docs I've read says echo $SHELL, while you remain in the system with the original login shell echo $SHELL gives the correct answer, but not in case you have executed another shell, for example: $ echo $SHELL /bin/bash $ csh % echo $SHELL /bin/bash % exit $ tcsh nahoo:~> echo $SHELL /bin/bash so, echo $SHELL seems not to be reliable, how could I now which shell I am using? (Imagine you need to know in a script)? Many thanks.