Create minimal ubuntu installation from scratch

#!/bin/sh
#
# Create minimal ubuntu installation from scratch.
# Prerequisites: ubuntu precise installation, mounted empty fs at /target
#
debootstrap precise /target
cp /etc/resolv.conf /target/etc/resolv.conf
cp /etc/apt/sources.list /target/etc/apt/sources.list
mount --bind /dev /target/dev
cat > /target/chroot.sh  <<EOT
    #!/bin/sh
    mount none -t proc /proc
        mount none -t sysfs /sys
        mount none -t devpts /dev/pts
        export HOME=/root
        export LC_ALL=C
    echo "Please set passwords for root and ubuntu"
    echo "using the passwd command"
    bash -i
    apt-get update
    apt-get install --yes --force-yes linux-image-generic grub2 pump
    apt-get clean
        rm -rf /tmp/*
        rm /etc/resolv.conf
        umount -lf /proc
        umount -lf /sys
        umount -lf /dev/pts
EOT
chmod 755 /target/chroot.sh
chroot /target "/chroot.sh"
umount -lf /target/dev