HOSTNAME variable

[Thomas Neumann]

>> Find the row and add HOSTNAME=$host:
>> $append="append $initrd $bootprot $rootfs HOSTNAME=$host $opt_k $flags
>> $action\n";

> What does the nfsroot's `hostname` command report as the current hostname?

> Is it the same as the content of HOSTNAME or is it the original/unmodified
> host's name?

I just had a look at the relevant documentation / code for Debian.

$ man hostname
[...]
The host name is usually set once at system startup in
/etc/init.d/hostname.sh (normally by reading the contents of a file which
contains the
host name, e.g.  /etc/hostname).
[...]

$ cat /etc/init.d/hostname.sh
[...]
do_start () {
	[ -f /etc/hostname ] && HOSTNAME="$(cat /etc/hostname)"

	# Keep current name if /etc/hostname is missing.
	[ -z "$HOSTNAME" ] && HOSTNAME="$(hostname)"

	# And set it to 'localhost' if no setting was found
	[ -z "$HOSTNAME" ] && HOSTNAME=localhost

	[ "$VERBOSE" != no ] && log_action_begin_msg "Setting hostname to
'$HOSTNAME'"
	hostname "$HOSTNAME"
	ES=$?
	[ "$VERBOSE" != no ] && log_action_end_msg $ES
	exit $ES
}
[...]

So...

If there is a /etc/hostname the hostname will be set to its content.

If there is NO $HOSTNAME then the host's name will be set to whatever
`hostname` reports. (Most probably the value provided by DHCP.)

If HOSTNAME still does not contain anything, set it to 'localhost'.

undocumented/implicit cases:

If there is NO /etc/hostname AND $HOSTNAME contains something then the
host's name will be set to $HOSTNAME.

If there is a /etc/hostname AND $HOSTNAME contains something then
$HOSTNAME is ignored and /etc/hostname's content will be used.



[Maybe there's a modified /etc/init.d/hostname.sh / /etc/hostname in
Hiro's initrd, which sets the hostname to fai-live-host?]