First of all create the chroot using debootstrap:
BASECHROOT='/tmp/basefile'
- debootstrap squeeze "$BASECHROOT" http://cdn.debian.net/debian
+ debootstrap wheezy "$BASECHROOT" http://http.debian.net/debian
tar -C "$BASECHROOT" --exclude='var/cache/apt/archives/*.deb' -zcf base.tar.gz ./
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