timebox.sh

#!/usr/bin/env bash

# Takes a 24-hour time as the first argument and displays the second argument as a Mac dialog at that time.
# Usage:
#   $ timebox 15:00 "Refresh the dashboard"

TARGET="${1}"
if [[ -z "${TARGET}" ]] ; then
  echo "You must pass a time as the first argument" >&2
  exit 1
fi

MSG="${2}"
if [[ -z "${MSG}" ]] ; then
  echo "You must pass message as the second argument" >&2
  exit 1
fi

current_epoch=$(gdate +%s)
target_epoch=$(gdate -d "today ${TARGET}" +%s)
sleep_seconds=$(( $target_epoch - $current_epoch ))

echo "Message will be displayed after ${sleep_seconds} seconds."

(
    sleep ${sleep_seconds};
    osascript -e "tell app \"System Events\" to display dialog \"$MSG\"" >/dev/null
) &