Re: Problem with fdmove

From: Jan Olszak <jan.olszak_at_vestiacom.com>
Date: Mon, 15 Feb 2016 11:30:10 +0100

Thanks for reply!

I do have a notification-fd file:

# ls -hl
total 12K
-rw-rw-r-- 1 root root 415 Feb 14 20:04 README
drwx-ws--T 2 root root 40 Feb 15 10:25 event
drwxrwxr-x 5 root root 140 Feb 15 10:25 log
-rw-rw-r-- 1 root root 2 Feb 14 20:04 notification-fd
-rwxrwxr-x 1 root root 202 Feb 14 21:38 run
drwx------ 2 root root 100 Feb 15 10:25 supervise

Any other ideas?
When is notification-fd opened?

Cheers,
Jan



On Mon, Feb 15, 2016 at 11:20 AM, Laurent Bercot <ska-skaware_at_skarnet.org>
wrote:

> On 15/02/2016 10:55, Jan Olszak wrote:
>
>> The fdmove 1 3 operation shouts:
>> fdmove: fatal: unable to move fd 3 to fd 1: Bad file descriptor
>>
>
> That means fd 3 is not open. You need to have a notification-fd
> file that contains "3".
>
>
> If I comment this line out everything's OK. But I lose the notification
>> feature, that I'm not yet using.
>>
>
> Even if you're not using the notification feature, it doesn't hurt to
> specify a notification-fd for services that support it.
>
> Breaking down parts of the run script:
>
> "fdmove 1 3" says that everything that's written to stdout from now on
> will now be written to what was known as file descriptor 3. This means
> that fd 3 needs to be open for writing.
>
> The "-1" option to s6-ipcserver means that s6-ipcserver will write a
> newline to its stdout when it's ready. So it will notify readiness to
> the file descriptor that was known as 3 before running the script.
>
> So you need to have a proper notification-fd file containing 3. If
> you don't, fd 3 won't be open, and "fdmove 1 3" will fail.
>
> Don't worry about publishing readiness notifications even if nobody is
> listening. Publishing is a very light operation.
>
> --
> Laurent
>
>
Received on Mon Feb 15 2016 - 10:30:10 UTC