luke@samsung:~$ env X="() { :;} ; echo busted" /bin/sh -c "echo completed"
completed
luke@samsung:~$ env X="() { :;} ; echo busted" `which bash` -c "echo completed"
busted
completed
luke@samsung:~$ sudo apt-get update && sudo apt-get upgrade -y
...
...
...
luke@samsung:~$ env X="() { :;} ; echo busted" /bin/sh -c "echo completed"
completed
luke@samsung:~$ env X="() { :;} ; echo busted" `which bash` -c "echo completed"
/bin/bash: warning: X: ignoring function definition attempt
/bin/bash: error importing function definition for `X'
completed