I agree, I discovered this function (pipes.quote) only through recommendation here:

http://stackoverflow.com/questions/4748344/whats-the-reverse-of-shlex-split

I suggest that it be added to shlex, perhaps as shlex.quote. While the quoting style it performs, and the module it's found in are specific to Unix tools, the shlex module is available on non-Unix platforms. To this end, adding the function to shlex would make it available elsewhere, as well as be appropriately shell-related.