much better

core/printOwnDomain.sh

@@ -11,18 +11,21 @@ _CORE_SCRIPTS="$(dirname ${_SCRIPT:?"Missing SCRIPT"} 2> /dev/null)/"
 _CIS_ROOT="$(dirname ${_CORE_SCRIPTS:?"Missing CORE_SCRIPTS"} 2> /dev/null)/"
 _OVERRIDE_DOMAIN_FILE="${_CIS_ROOT:?"Missing CIS_ROOT"}overrideOwnDomain"
 
-# Wenn OVERRIDING_DOMAIN_FILE enhält lesbare Daten
-grep '[^[:space:]]' "${_OVERRIDE_DOMAIN_FILE:?"Missing OVERRIDE_DOMAIN_FILE"}" &> /dev/null \
-    && echo "WARNING: Domain has been overridden by: ${_OVERRIDE_DOMAIN_FILE}" > /dev/stderr \
-    && cat "${_OVERRIDE_DOMAIN_FILE}" \
-    && exit 0
-
-_BOOT_HOSTNAME="$(hostname -b)"
 # There has to be one dot at least.
-echo "${_BOOT_HOSTNAME}" | grep -v '\.' &> /dev/null \
+_BOOT_DOMAIN="$(hostname -b | grep -F '.' | cut -d. -f2-)"
-    && echo "It was impossible to find out the domain of this host, please prepare this host first." > /dev/stderr \
-    && exit 1
 
-#Removes shortest matching pattern '*.' from the begin to get the domain
+# Take OVERRIDING_DOMAIN_FILE without empty lines and comments, then take the first line without leading spaces
-echo "${_BOOT_HOSTNAME#*.}" \
+_OVERRIDE_DOMAIN="$(grep -vE '^[[:space:]]*$|^[[:space:]]*#' "${_OVERRIDE_DOMAIN_FILE}" 2> /dev/null | head -n 1 | xargs)"
+
+! [ -z "${_OVERRIDE_DOMAIN}" ] \
+    && [ "${_OVERRIDE_DOMAIN}" != "${_BOOT_DOMAIN}" ] \
+    && echo "WARNING: Domain has been overridden by: ${_OVERRIDE_DOMAIN_FILE}" > /dev/stderr \
+    && echo "${_OVERRIDE_DOMAIN}" \
     && exit 0
+
+! [ -z "${_BOOT_DOMAIN}" ] \
+    && echo "${_BOOT_DOMAIN}" \
+    && exit 0
+
+echo "It was impossible to find out the domain of this host, please prepare this host first." > /dev/stderr
+exit 1