[philsnow]

that's way better than my alternative which was a bash function:

    function hl() {
      local R=''
      while [ $# -gt 0 ]; do
        R="$R|$1"
        shift
      done
      env GREP_COLORS="mt=38;5;$((RANDOM%256))" egrep --color=always $R
    }

thanks