Bug#867677: initramfs-tools: [patch] feature request: provide hook to set host name in InitRAMFS config dynamically

["M. Buecher" <maddes+debian@maddes.net>]

And if you remove the extension .sh, then it is also backwards 
compatible with Debian 4.0 "Etch" :)
# Define your network setup for the InitRAMFS via IP variable
#
# Still a kernel ip parameter will override any InitRAMFS config
# setting (see script /usr/share/initramfs-tools/init).
#
# Additional information:
# * https://www.kernel.org/doc/Documentation/filesystems/nfs/nfsroot.txt
#   In Debian as kernel command via /etc/default/grub
# * The "variable" ${hostname} (case-sensitive) will be replaced on InitRAMFS creation
#   with the current host name through the hook `set_hostname_in_network_config`
#   This allows the machine to be registered with its name in DNS.

IP=::::${hostname}

#!/bin/sh

#
# This InitRAMFS hook provides:
# Simple script to set IP parameter in InitRAMFS config with current
# hostname, instead of manually maintaining InitRAMFS config.

PREREQ=""

prereqs()
{
	echo "${PREREQ}"
}

case "${1}" in
 prereqs)
	prereqs
	exit 0
	;;
esac

. /usr/share/initramfs-tools/hook-functions

#
# Begin real processing
#
[ ! -f "${DESTDIR}/conf/initramfs.conf" ] || sed -i -e "s#\${hostname}#$(hostname)#" "${DESTDIR}/conf/initramfs.conf"
[ ! -f "${DESTDIR}/conf/conf.d/network" ] || sed -i -e "s#\${hostname}#$(hostname)#" "${DESTDIR}/conf/conf.d/network"