BusyBox Default Function List

$ busybox

BusyBox v1.18.0 (2010-12-01 19:10:28 CET) multi-call binary.
Copyright (C) 1998-2009 Erik Andersen, Rob Landley, Denys Vlasenko
and others. Licensed under GPLv2.
See source distribution for full notice.

Usage: busybox [function] [arguments]...
   or: busybox --list[-full]
   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, add-shell, addgroup, adduser, adjtimex, ar, arp, arping,
 awk, base64, basename, bbconfig, beep, blkid, blockdev, bootchartd,
 brctl, bunzip2, bzcat, bzip2, cal, cat, catv, chat, chattr, chgrp,
 chmod, chown, chpasswd, chpst, chroot, chrt, chvt, cksum, clear, cmp,
 comm, conspy, cp, cpio, crond, crontab, cryptpw, cttyhack, cut, date,
 dc, dd, deallocvt, delgroup, deluser, depmod, devfsd, devmem, df,
 dhcprelay, diff, dirname, dmesg, dnsd, dnsdomainname, dos2unix, dpkg,
 dpkg-deb, du, dumpkmap, dumpleases, echo, ed, egrep, eject, env,
 envdir, envuidgid, ether-wake, expand, expr, fakeidentd, false, fbset,
 fbsplash, fdflush, fdformat, fdisk, fgconsole, fgrep, find, findfs,
 flash_eraseall, flash_lock, flash_unlock, flashcp, flock, fold, free,
 freeramdisk, fsck, fsck.minix, fsync, ftpd, ftpget, ftpput, fuser,
 getopt, getty, grep, gunzip, gzip, halt, hd, hdparm, head, hexdump,
 hostid, hostname, httpd, hush, hwclock, id, ifconfig, ifdown,
 ifenslave, ifplugd, ifup, inetd, init, inotifyd, insmod, install,
 ionice, iostat, ip, ipaddr, ipcalc, ipcrm, ipcs, iplink, iproute,
 iprule, iptunnel, kbd_mode, kill, killall, killall5, klogd, last,
 length, less, linux32, linux64, linuxrc, ln, loadfont, loadkmap,
 logger, login, logname, logread, losetup, lpd, lpq, lpr, ls, lsattr,
 lsmod, lspci, lsusb, lzcat, lzma, lzop, lzopcat, makedevs, makemime,
 man, md5sum, mdev, mesg, microcom, mkdir, mkdosfs, mke2fs, mkfifo,
 mkfs.ext2, mkfs.minix, mkfs.reiser, mkfs.vfat, mknod, mkpasswd, mkswap,
 mktemp, modinfo, modprobe, more, mount, mountpoint, mpstat, msh, mt,
 mv, nameif, nanddump, nandwrite, nbd-client, nc, netstat, nice, nmeter,
 nohup, nslookup, ntpd, od, openvt, passwd, patch, pgrep, pidof, ping,
 ping6, pipe_progress, pivot_root, pkill, pmap, popmaildir, poweroff,
 powertop, printenv, printf, ps, pscan, pwd, raidautorun, rdate, rdev,
 readahead, readlink, readprofile, realpath, reboot, reformime,
 remove-shell, renice, reset, resize, rev, rfkill, rm, rmdir, rmmod,
 route, rpm, rpm2cpio, rtcwake, run-parts, runlevel, runsv, runsvdir,
 rx, script, scriptreplay, sed, sendmail, seq, setarch, setconsole,
 setfont, setkeycodes, setlogcons, setsid, setuidgid, sh, sha1sum,
 sha256sum, sha512sum, showkey, slattach, sleep, smemcap, softlimit,
 sort, split, start-stop-daemon, stat, strings, stty, su, sulogin, sum,
 sv, svlogd, swapoff, swapon, switch_root, sync, sysctl, syslogd, tac,
 tail, tar, taskset, tcpsvd, tee, telnet, telnetd, test, tftp, tftpd,
 time, timeout, top, touch, tr, traceroute, traceroute6, true, tty,
 ttysize, tunctl, tune2fs, ubiattach, ubidetach, udhcpc, udhcpd, udpsvd,
 umount, uname, uncompress, unexpand, uniq, unix2dos, unlzma, unlzop,
 unxz, unzip, uptime, usleep, uudecode, uuencode, vconfig, vi, vlock,
 volname, wall, watch, watchdog, wc, wget, which, who, whoami, xargs,
 xz, xzcat, yes, zcat, zcip

click here for the command usage manual :)