In light of UUID conversion, pull player names out of the NBT files.

spot.sh

#! /bin/sh
# Generate a markers.js file with markers for players based on their last-known positions.
# Requires a binary of NBTologist:
# https://gist.github.com/MrDOS/7836657

# Path to NBTologist.
NBTOLOGIST=/home/minecraft/map/nbtologist
# Path to directory containing player NBT files.
PLAYERS=/home/seecraft/map/world/playerdata
# The name of the Mapcrafter world.
WORLD=world
# Output markers.js file.
MARKERS=/home/minecraft/public_html/markers.js

cat <<EOF > "$MARKERS"
var MAPCRAFTER_MARKERS = [
    {
        "id": "players",
        "name": "Players",
        "showDefault": true,
        "markers": {
            "$WORLD": [
EOF

for player_file in "$PLAYERS"/*.dat
do
    player=`gunzip -c "$player_file" | "$NBTOLOGIST"`
    x=`echo "$player" | cut -d ' ' -f 1`
    y=`echo "$player" | cut -d ' ' -f 2`
    z=`echo "$player" | cut -d ' ' -f 3`
    player_name=`echo "$player" | cut -d ' ' -f 4`

    if [ -z "$player_name" ]
    then
        # No Bukkit "lastKnownName" tag -- we'll have to ask the session server.
        bare_uuid=`echo "$player_file" | sed -e 's/.*\/\(.*\).dat/\1/' | sed -e 's/-//g'`
        player_name=`curl -s https://sessionserver.mojang.com/session/minecraft/profile/"$bare_uuid" \
            | grep -oP '.*\[' | grep -oP -m 1 '"name":".+?"' \
            | sed -e 's/"name":"\(.*\)"/\1/'`
    fi

    echo "                {\"pos\": [$x, $z, $y], \"title\": \"$player_name\", \"icon\": \"http://overviewer.org/avatar/$player_name\", \"iconSize\": [16, 32]}," >> "$MARKERS"
done

cat <<EOF >> "$MARKERS"
            ]
        }
    }
];
EOF