Slightly OT: Error-Handling in a Pipeline, preferably non-zsh

[Aaron Davies <agdavi01@louisville.edu>]

How do I do return-value error handling in the middle of a pipeline? 
I'd ideally like to keep this to as basic a shell level as possible, 
plain (Bourne) sh-compatible if it can be done, though a bash or zsh 
solution will be fine if not. I'm tring to write a simple script that 
will apply a command to all processes matching a name--sort of a 
generalized "killall". At the moment, it looks like this:

#!/bin/sh

name=$1
shift

ps aux | grep $name | grep -v grep | grep -v $0 | awk '{ print $2 }' | 
xargs $@

and it works fine, and I'd like to keep it at that level of simplicity. 
The only thing is, I'd like to make it stop and return 1 if there are 
no matching processes. (At the moment, it calls the command with an 
empty argument list.) The intuitive thing to do seems to be

ps aux | grep $name | grep -v grep | ( grep -v $0 || exit 1 ) | awk '{ 
print $2 }' | xargs $@

but that doesn't work. Any ideas? (I could, of course, simply cache the 
last grep's results in a tmpfile, test its length, and proceed 
accordingly, but that doesn't seem quite as elegant.
-- 
Aaron Davies
agdavi01@louisville.edu