I don't need to do anything fancy, I just need to know how to connect, from a command line, long enough to issue a sql command.

It's not hard to create and run a shell script in Linux distros like Ubuntu, but there are a few non-obvious pitfalls you need to avoid. Here's a quick example of how to execute a script in Linux.

If nano is your Linux editor of choice, and you want to make it a bit more flexible, Jack Wallen is ready to help you with the built-in Execute tool.