Currently defined functions:
 [, [[, ash, awk, basename, busybox, cat, chgrp, chmod, chown,
 chroot, chvt, clear, cmp, cp, cut, date, dd, df, dirname, dmesg,
 du, echo, egrep, env, expr, false, fgrep, find, free, fuser, getty,
 grep, gunzip, gzip, head, hostname, id, ifconfig, ifdown, ifup,
 insmod, kill, killall, last, ln, logger, login, ls, lsmod, mkdir,
 mkfifo, mknod, mkswap, mktemp, modprobe, more, mount, mv, netstat,
 nslookup, pivot_root, printf, ps, pwd, readlink, realpath, renice,
 reset, rm, rmdir, rmmod, route, run-parts, sed, seq, sh, sleep,
 sort, stty, su, swapoff, swapon, sync, sysctl, tail, tar, tee,
 test, time, top, touch, tr, true, tty, umount, uname, uniq, uptime,
 vi, wc, which, who, whoami, xargs, yes, zcat