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From: Paolo Bonzini <pbonzini@redhat.com>
Date: Sun, 15 Jan 2012 11:51:17 +0100
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Subject: Re: [Qemu-devel] qemu-nbd daemonizing?
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To: qemu-devel@nongnu.org

On 01/14/2012 10:26 AM, Michael Tokarev wrote:
> After looking at the yesterdays issue with non-absolute
> paths for qemu-nbd arguments and daemon(3), I've a
> question.
>
> Why qemu-nbd daemonizes, and does that only when device
> argument is given (dropping -v/verbose case for now)?
>
> This raises two questions:
>
>   - shouldn't it do the same daemonizing in case of usual
>     tcp export?

Perhaps yes, but in that case you cannot use "qemu-nbd -d" to kill the 
daemonized process.  Also, one of the best things of systemd is that it 
handles daemonization on its own, so nowadays it is better not to have 
process send themselves into background by default.

>   - shouldn't the daemonizing itself be controlled by an
>     option (like -d), and why we can't just send it to
>     background using "&" shell constuct?

Daemonization does more than "&" (the double fork+setsid process).

> And while at it, I wonder why it is really unix-only?
> There's nothing unix-specific in there exept two things:
> it is the device handling (/dev/nbdX) and all the hacks
> around this (including this daemonizing).  The rest should
> work on win32 just fine.

I think it's just historical.

Paolo