The .sh is for *nix systems and .bat should be for Windows. Since your example shows a bash error and you mention Terminal, I’m assuming it’s OS X you’re using.
In this case you should go to the folder and type:
./startup.sh
./ just means that you should call the script located in the current directory. (Alternatively, just type the full path of the startup.sh). If it doesn’t work then, check if startup.sh has execute permissions.