`?timeout:float ->
?env:string array ->
?stderr:Lwt_process.redirection ->
Lwt_process.command ->
object
method close : Unix.process_status Lwt.t
method kill : int -> unit
method pid : int
method rusage : Lwt_unix.resource_usage Lwt.t
method state : state
method status : Unix.process_status Lwt.t
method stdin : Lwt_io.output_channel
method stdout : Lwt_io.input_channel
method terminate : unit
end`