val blocking_waitpid : int -> (int * Unix.process_status) Lwt.t
type command_result = {
stdout: string;
stderr: string;
status: Unix.process_status;
}
val exec : string -> string list -> command_result Lwt.t
val exec_with_timeout :
timeout:float -> string -> string list -> (command_result, string) result Lwt.t