Linux: Which command shell am I using

To see which shell you are using you can enter a command like:

echo $SHELL

Or maybe go look in the user password file:

cat /etc/passwd

which may return:

/bin/bash 

 which will return a bunch of lines, along with one that is your username:

myusername:x:1000:1000:My,Name,999-999-9999,:/home/folder:/bin/bash

both of which tell me that I'm using the BASH shell.