Function start_daemon 

pub fn start_daemon(
    addr: SocketAddr,
    config: Config,
    out: &Output,
) -> Result<()>

Starts the server as a background daemon (Unix only).

Spawns the current executable as a detached child process with stdout/stderr redirected to a log file, then writes the PID.

Errors

The data directory, log file, PID file or child process cannot be made.