After applying shellshock fixes to your Linux system you most likely won't be able to run bitbake -c menuconfig, or bitbake -c devshell any longer. You probably will see bitbake completing with no errors but also nothing happening. See also https://bugzilla.yoctoproject.org/show_bug.cgi?id=6880.
As a workaround you may unset the functions xxx which appear you find defined with BASH_FUNC_xxx().
I.E. for all functions you get via "set | grep BASH_FUNC" run an unset.
In my case I have BASH_FUNC_module. After running "unset module" I can successfully run bitbake -c menuconfig linux-yocto again