This script works on Debian, (may need some tweak on Ubuntu)
#!/usr/bin/env bash
echo "Finding Debian/ Ubuntu Codename..."
CODENAME=`cat /etc/*-release | grep "VERSION=""VERSION="`
CODENAME=${CODENAME##*\(}
CODENAME=${CODENAME%%\)*}
echo "$CODENAME"
# => saucy, precise, lucid, wheezy, squeeze