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Date: Mon, 25 May 2009 14:36:03 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Ramagudi Naziir <naziirr@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: serial device and fsync
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On Mon, 25 May 2009 12:50:22 +0300
Ramagudi Naziir <naziirr@gmail.com> 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.