[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: /lib/systemd/systemd-hostnamed hang

On Sat, Nov 24, 2012 at 6:27 PM, Zenaan Harkness <zen@freedbms.net> wrote:
> On 11/25/12, Michael Biebl <biebl@debian.org> wrote:
>> On 24.11.2012 14:40, Tom H wrote:
>>> On Sat, Nov 24, 2012 at 6:02 AM, Zenaan Harkness <zen@freedbms.net>
>>> wrote:
>>>> Any idea how to make use of systemd-hostnamed?
>>>> Eg:
>>>> $ sudo /lib/systemd/systemd-hostnamed
>>>> Warning: nss-myhostname is not installed. Changing the local hostname
>>>> might make it unresolveable. Please install nss-myhostname!
>>>> # hang's at this point, apparently indefinitely...
>>> What are you expecting it to do?
>> It doesn't hang. It is a system daemon which just waits sits there and
>> waits for requests (via D-Bus).
>> Nothing unexpected here aside from starting this tool directly.
>> It would be like starting apache by hand and then wondering that it sits
>> there waiting for requests via port 80.
> Thanks for the clarifications.
> $ lighttpd --help
> lighttpd: invalid option -- '-'
> lighttpd/1.4.31 (ssl) (Jul 14 2012 12:10:48) - a light and fast webserver
> usage:
>  -f <name>  filename of the config-file
>  -m <name>  module directory (default: /usr/lib/lighttpd)
>  -p         print the parsed config-file in internal form, and exit
>  -t         test the config-file, and exit
>  -D         don't go to background (default: go to background)
>  -v         show version
>  -V         show compile-time features
>  -h         show this help
> $ /lib/systemd/systemd-hostnamed --help
> This program takes no arguments.
> $ man lighttpd
> #...
> $ man systemd-hostnamed
> No manual entry for systemd-hostnamed
> I guess, being a "boot time" program and possibly headed for
> inclusion-in-initrd territory, the intent is to keep "core" daemons as
> small as possible, and not encumbered with memory consuming --help
> option?
> For discoverability/learnability of such things, should I be saying
> "the source code is the man page"?
> Or should I simply ignore all binaries in /lib/ ?
> >From /usr/share/doc/systemd/README, :
> "When systemd-hostnamed is used it is strongly recommended to
> install nss-myhostname to ensure that in a world of
> dynamically changing hostnames the hostname stays resolveable
> under all circumstances. In fact, systemd-hostnamed will warn
> if nss-myhostname is not installed. Packagers are encouraged to
> add a dependency on nss-myhostname to the package that
> includes systemd-hostnamed."
> Perhaps the lack of libnss causes the big delays when starting xterm
> after changing hostname?
> Ought there be an addition to man hostname, suggesting that updating
> hostname with /bin/hostname, and/ or with /etc/hostname edit, should
> be accompanied with an address resolvability update to /etc/hosts in
> order to avoid long timeouts when starting applications (perhaps just
> under X?) ??
> apropos hostname
> man 5 hostname
> # still no suggestion that changing hostname may cause resolver delays
> man 7 hostname
> # this possibly gives a bit of a hint
> (please note, I totally forgot about apropos until just now)
> What I am getting at here is the issue of (lack of) discoverability
> regarding this hostname-causing-application-startup-delays issue and
> how to fix it.
> debian-user is a great fallback. It ought to be possible, when someone
> in the future asks a similar question, that we can point the newbie to
> say
>   man hostname
>   # and read paragraph 3
> or say:
>   apropos hostname
>   man 5 hostname
>   # and read paragraph 3
> or some such.
> I attempted to discover/solve my problem/annoyance (10+ seconds xterm
> startup delays), but was not able to solve the problem with the
> references to the systems documentation which I tried, and I don't
> seem to see any clarity on this from man 5 or man 7 either.
> I am very grateful for the abundant documentation we have, and would
> like to see a little more, if that is a good idea in this case.
> A rough initial draft for an extra paragraph in man 1 hostname or man
> 5 hostname:
> WARNING (or CAUTION, or under NOTES ?)
>  Changing the hostname during runtime, without the new hostname being
>  resolvable to an ip address can cause delays when starting applications
>  which are in any way linked to the resolver(5).
>  This is the case for most(all?) X applications
> Suggestions appreciated, and when we have satisfactory wording, we can
> forward the suggestion to hostname-devel@lists.alioth.debian.org, and/
> or create a bug against hostname package? Guidance appreciated.

The latest version of system has hostnamectl and a man page for

Even if you weren't using systemd, you would've had the xterm problem
because you removed the standard " ..." line from
"/etc/hosts", although I'm not sure how xterm would behave with the
hostname known by the kernel being different from the one on the
"" line.

Anyway, AFAIU, systemd-hostnamed is there to provide an interface for
GUIs to change the hostname. At the CLI, "hostname <new-hostname>"
(and other changes should the new name have to be persistent) are
still the way to go - unless you have a version of systemd with

Reply to: