlimit, sort, split,
	start-stop-daemon, stat, strings, stty, su, sum, sv, svlogd, swapoff,
	swapon, switch_root, sync, sysctl, syslogd, tac, tail, tar, tee,
	telnet, telnetd, test, tftp, tftpd, time, timeout, top, touch, tr,
	traceroute, true, tty, ttysize, tunctl, udhcpc, udhcpd, umount, uname,
	uncompress, unexpand, uniq, unix2dos, unlzma, unlzop, unzip, uptime,
	usleep, vconfig, vi, vlock, volname, watch, watchdog, wc, wget, which,
	who, whoami, xargs, yes, zcat, zcip

$ ls -l /bin/bb
lrwxrwxrwx 1 root root 7 Dec 30 13:48 /bin/bb -> busybox
$ ldd /bin/busybox
        not a dynamic executable
$ /bin/bb
~ # /bin/busybox touch file
~ # /bin/busybox ls -l file
-rw-r--r--    1 root     root            0 Dec 30 13:52 file
~ # /bin/busybox mv file file2
~ # /bin/busybox ls -l file2
-rw-r--r--    1 root     root            0 Dec 30 13:52 file2
~ #