How do I execute a bash script in Terminal?

Yet another way to execute it (this time without setting execute permissions):

bash /path/to/scriptname

cd to the directory that contains the script, or put it in a bin folder that is in your $PATH

then type

./scriptname.sh

if in the same directory or

scriptname.sh

if it's in the bin folder.

$prompt: /path/to/script and hit enter. Note you need to make sure the script has execute permissions.