From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH iproute] iptuntap: show processes using tuntap interface
Date: Thu, 25 Aug 2016 08:44:24 -0700
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To: Hannes Frederic Sowa <hannes@stressinduktion.org>
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On Wed, 24 Aug 2016 20:08:25 +0200
Hannes Frederic Sowa <hannes@stressinduktion.org> wrote:

> Show which processes are using which tun/tap devices, e.g.:
> 
> $ ip -d tuntap
> tun0: tun
> 	Attached to processes: vpnc(9531)
> vnet0: tap vnet_hdr
> 	Attached to processes: qemu-system-x86(10442)
> virbr0-nic: tap UNKNOWN_FLAGS:800
> 	Attached to processes:
> 
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

I think reading all of /proc like this will scale really badly on large systems.
Why reinvent lsof?