How can I kill a process when a specific string is seen on standard error?

Question

I need to start a process, lets say foo. I would like to see the stdout/stderr as normal, but grep the stderr for string bar. Once

Answer 1

Tom Anderson’s answer is quite good, but the kill $(cat $PIDFILE) will only happen on my system if foo terminated on its own, or through Ctrl-C. The following solution works for me

while read g
do
  if [[ $g =~ bar ]]
  then
    kill $!
  fi
done < <(
  exec foo 2> >(tee /dev/tty)
)