watch, but it sprawls changes as a scrolling log.

.bash_aliases

watchh() {
  local cmd="$*"
  case "$1" in
    --no-hms)
      shift
      cmd="bash -c '$*' | sed -E 's/[0-2][0-9]:[0-5][0-9]:[0-5][0-9]/[no-hms]/g'"
      1>&2 echo "No HMS: $*"
      1>&2 echo "Becomes: $cmd"
    ;;
  esac
  local a=$(mktemp -t watchh_a.XXXXXX)
  local b=$(mktemp -t watchh_b.XXXXXX)
  trap 'rm -f "$a" "$b"' EXIT INT TERM
  echo > "$b"
  while true; do
    eval "$cmd" > "$a" 2>&1
    diff -wu1 --label "" --label "" "$b" "$a" && printf "\r$(date)\r" || date
    cat "$a" > "$b"
    sleep 1
  done
}