You will find lots of solutions for latest Ubuntu (14.xx) and for Ubuntu LTS versions like 10.04, 12.04, and 14.04, but for 12.10, a beautiful solution was provided by Digital Ocean Community. Special thanks to GD.
For easy reference, I copy-pasted the script lines below.
Run the below commands as root
[source]
mkdir src
cd src
wget http://ftp.gnu.org/gnu/bash/bash-4.3.tar.gz
#download all patches
for i in $(seq -f “%03g” 0 27); do wget http://ftp.gnu.org/gnu/bash/bash-4.3-patches/bash43-$i; done
tar zxvf bash-4.3.tar.gz
cd bash-4.3
#apply all patches
for i in $(seq -f “%03g” 0 27);do patch -p0 < ../bash43-$i; done
#build and install
./configure && make && make install
cd ..
cd ..
rm -r src
[/source]
The actual source is at Digital Ocean community
