> Jacob is a Command line application framework with
> built-in support for shell autocompletion and help.
> It even has some UI tools.
>
> He's going to help you build self contained escript CLI's that can run on
> the BEAM.
## Hello world
Create a new module in your application and use `Jacob.Command` in it.
```elixir
defmodule Hello do
use Jacob.Command
@name "hello"
@desc "say hello"
def run(["hello", name]) do
IO.puts("hello #{name}")
end
end
```
build your escript with `mix escript.build`.
If your application is named `myapp` by default the escript filename will be `myapp`
so you should be able to run your new hello command like that:
```
./myapp hello world
```
> You can find more information about escripts with this command `mix help escript.build`
## Built-in commands
By default Jacob ships with two built-in commands.
#### help
The help command can be used to display a listing of all
the available commands in your application alongside their description.
#### shell:install-extension *<shell_name>*
where `shell_name` is either **bash** or **zsh**
This command can be used to install Jacob's shell extension which will
then enable tab completion on your application. For this extension to work
your application's escript file has to be in your system's PATH.
> Need more informations ?
> The doc is available on here: https://hexdocs.pm/jacob/
## Installation
To use Jacob in your project, first add Jacob as a dependency:
```elixir
def deps do
[
{:jacob, "~> 0.1.0"}
]
end
```
Then run `mix deps.get` and add Jacob's main module to your project's configuration.
```elixir
def project do
[
escript: [main_module: Jacob.Main]
]
end
```
## Configuration
Thereafter you'll have to set some configuration in your `config/config.exs` file.
The following are the defaults but you can ajust them as you like.
```elixir
config :jacob, :command_sources, [Mix.Project.config()[:app]]
config :jacob, :console_name, Mix.Project.config()[:app]
config :jacob, :console_version, Mix.Project.config()[:version]
config :jacob, :escript_name, Mix.Project.config()[:escript][:name] || Mix.Project.config()[:app]
```
### What's this and why do i need it ?
It appears that mix dependencies cannot access the root configuration of a mix project.
Therefore Jacob has to ask you for some of your project's information, that is:
* __:command_sources__
In which applications does Jacob have to look in order to find
your Jacob commands ?
This is usally the name of your application.
* __:console_name__
What's your console name ?
We'll default to the name of your application.
This information is will then be show by the help command.
* __:console_version__
What's your console version ?
We'll default to the version of your application.
This information is will then be show by the help command.
* __:escript_name__
What's the generated escript filename.
This option will not rename the generated escript file name,
but make Jacob aware of your escript filename.
