how to test if a pipe contains data

Laurent Bercot ska-dietlibc at skarnet.org
Mon Jan 23 23:36:53 UTC 2012


> I need to transfer data coming from a pipe over a UMTS link to a web server.
> From time to time, the UMTS link goes down, and worse, it sometimes cannot
> be reestablished. I believe that in these cases, the firmware of the UMTS stick
> hangs, but this is just a guess. Anyhow, the only way I could get the link up and
> running again when this happens is to reboot the whole system.
>
> As my application will have tried for quite a while to get the link up
> before such drastic measures, quite some data may have accumulated in the pipe.
> To avoid loosing that data, I need to drain the pipe to store its data
> to a file surviving the recovery. This is the place where I just want to check if
> there is still data in the pipe. If it is empty, I reboot.

 I must be missing something obvious here. Why don't you just do things
sequentially ?

 cat < namedpipe > savefile ; reboot

-- 
 Laurent


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