env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
cd /tmp; env X='() { (a)=>\' bash -c "echo date"; cat echo
cd ~/
mkdir bash
cd bash
wget https://ftp.gnu.org/gnu/bash/bash-4.2.tar.gz
for i in $(seq -f "%03g" 0 49); do wget https://ftp.gnu.org/gnu/bash/bash-4.2-patches/bash42-$i; done
tar zxvf bash-4.2.tar.gz
cd bash-4.2
for i in $(seq -f "%03g" 0 49); do patch -p0 < ../bash42-$i; done
./configure && make
sudo make install