Minecraft – I can’t destroy the bed in Minecraft 1.6.4

If you are using the latest vanilla launcher:

1. Create or edit a profile
2. Check the box labeled "Game Directory" and fill in a location to put it. It will automatically create the directory if it doesn't exist on next launch of the profile. (Note that I doubt it will expand shell variables, but it works just fine with symbolic links if you use those)
3. Click Save Profile

What I have done for this is I have created a directory under my $HOME called .minecraftProfiles and I put each separate profile in its own subdirectory. For example, vanilla 1.7.4 I have put at homedir/.minecraftProfiles/1.7.4-vanilla.

Sharing data between profiles:

• If and when I want to share a file and keep it shared (for better or for worse) I would symlink to it from one profile in the other(s).
• If I want to use some data (saves and such) as a basis for a new profile, I first copy the directory to a new one, create the new profile in the launcher (click "New Profile" when the one I'm copying is the selected profile), and after starting up that profile, (if necessary) do manual editing of the $HOME/.minecraft/versions/profilename/profilename.json when it is needed to have it actually keep some necessary data (if same version of Minecraft and wanting to keep Forge, for example)

Tips to avoid issues with losing valuable data:

• Keep multiple profiles in separate directories to avoid conflicting mods or mod configurations.
• Each profile should have a specific version set for the "Use version" under "Version Selection" in the Profile Editor to prevent it automatically updating and preventing you from playing on servers that haven't updated.
• Backup, backup, backup - before adding/removing mods, changing the version of a profile, and especially regular backups just in case your computer (or just Minecraft) crashes.

If you are not using the vanilla launcher (read: FTB / Technic launchers), all I can say with 100% reliability is you would have to either use a separate user account (for Linux, which you should be for different people anyways according to many Linux security specialists) or deal with moving the storage location of those launchers manually each time before starting.

(partially off topic) I choose to use a naming scheme of version-info for the naming of my profiles' directories, but you can opt for adding the user's name at the beginning of it.

The best way to try to figure out how this works is with some SCIENCE. To test this, I set my spawn in a bed in my test world. Then, I broke the bed, and placed it back in exactly the same position it was in when I set my spawn there (I used some wool to mark where the bed was and how it was oriented). When I used /kill, I respawned at the bed. However, if I break the bed, use /kill, and then replace it in the spot it was before, after having died, my spawn is no longer set.

The coordinates of the player's bed are stored in the Player.dat file. Upon respawning, the game checks to see if the bed is still there, and if there is a valid spawning space around it. If the bed is at those coordinates upon death, and there is a valid spawning space, the player will spawn there. Even if the bed had been broken. If the bed is missing or obstructed upon respawning, the bed coordinates are cleared.