# set -x
 set -eu -o pipefail
 
 sock_dir="$(mktemp -d)"
 socket="${sock_dir}/it.sock"
 
 nix run . -- "$socket" echo it: 2>/dev/null &
 last="$!"
 
 cleanup() {
   rm -rf "$sock_dir"
   kill "$last"
 }
 trap "cleanup" EXIT INT HUP
 
 while ! [[ -S "$socket" ]]; do
   sleep 5
 done
 
 echo  first | socat - unix-connect:"$socket"
 echo second | socat - unix-connect:"$socket"
 echo  third | socat - unix-connect:"$socket"
 
 ## Expected Output
 
 # % ./test.zsh
 # ACK!
 # it: first
 # ACK!
 # it: second
 # ACK!
 # it: third