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Autore: Didier Kryn
Data:  
To: dng
Oggetto: Re: [Dng] printing (was Re: Readiness notification)
Le 14/06/2015 15:50, Laurent Bercot a écrit :
> On 14/06/2015 15:29, Nikolaus Klepp wrote:
>> And I thought the historic solution would be to give your web
>> printing service an id higher than cups, eg.:
>>
>> /etc/rc*/S04cups
>> /etc/rc*/S99awsomewebprinter
>>
>> Together with the nightmare from unix museum (aka fork when ready) it
>> simply works.
>
> No, it doesn't.
> The S04cups script will start cups, spawn the process, but exit
> before the
> service is ready; your sysv-rc mechanism will only see S04cups die, think
> it's okay, and start S99awsomewebprinter. There is a race condition and
> the web printing service may be started too early.


     Here comes the remark of Katolaz: "so what?".


     What happens then? Does the webprinting service crash? Or does it 
hang until Cups is ready? Is it able to detect that it is hanging? The 
last would probably be the most sensible way to handle the dependency 
:-) A professional webprinting service should be able to do that. And 
this is what Cups itself does when a printer is paused.


     Didier