From v6.0 VMware vCenter Server Appliance supports 2 types shell, BASH shell and Appliance SHELL. To toggle between 2 different shells, do the following:
To run BASH shell, log in into your VCSA and type the following:
shell.set --enabled True shell
To tun Appliance shell, in your BASH shell type the following:
# chsh -s /bin/appliance root