I tried this and it didn't work on my Ubuntu machine, it echoed "stuff". env X="() { :;} ; echo busted" /bin/sh -c "echo stuff" But then I tried this command a

I tried this and it didn't work on my Ubuntu machine, it echoed "stuff". env X="() { :;} ; echo busted" /bin/sh -c "echo stuff" But then I tried this command and it echoed "vulnerable". env var='() { ignore this;}; echo vulnerable' bash -c /bin/true