On Mon, 2014-11-03 at 13:03 +0100, Michael Biebl wrote: > Am 02.11.2014 um 03:06 schrieb Ben Hutchings: > > On Sun, 2014-11-02 at 02:34 +0100, Christian Hofstaedtler wrote: > >> * Ben Hutchings <[email protected]> [141101 14:02]: > >>> On Sat, 2014-11-01 at 13:22 +0100, Christian Hofstaedtler wrote: > > >> dash "backs up" any FDs it redirects, so it can restore them > >> later on. bash just closes them outright in this situation (forked > >> subshell + parent exits), causing udev's spawn_read to immediately, > >> thereby marking the udev event as finished. > > > > That makes *much* more sense. > > > [..] > > >> I'd suggest the following patch, as a stop gap for sysvinit users: > >> > >> Index: systemd-215/debian/extra/net.agent > >> =================================================================== > >> --- systemd-215.orig/debian/extra/net.agent 2014-09-27 > >> 17:50:52.000000000 +0200 > >> +++ systemd-215/debian/extra/net.agent 2014-11-02 02:33:40.970469131 +0100 > >> @@ -1,4 +1,4 @@ > >> -#!/bin/sh -e > >> +#!/bin/bash -e > > [..] > > > This seems to work under both bash and dash: > > > > exec > /dev/null 2> /dev/null > > do_everything & > > Thanks Ben and Christian for further debugging this. > I suspected the problem to be related to file descriptors when this > issue came up on debian-user [1] back in July. > > There I suggested to use > > ( do_everything ) > /dev/null 2> /dev/null & > > as a possible workaround. I don't particularly like using a subshell but > I'm just posting it for completeness sake here. > > I admit, I don't quite understand Ben's patch, which runs "exec" twice: > Once before do_everything() and later for the actual ifup/ifdown call. > What exactly does the first exec do to fix this?
The first exec does file redirection only, and this doesn't leave duplicate file descriptors. Ben. > Marco, do you have any preference? > > Michael > > [1] https://lists.debian.org/debian-user/2014/07/msg01509.html > -- Ben Hutchings Power corrupts. Absolute power is kind of neat. - John Lehman, Secretary of the US Navy 1981-1987
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