# Unix Scripting

RETRO on Unix hosts is designed to play well with scripting.

Shebang

To run an entire program directly, start the file with the standard
shebang and make the file executable:

    #!/usr/bin/env retro

This requires the retro binary to be in your path.

## Arguments

RETRO provides several words in the `script:` namespace for accessing
command line arguments.

The number of arguments can be accessed via `script:arguments`. This
will return a number with the arguments, other than the script name.

    script:arguments '%n_arguments_passed\n s:format s:put

To retreive an argument, pass the argument number to `script:get-argument`:

    script:arguments [ I script:get-argument s:put nl ] indexed-times

And to get the name of the script, use `script:name`.

    script:name s:put

## Mixing

With use of the Unu literate format, it's possible to mix both shell
and RETRO code into a single script. As an example, this is a bit of
shell that runs itself via retro for each .retro file in the current
directory tree:

    #!/bin/sh

    # shell part
    find . -name '*.retro' -print0 | xargs -0 -n 1 retro $0
    exit

    # retro part

    This will scan a source file and do something with it:

    ~~~
    ... do stuff ...
    ~~~