The program will pause before and after commands are executed, press any key to continue.

* `LIBDEMO_INTERACTIVE`: enable (1, default) or disable (0) interactive mode. In non-interactive (automatic) mode, there is no waiting for input and some commands (prefixed with `i`) are skipped.

* `LIBDEMO_INTERACTIVE`: enable (1, default) or disable (0) interactive mode. In non-interactive (automatic) mode, pauses and `i` commands are skipped.

* `x` Execute arguments, expect success.
* `f` Execute arguments, expect failure.
* `i` Execute arguments in interactive mode only. Ignore exit status.

* `x` Print the provided arguments and execute them, expecting success. Pauses after the command is shown and after the command is run.
* `f` Print the provided arguments and execute them, expecting failure. Pauses after the command is shown and after the command is run.
* `i` Print the provided arguments and execute them in interactive mode only, ignoring exit status. Pauses after the command is shown and after the command is run.
* `p` Pause until any key is pressed.

Because of how the command evaluation is structured, care must be taken with characters that bash might interpret, in particular `'` and `|`, which may need escaping to `\'` and `\|` respectively.