Re: NetworkManager-list Digest, Vol 49, Issue 2

[Howard Chu <hyc symas com>]

Dan Williams wrote:
> On Wed, 2008-10-01 at 16:14 -0700, Howard Chu wrote:
> > > Message: 5
> > > Date: Wed, 1 Oct 2008 23:58:22 +0200
> > > From: Alexander Sack<asac jwsdot com>
> > > Subject: [PATCH] hostname support for ifupdown plugin + allow
> > > 	read-only	hostname system provider + move nm_inotify_helper to plugin
> > > 	independent place (system-settings/src/)
> > > To: networkmanager-list gnome org
> > > Message-ID:<20081001215822 GC26713 jwsdot com>
> > > Content-Type: text/plain; charset="us-ascii"
> > >
> > > Implement system hostname support for debian/ubuntu
> > >
> > > Fix "only system-setting plugins with NM_SYSTEM_CONFIG_INTERFACE_CAP_MODIFY_HOSTNAME
> > > are considered a valid hostname provider"
> > >
> > > Make nm-inotify-helper from ifcfg-fedora plugin usable
> > > for other plugins too
> > Is any of that really necessary? Any tool that rewrites /etc/hostname is also
> > going to already call sethostname(); shouldn't you only need to call
> > gethostname() to get NM in sync? Why go thru the hassle of opening and reading
> > a file and calling sethostname() to tell the kernel what it already knows?
>
> It's a matter of persistent storage... when you reboot you'd probably
> like to have the hostname come back as what you set it before, and that
> means you have to store the persistent hostname somewhere on the
> filesystem...

Right, and /etc/init.d takes care of reading it on boot, so NM doesn't need to 
worry about restoring the persisted state. Moreover, NM gets started too late 
in the boot process for it to be useful for this purpose.

> But it's just good programming to ensure that when that file changes,
> updates are recognized, because whatever wrote that file out doesn't
> _have_ to call sethostname(2).

Yes, but it's whatever wrote that file's responsibility to worry about it. 
After all, not everyone out there will even be running NetworkManager in the 
first place. Any admin tool that mucks around here can't assume that some 
other process will cleanup after it. Any sysadmin using vi has to know what 
they're doing.
--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/