[ntp:questions] Handle ntp conf modification when ntp is already running

Terje Mathisen terje.mathisen at tmsw.no
Thu Apr 10 07:12:30 UTC 2014

Rob wrote:
> For Arthur: you need to modify the ntp.conf in case the system is
> rebooted outside your control (it will then use the values from ntp.conf)
> and at the same time use the above method to add the new server
> immediately.
> Then you do not need to restart ntpd and you can still change the config.

> OF COURSE ntpd should simply listen for SIGHUP and when it is received
> re-read the config file.  Like almost all Unix daemons do.

Here's the crux of the matter:

ntpd is _not_ a "Unix daemon", or at least not just that: The same code 
runs on many different operating systems, some of which don't implement 
SIGHUP at all, or at least not in a compatible manner.
> However, you will have a hard time convincing the group here, as you
> already found out.

I personally believe it would be nice if we did support SIGHUP on 
platforms where that is easily implementable, otoh ntpd is moving 
strongly towards a more or less auto-configurable setup:

A single 'pool pool.ntp.org' in the ntp.conf file (possibly added as 
default if started without a config file at all), and then the ntpd 
process will automatically redo the dns lookup every hour or so, pruning 
away the worst-performing servers and replacing them with new entries 
from the dns pool.


- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"

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