freebsd/etc/rc.d/hostid_save

#!/bin/sh
#
# $FreeBSD$
#

# PROVIDE: hostid_save
# REQUIRE: root
# KEYWORD: nojail

. /etc/rc.subr

name="hostid_save"
start_cmd="hostid_save"
stop_cmd=":"
rcvar="hostid_enable"

hostid_save()
{
	current_hostid=`$SYSCTL_N kern.hostuuid`

	if [ -r ${hostid_file} ]; then
		read saved_hostid < ${hostid_file}
		if [ ${saved_hostid} = ${current_hostid} ]; then
			exit 0
		fi
	fi

	echo ${current_hostid} > ${hostid_file}
	if [ $? -ne 0 ]; then
		warn "could not store hostuuid in ${hostid_file}."
	fi
}

load_rc_config $name
run_rc_command "$1"