---
title: Module commander
description: library for custom commands
layout: doc
menu:
  docs:
    parent: "API"
---

## Introduction

Commander is a library for writing custom commands in Lua.
In order to make it easier to write commands for Hilbish,
not require separate scripts and to be able to use in a config,
the Commander library exists. This is like a very simple wrapper
that works with Hilbish for writing commands. Example:

```lua
local commander = require 'commander'

commander.register('hello', function(args, sinks)
	sinks.out:writeln 'Hello world!'
end)
```

In this example, a command with the name of `hello` is created
that will print `Hello world!` to output. One question you may
have is: What is the `sinks` parameter?

A sink is a writable/readable pipe, or you can imagine a Lua
file. It's used in this case to write to the proper output,
incase a user either pipes to another command or redirects somewhere else.

So, the `sinks` parameter is a table containing 3 sinks:
`in`, `out`, and `err`.
- `in` is the standard input. You can read from this sink
to get user input. (**This is currently unimplemented.**)
- `out` is standard output. This is usually where text meant for
output should go.
- `err` is standard error. This sink is for writing errors, as the
name would suggest.

A sink has 2 methods:
- `write(str)` will write to the sink.
- `writeln(str)` will write to the sink with a newline at the end.

## Functions
### deregister(name)
Deregisters any command registered with `name`

### register(name, cb)
Register a command with `name` that runs `cb` when ran