43 lines
1.5 KiB
Markdown
43 lines
1.5 KiB
Markdown
---
|
|
title: "Open An IEx Shell From An Elixir Script"
|
|
blurb: "We can run an Elixir script with either the <code>elixir</code> or the <code>iex</code> command. Both will execute the code, but the second command opens an interactive IEx shell afterward. What if, we won't know until runtime whether we want a shell or not? How can we start an IEx session even when we use <code>elixir</code>, instead of <code>iex</code>, to run our script?"
|
|
...
|
|
|
|
{
|
|
id: "open-an-iex-shell-from-an-elixir-script"
|
|
}
|
|
|
|
## Method 1
|
|
|
|
Here's a quick test script:
|
|
|
|
<p class="code-filename-label">`run.exs`</p>
|
|
|
|
```elixir
|
|
:shell.start_interactive({IEx, :start, []})
|
|
|
|
System.no_halt(true)
|
|
```
|
|
|
|
`System.no_halt(true)` is needed so that the interactive session doesn't die when the process running the script ends. You could also use the `elixir` command with the `--no-halt` option instead to achieve the same effect.
|
|
|
|
When we run this script with just `elixir` (instead of `iex`), we should still see an interactive IEx session start.
|
|
|
|
```bash
|
|
$ elixir run.exs
|
|
Erlang/OTP 26 [erts-14.1] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit:ns]
|
|
|
|
Interactive Elixir (1.15.6) - press Ctrl+C to exit (type h() ENTER for help)
|
|
iex(1)>
|
|
```
|
|
|
|
## Method 2
|
|
|
|
While researching, I found another way that works, but it's even more obscure than the above method.
|
|
|
|
```elixir
|
|
:user_drv.start_shell(%{initial_shell: {IEx, :start, []}})
|
|
```
|
|
|
|
I can't find documentation for `user_drv`, I had to browse the [code](https://github.com/erlang/otp/blob/master/lib/kernel/src/user_drv.erl) directly.
|