#!/bin/bash --posix
# OSX 10.7.5, default bash terminal.
# The _json_ version can be virtually anything but must NOT include '"' and ','...
# Obtain the relevant _text_ file.
# NOTE THAT THIS IS A HACK!
curl "https://s3.amazonaws.com/Minecraft.Download/versions/versions.json" > /tmp/jsonfile.dat
# Get the file into a variable...
text=$(cat < /tmp/jsonfile.dat)
# echo "$text"
# Ensure IFS is stored for future rplacement.
ifs_str="$IFS"
IFS=" "
# Use an array as a hack to get to the correct part...
array=($text)
# Check that the file contains the MCVERSION number with extras.
# This assumes that the file format remains the same upon every version.
version=$(echo "${array[5]}")
# echo "$version"
# You now have the version wrapped in inverted commas and a comma too...
# From here you can remove the '"' and ',' using builtins...
MCVERSION=""
decimal=0
subscript=0
length=$[ ${#version} - 1 ]
while [ $subscript -le $length ]
do
	# Remove the inverted commas...
	decimal=$(printf "%d" \'${version:$subscript:1})
	if [ $decimal -eq 44 ]
	then
		break
	fi
	if [ $decimal -eq 34 ]
	then
		subscript=$[ $subscript + 1 ]
	else
		MCVERSION=$MCVERSION${version:$subscript:1}
		subscript=$[ $subscript + 1 ]
	fi
done
# Print the final string...
echo "" 
echo "$MCVERSION"
echo ""
# Replace the original IFS...
IFS="$ifs_str"
# Get the length as a final check...
# length="${#MCVERSION}"
# echo "$length"

Last login: Fri Nov  1 19:03:30 on ttys000
AMIGA:barrywalker~> ./json.sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 15240  100 15240    0     0  13546      0  0:00:01  0:00:01 --:--:-- 15179

1.7.2

AMIGA:barrywalker~> _