Re: "hostname" question during Debian installation
On Wed, Feb 15, 2012 at 2:12 AM, Bob Proulx <email@example.com> wrote:
> Martin T wrote:
>> thank you for replies! So am I correct, that hostname set during the
>> installation is:
>> 1) mapped to an address from 127.0.0.0/8 range in /etc/hosts file
> Specifically 127.0.1.1 so that it is always available and doesn't
> conflict or confuse with 127.0.0.1 localhost. The newer networking
> subsystem is event driven and supports hotplug devices. It may come
> and go. Having a local address 127.0.1.1 will always exist and will
> always map back to the hostname even if the main networking is
> It's different from traditional systems but it solves problems
> introduced by event driven hotpluggable network devices. It allows a
> system to always be able to contact itself and the reverse mapping of
> the IP address back to a name always maps back to itself.
> This is important on mobile devices which may be offline but is a
> consistent strategy and works well on non-mobile devices too.
"libnss-myhostname" provides the same functionality as adding the
"127.0.1.1" line in "/etc/hosts".
>> 2) written to /etc/mailname
> Yes. And also to /etc/postfix/main.cf if postfix is installed. Or to
> other places if other MTAs are installed.
When you use "dpkg-reconfigure exim4-config" or "dpkg-reconfigure
postfix", "/etc/mailname" is updated; in postfix's case because "my
origin" is set to it in "/etc/postfix/main.cf".
Mutt also uses it but it can be overridden by "~/.muttrc".
>> 3) written to "message of the day" file
> No. The /etc/motd doesn't include the hostname. You are thinking of
> /etc/issue but it also doesn't include the hostname either. It
> may include @char and \char sequences which substitute the dynamically
> hostname at runtime though.
"/etc/motd" is a symlink to "/var/run/motd", which is generated at
boot by "/etc/init.d/bootlogs" and contains the output "uname -snrvm",
so "/etc/motd" does contain a box's hostname.
>> 4) usually used in shell prompt(for example "\[\e]0;\u@\h:
Like "/etc/issue" (where the hostname's set by "/n"), the hostname in
the prompt's set
by "\h" so it's changed dynamically at boot.