However, withdrawal from caffeine is seldom dangerous, though it can make one uncomfortable for a few days. The most frequent symptom associated with this withdrawal is a moderate to severe headache. This can occur between 12 and 24 hours after last intake of caffeine.
Okay, for step one you need to get the command blocks in your inventory. Make sure you have cheats ON and say /give (player name) command_block. After you get in in your inventory place 5 in a row.
Command blocks can also be used to make a security system. Just put a pressure plate which triggers a command block in front of an iron door, which will be the entrance to your house. Insert the command: . For mobs, a simple fence or lava moat will do.