Information about which shell you are using is held in the SHELL environment variable. The command
echo $SHELL
displays the value of this variable.
You can identify which shell you are presently using from the last part of the pathname.
Pathname Shell
__________________________________________________________/.../sh Bourne shell /.../csh C shell /.../tcsh TC shell /.../ksh Korn shell /.../bash Bourne Again SHell __________________________________________________________