`Exile.stream!/1` should be preferred over using this. Use this only if you need more control over the life-cycle of IO streams and OS process.
## Comparison with Port
* it is demand driven. User explicitly has to `read` the command output, and the progress of the external command is controlled using OS pipes. Exile never load more output than we can consume, so we should never experience memory issues
* it can close stdin while consuming output
* tries to handle zombie process by attempting to cleanup external process. Note that there is no middleware involved with exile so it is still possbile to endup with zombie process.
* selectively consume stdout and stderr streams
Internally Exile uses non-blocking asynchronous system calls to interact with the external process. It does not use port's message based communication, instead uses raw stdio and NIF. Uses asynchronous system calls for IO. Most of the system calls are non-blocking, so it should not block the beam schedulers. Make use of dirty-schedulers for IO
"""
use GenServer
alias __MODULE__
alias Exile.ProcessNif, as: Nif
require Logger
defstruct [
:args,
:errno,
:port,
:socket_path,
:stdin,
:stdout,
:stderr,
:status,
:use_stderr,
:await,
:read_stdout,
:read_stderr,
:read_any,
:write_stdin
]
defmodule Pending do
@moduledoc false
defstruct bin: [], size: 0, client_pid: nil
end
+ defmodule Error do
+ defexception [:message]
+ end
+
@default_opts [env: [], use_stderr: false]
@default_buffer_size 65535
@doc """
Starts `Exile.ProcessServer`
Starts external program using `cmd_with_args` with options `opts`
`cmd_with_args` must be a list containing command with arguments. example: `["cat", "file.txt"]`.
### Options
* `cd` - the directory to run the command in
* `env` - a list of tuples containing environment key-value. These can be accessed in the external program
* `use_stderr` - when set to true, exile connects stderr stream for the consumption. Defaults to false. Note that when set to true stderr must be consumed to avoid external program from blocking
"""
@type process :: pid
@spec start_link(nonempty_list(String.t()),
cd: String.t(),
env: [{String.t(), String.t()}],
use_stderr: boolean()
) :: {:ok, process} | {:error, any()}
def start_link(cmd_with_args, opts \\ []) do
opts = Keyword.merge(@default_opts, opts)
with {:ok, args} <- normalize_args(cmd_with_args, opts) do