Explanation of bash -ex

Bash scripts can use various options on the shebang (#!/bin/bash). A more common one is: ‘#!/bin/bash -ex’.
 
-e Exit immediately if a command exits with a non-zero status. -x Print commands and their arguments as they are executed.
 
In short, adding -ex to your #!/bin/bash will give verbose output and also will abort your script immediately if part of the script fails.