I like this answer as a quick hack, but I got a lot of inconsistent results. I kept getting "event not found /io" when using zsh (I suppose it thinks ! is a history cmd), and "rchar: 4508" in bash for any ls I did, large or small, recursive or not. I got it to give me seemingly good values a few times, but I'd have to mess with it more to figure out why I had these problems.

I hate to do it, but I edited my question again to be i/o specific. I agree that it really depends on what kind of statistics you are trying to get at, and your answer gives me a very good idea of where I would want to go if I were needing to profile i/o for briefly running processes. By rewording my question back, I can give you the point for sharing an in-depth answer that seems instructive for similar cases.

Ok, thanks for helping me clarify what I'm wanting to know. I'm more interested in finding out how to get stats of any type for briefly running processes. I'm mainly wanting to know this to get performance stats, troubleshoot, and understand the system.

What if you have double quotes and single quotes in your command already? If it's not too far off-topic I'm sure others would want to know how...

I wish these questions (and answers) that deal with coreutils would routinely specify whether we're dealing with GNU or BSD (or other) utils.

Oh, nevermind about suppressing the error. I just redirect stderr to /dev/null before piping to grep and it works as I'd like.

Is there a way to suppress the error that comes from "if ls --version" when GNU coreutils aren't present (but still be able to test for coreutils)?

I've been playing around with different methods, and I think your "ugly" solution is pretty good and not even that ugly. As it turns out, I hadn't noticed the mismatch in options for ls earlier because I was using GNU coreutils from Ports. This is an example why doing an 'if' on $OSTYPE can fail to deliver desired results.