Re: serial device and fsync

From: Alan Cox
Date: Mon May 25 2009 - 09:35:12 EST

On Mon, 25 May 2009 12:50:22 +0300
Ramagudi Naziir <naziirr@xxxxxxxxx> wrote:

> Hi all,
> I need to write(2) a certain character to a serial device (using the
> standard /dev/ttySx), and make sure it was transferred to the device
> before I continue. I tried fsync(2), but that failed (does fsync even
> apply to character devices or only block devices ?).

Block devices
> Any idea ?

Most hardware UARTs actually can't do this but the kernel will do its
best. The POSIX interface you want is tcdrain(fd). Quite why POSIX didn't
use fsync is a very good question.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at