BusyBox for Windows is a portable toolkit which brings tiny versions of 117 Unix utilities into a single command line executable.
You don't need any Unix/ Linux knowledge to get at least something from the program, as some BusyBox commands are very simple. Cal displays a text calendar (month or year); df and du summarise hard drive use; hd displays the first 10 lines of a text file; sleep pauses your script for a defined time; unzip extracts files from archives, and so on.
If you're comfortable at the Windows command line then you'll appreciate BusyBox's more advanced tools. Diff compares text files and displays their differences; ftpput and ftpget store and retrieve files via ftp; grep is a powerful search tool with regular expression support; hexdump displays files in various custom formats; and there are smarter ways to copy files, compare them, and generally take better control of your system.
Linux experts should keep in mind that BusyBox has been optimised for size, and its tools generally don't have as many options as the originals. The program is more about convenience and portability than supporting every single optional switch.
For all that, there's plenty of power here, and BusyBox supports the following functions:
[, [[, ar, ash, awk, base64, basename, bash, bbconfig, bunzip2, bzcat, bzip2, cal, cat, catv, chmod, cksum, clear, cmp, comm, cp, cpio, cut, date, dc, dd, df, diff, dirname, dos2unix, du, echo, ed, egrep, env, expand, expr, false, fgrep, find, fold, ftpget, ftpput, getopt, grep, gunzip, gzip, hd, head, hexdump, kill, killall, ls, lzcat, lzma, lzop, lzopcat, man, md5sum, mkdir, mktemp, mv, od, patch, pgrep, pidof, printenv, printf, ps, pwd, rev, rm, rmdir, sed, seq, sh, sha1sum, sha256sum, sha3sum, sha512sum, shuf, sleep, sort, split, stat, strings, sum, tac, tail, tar, tee, test, touch, tr, true, uname, uncompress, unexpand, uniq, unix2dos, unlzma, unlzop, unxz, unzip, usleep, uudecode, uuencode, vi, wc, wget, which, whoami, xargs, xz, xzcat, yes and zcat.
Enter BusyBox at the command line to see this list, or add a function name - BusyBox grep - for help on what you can do.
There are more full-featured Windows versions of Unix tools around, but BusyBox provides a good basic selection in an extremely lightweight 645KB which runs on anything from XP up.