systemd depends so heavily on a files it can not reboot

[John Reiser]

On 07/09/2013 01:22 AM, Gordon Messmer wrote:
> On 07/08/2013 09:39 AM, John Reiser wrote:
>> 1. Install a userid whose login shell is /usr/bin/sync
>>     (or a script which does "sync; sync")
>> 2. Login as the sync user (twice, perhaps.)
> 
> Running sync multiple times doesn't have any particular purpose on Linux.
> http://utcc.utoronto.ca/~cks/space/blog/unix/TheLegendOfSync

Yes it does, because the rest of the system might not be quiescent
during the first sync.  The first sync disturbs the system
with an impulse of activity.  This may cause the rest of
the processes to react in strange an wonderful ways, including
creating many changed-and-unwritten blocks.  The second sync
cleans many of these.  Of course this is a classic race condition
which might never get resolved, but the probabilities are
much more favorable after the second sync than after only
the first.