Merge pull request #171 from wrapl/dev

Updates.

docs/index.rst

@@ -75,6 +75,7 @@ Rabs build scripts are written using `Minilang <https://minilang.readthedocs.io>
 
    /quickstart
    /tutorial
+   /usage
    /reference
 
 Indices and tables

docs/usage.rst

@@ -0,0 +1,33 @@
+Usage
+=====
+
+.. code-block:: console
+
+   $ rabs <options>
+
+where ``<options>`` is any combination of the following:
+
+:``-h``
+   Show help and exit.
+:``-V``
+   Show version and exit.
+:``-D``\ *NAME*\ ``=``\ *VALUE*
+   Add a define for *NAME* with value *VALUE*. The ``=``\ *VALUE* may be omitted in which case ``1`` is used.
+:``-c``
+   Show command lines as they as are executed.
+:``-s``
+   Show status updates as targets are built.
+:``-b``
+   Show a progress bar as targets are built.
+:``-E`` *FILENAME*
+   Capture ``stderr`` output from commands to *FILENAME*.
+:``-p`` *COUNT*
+   Execute up to *COUNT* commands in parallel.
+:``-F`` *FILENAME*
+   Use *FILENAME* instead of :file:`build.rabs` as the build file name.
+:``-G``
+   Generate a dependancy graph in :file:`dependencies.dot`.
+:``-i``
+   Run in interactive mode showing a console instead of building any targets.
+:``-d``
+   Show activity in each thread (for debugging slow builds).