How to check if a file exists from a test?

Did you know that you can check inside your Specman code if a particular file exists in your project?
Did you know that you can run a command inside your Specman test?

Here are two ways to go about it:
How to use an argument from the command line to open a file?

Specman code to open a file passed to the e program from the command line, and allowing for the possible use of a default file name,