# `GeoGenius.Command`
[🔗](https://github.com/agoodway/geo_genius/blob/main/lib/geo_genius/command.ex#L1)

Behaviour for invoking an external executable.

The shapefile provider shells out to `ogr2ogr` to convert a source file to
the format GeoGenius ingests. `available?/2` lets a phase check for that
binary up front rather than discovering its absence mid-run, and `run/3`
invokes it and reports success or failure without raising: a missing
executable, a non-zero exit, and a zero exit all come back as plain return
values so a pipeline phase can handle every one of them the same way.

# `available?`

```elixir
@callback available?(executable :: String.t(), opts :: keyword()) :: boolean()
```

Reports whether `executable` can be found on the host's search path.

Takes the same `opts` as `run/3`, so an adapter that wraps or redirects
another one -- `GeoGenius.Pipeline.CommandAllowlist` does both -- answers a
probe about the same executable `run/3` would actually invoke, rather than
about whatever a second resolution path happens to find.

# `run`

```elixir
@callback run(executable :: String.t(), args :: [String.t()], opts :: keyword()) ::
  {:ok, output :: String.t()}
  | {:error, {exit_status :: integer(), output :: String.t()}}
```

Runs `executable` with `args` and returns its combined output.

Returns `{:ok, output}` for a zero exit, or `{:error, {exit_status, output}}`
otherwise. `output` interleaves stdout and stderr in the order the process
produced them. `opts` carries adapter-specific options such as `:cd` for the
working directory.

---

*Consult [api-reference.md](api-reference.md) for complete listing*