Date: Tue, 14 Mar 2006 09:59:40 -0800
From: Paul Jackson <pj@sgi.com>
To: "Paul Rolland" <rol@witbe.net>
Cc: hancockr@shaw.ca, kernel@wildsau.enemy.org, linux-kernel@vger.kernel.org
Subject: Re: procfs uglyness caused by "cat"
Message-Id: <20060314095940.7be639e7.pj@sgi.com>
In-Reply-To: <001901c6477c$a46b4c90$b600a8c0@cortex>
References: <4416D4A3.9070705@shaw.ca>
	<001901c6477c$a46b4c90$b600a8c0@cortex>
Organization: SGI
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 816
Lines: 28

Paul Rolland wrote:
> is funny enough...

You used the stdio routine fread - which buffers in user space.  It
does a single read, and then feeds you the characters as you ask for
them, out of its stdio buffer.

Try the following program, which doesn't buffer:

main()
{
    char c;
    int fd = open("/proc/uptime", 0);
    while (read(fd, &c, 1) == 1) {
        write(1, &c, 1);
        sleep(1);
    }
}

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/