retroforth/book/Starting

# Starting RETRO

RETRO can be run for scripting or interactive use.

## Interactive

To start it interactively, run: `retro` without any command line
arguments, or with `-i`, `-s`, or `-c`.

Starting the interactive system:

```
retro
```

Or:

```
retro -i
```

This should be sufficient for most uses.

Starting the interactive system (without displaying the `Ok`
prompt or startup banner):

```
retro -s
```

RETRO also has a *character breaking* mode, in which input is
processed directly as entered, this is started with the `-c`
option:

```
retro -c
```

## Using In a Pipe

If using a Unix shell and piping input between processes, you
will probably want to use `-s` to supress the startup messages
and `Ok` prompt that normally appear.

E.g.,

```
echo "'lol s:put nl" | retro -s
```

## Running A Program In A File

You can run code in a file very easily. This is simply:

```
retro filename
```

You can follow the filename with any arguments that it may need.
These will be accessible to the program via the `sys:argc` and
`sys:argv` words.

Source files must be written in Unu format.

## Scripting

You can use RETRO to write scripts. Add a shebang:

```
#!/usr/bin/env retro
```

And make the file executable.

Source files must be written in Unu format.

## Command Line Arguments

For a summary of the full command line arguments available:

    Scripting Usage:

        retro filename [script arguments...]

    Interactive Usage:

        retro [-h] [-i] [-c] [-s] [-f filename] [-t]

      -h           Display this help text
      -i           Interactive mode (line buffered)
      -c           Interactive mode (character buffered)
      -s           Suppress the 'ok' prompt and keyboard
                   echo in interactive mode
      -f filename  Run the contents of the specified file
      -t           Run tests (in ``` blocks) in any loaded files