diff --git a/Pmodules/libpbuild.bash b/Pmodules/libpbuild.bash
index 17c2de4..2943be8 100644
--- a/Pmodules/libpbuild.bash
+++ b/Pmodules/libpbuild.bash
@@ -71,10 +71,60 @@ declare PATCH_STRIPS=()
 declare PATCH_STRIP_DEFAULT='1'
 declare configure_with='undef'	
 
-#..............................................................................
-# global variables used in the library
+declare bootstrap='no'
 
-declare -r  OS="${SYSTEM}"
+#..............................................................................
+# global variables
+declare force_rebuild='no'
+pbuild.force_rebuild() {
+	force_rebuild="$1"
+}
+
+declare dry_run='no'
+pbuild.dry_run() {
+	dry_run="$1"
+}
+
+declare enable_cleanup_build='yes'
+pbuild.enable_cleanup_build() {
+	enable_cleanup_build="$1"
+}
+
+declare enable_cleanup_src='no'
+pbuild.enable_cleanup_src() {
+	enable_cleanup_src="$1"
+}
+
+declare build_target='all'
+pbuild.build_target() {
+	build_target="$1"
+}
+
+declare opt_update_modulefiles='no'
+pbuild.update_modulefiles() {
+	opt_update_modulefiles="$1"
+}
+
+# number of parallel make jobs
+declare -i  JOBS=3
+pbuild.jobs() {
+        JOBS="$1"
+}
+
+declare system=$(uname -s)
+pbuild.system() {
+        system="$1"
+}
+
+declare TEMP_DIR="${PMODULES_TMPDIR:-/var/tmp/${USER}}"
+pbuild.temp_dir() {
+        TEMP_DIR="$1"
+}
+
+declare PMODULES_DISTFILESDIR="${PMODULES_ROOT}/var/distfiles"
+pbuild.pmodules_distfilesdir() {
+        PMODULES_DISTFILESDIR="$1"
+}
 
 # module name including path in hierarchy and version
 # (ex: 'gcc/6.1.0/openmpi/1.10.2' for openmpi compiled with gcc 6.1.0)
@@ -83,13 +133,25 @@ declare -x  fully_qualified_module_name=''
 # group this module is in (ex: 'Programming')
 declare -x  GROUP=''
 
-# release of module (ex: 'stable')
+# name, version and release of module
+declare	-x  module_name=''
+declare	-x  module_version=''
 declare	-x  module_release=''
 
 # relative path of documentation
 # abs. path is "${PREFIX}/${_docdir}/${module_name}"
 declare -r  _DOCDIR='share/doc'
 
+# initialize module environment.
+# in case of bootstrapping the modulecmd does not exist. Setting
+# it to ':' is save. We check the existence later again.
+MODULECMD="${PMODULES_HOME}/bin/modulecmd"
+[[ -x ${MODULECMD} ]] || MODULECMD=':'
+
+eval $( "${MODULECMD}" bash use unstable )
+eval $( "${MODULECMD}" bash use deprecated )
+
+
 #..............................................................................
 #
 # The following variables are available in build-blocks and set read-only
@@ -99,6 +161,12 @@ declare -r  _DOCDIR='share/doc'
 # install prefix of module.
 declare -x  PREFIX=''
 
+# :FIXME:
+# OS is still used in some build-scripts. We have to implement a getter
+# and use this getter in the build-scripts.
+declare -r  OS="${system}"
+
+
 ##############################################################################
 #
 # Set flag to build module in source tree.
@@ -352,12 +420,12 @@ download_source_file() {
 pbuild::pre_prep() {
 	:
 }
-eval "pbuild::pre_prep_${SYSTEM}() { :; }"
+eval "pbuild::pre_prep_${system}() { :; }"
 
 pbuild::post_prep() {
 	:
 }
-eval "pbuild::post_prep_${SYSTEM}() { :; }"
+eval "pbuild::post_prep_${system}() { :; }"
 
 ###############################################################################
 #
@@ -392,6 +460,7 @@ pbuild::prep() {
                 std::die 3 \
                          "%s " "${module_name}/${module_version}:" \
                          "Download source not set!"
+        mkdir -p "${PMODULES_DISTFILESDIR}"
         local i=0
 	for ((i = 0; i < ${#SOURCE_URLS[@]}; i++)); do
 		download_source_file \
@@ -418,7 +487,7 @@ pbuild::add_patch() {
 	PATCH_FILES+=( "$1" )
 	PATCH_STRIPS+=( "$2" )
 }
-eval "pbuild::add_patch_${SYSTEM}() { pbuild::add_patch \"\$@\"; }"
+eval "pbuild::add_patch_${system}() { pbuild::add_patch \"\$@\"; }"
 
 pbuild::set_default_patch_strip() {
 	[[ -n "$1" ]] || \
@@ -439,7 +508,7 @@ pbuild::use_flag() {
 pbuild::pre_configure() {
 	:
 }
-eval "pbuild::pre_configure_${SYSTEM}() { :; }"
+eval "pbuild::pre_configure_${system}() { :; }"
 
 pbuild::set_configure_args() {
 	CONFIGURE_ARGS+=( "$@" )
@@ -501,12 +570,12 @@ pbuild::configure() {
 pbuild::post_configure() {
 	:
 }
-eval "pbuild::post_configure_${SYSTEM}() { :; }"
+eval "pbuild::post_configure_${system}() { :; }"
 
 pbuild::pre_compile() {
 	:
 }
-eval "pbuild::pre_compile_${SYSTEM}() { :; }"
+eval "pbuild::pre_compile_${system}() { :; }"
 
 pbuild::compile() {
 	make -j${JOBS}
@@ -515,12 +584,12 @@ pbuild::compile() {
 pbuild::post_compile() {
 	:
 }
-eval "pbuild::post_compile_${SYSTEM}() { :; }"
+eval "pbuild::post_compile_${system}() { :; }"
 
 pbuild::pre_install() {
 	:
 }
-eval "pbuild::pre_install_${SYSTEM}() { :; }"
+eval "pbuild::pre_install_${system}() { :; }"
 
 pbuild::install() {
 	make install
@@ -544,7 +613,7 @@ pbuild::install_shared_libs() {
 pbuild::post_install() {
 	:
 }
-eval "pbuild::post_install_${SYSTEM}() { :; }"
+eval "pbuild::post_install_${system}() { :; }"
 
 pbuild::cleanup_build() {
 	[[ "${BUILD_DIR}" == "${SRC_DIR}" ]] && return 0
@@ -616,11 +685,11 @@ pbuild::make_all() {
 	check_supported_systems() {
 		[[ -z "${SUPPORTED_SYSTEMS}" ]] && return 0
 		for sys in "${SUPPORTED_SYSTEMS[@]}"; do
-			[[ ${sys} == ${SYSTEM} ]] && return 0
+			[[ ${sys} == ${system} ]] && return 0
 		done
 		std::die 1 \
                          "%s " "${module_name}/${module_version}:" \
-                         "Not available for ${SYSTEM}."
+                         "Not available for ${system}."
 	}
 
 	#......................................................................
@@ -758,7 +827,7 @@ pbuild::make_all() {
                                          "since the dependency '$m' is ${release_of_dependency}"
                         # for a unstable module no dependency must be deprecated
                         elif [[ "${module_release}" == 'unstable' ]] \
-                                     && [[ "${release_of_dependency}" != 'deprecated' ]]; then
+                                     && [[ "${release_of_dependency}" == 'deprecated' ]]; then
                                 std::die 5 \
                                          "%s " "${module_name}/${module_version}:" \
                                          "release cannot be set to '${module_release}'" \
@@ -838,7 +907,7 @@ pbuild::make_all() {
 		post_install_linux() {
 			std::info \
                                 "%s " "${module_name}/${module_version}:" \
-                                "running post-installation for ${SYSTEM} ..."
+                                "running post-installation for ${system} ..."
 			cd "${PREFIX}"
 			# solve multilib problem with LIBRARY_PATH
                         # on 64bit Linux
@@ -847,7 +916,7 @@ pbuild::make_all() {
 		}
 
 		cd "${BUILD_DIR}"
-		[[ "${SYSTEM}" == "Linux" ]] && post_install_linux
+		[[ "${system}" == "Linux" ]] && post_install_linux
 		install_doc
 		install_pmodules_files
 		write_runtime_dependencies
@@ -898,7 +967,8 @@ pbuild::make_all() {
                         if [[ "${release}" != "${module_release}" ]]; then
 		                std::info \
                                         "%s " "${module_name}/${module_version}:" \
-                                        "changing release from '${release}' to '${module_release}' ..."
+                                        "changing release from" \
+                                        "'${release}' to '${module_release}' ..."
 		                echo "${module_release}" > "${release_file}"
                         fi
                 else
@@ -921,10 +991,10 @@ pbuild::make_all() {
 			# work because in some function global variables 
 			# might to be set.
 			#
-			cd "${dir}" && "pbuild::pre_${target}_${SYSTEM}"
+			cd "${dir}" && "pbuild::pre_${target}_${system}"
 			cd "${dir}" && "pbuild::pre_${target}"
 			cd "${dir}" && "pbuild::${target}"
-			cd "${dir}" && "pbuild::post_${target}_${SYSTEM}"
+			cd "${dir}" && "pbuild::post_${target}_${system}"
 			cd "${dir}" && "pbuild::post_${target}"
 			touch "${BUILD_DIR}/.${target}"
 		fi
@@ -1112,6 +1182,9 @@ pbuild.build_module() {
         shift 3
         with_modules=( "$@" )
 
+        [[ -x ${MODULECMD} ]] || \
+	        std::die 2 "No such file or executable -- '${MODULECMD}'"
+
         # P and V can be used in the build-script, so we have to set them here
         P="${module_name}"
         V="${module_version}"
@@ -1133,6 +1206,28 @@ pbuild.build_module() {
         std::info "%s" "${module_name}/${module_version}: Done ..."
 }
 
+pbuild.bootstrap() {
+	local -r name="$1"
+	local -r version="$2"
+
+	bootstrap='yes'
+
+	MODULECMD='/bin/true'
+	GROUP='Tools'
+	PREFIX="${PMODULES_ROOT}/${GROUP}/Pmodules/${PMODULES_VERSION}"
+
+	C_INCLUDE_PATH="${PREFIX}/include"
+	CPLUS_INCLUDE_PATH="${PREFIX}/include"
+	CPP_INCLUDE_PATH="${PREFIX}/include"
+	LIBRARY_PATH="${PREFIX}/lib"
+	LD_LIBRARY_PATH="${PREFIX}/lib"
+	DYLD_LIBRARY_PATH="${PREFIX}/lib"
+
+	PATH+=":${PREFIX}/bin"
+	PATH+=":${PREFIX}/sbin"
+	pbuild.build_module "${name}"  "${version}" 'stable'
+}
+
 # Local Variables:
 # mode: sh
 # sh-basic-offset: 8
diff --git a/Pmodules/modbuild b/Pmodules/modbuild
index f38f7bd..bdc2a12 100755
--- a/Pmodules/modbuild
+++ b/Pmodules/modbuild
@@ -1,5 +1,10 @@
 #!/bin/bash
-
+#
+# The following build specific variables are set and used in libpbuild.bash:
+#       ARGS
+#       BUILD_SCRIPT
+#       BUILDBLOCK_DIR
+#
 #.............................................................................
 # get absolute path of script
 declare	    mydir=$(dirname "$0")
@@ -12,28 +17,6 @@ PATH+=":${mydir}:${mydir}/../lib:${mydir}/../config"
 
 source libstd.bash    || { echo "Oops: library '$_' cannot be loaded!" 1>&2; exit 3; }
 
-#.............................................................................
-# constants
-declare	   fname_build_config='modbuild.conf'
-
-#.............................................................................
-# defaults for arguments/options
-
-# number of parallel make jobs
-declare -i  JOBS=3
-
-declare force_rebuild='no'
-declare dry_run='no'
-declare enable_cleanup_build='yes'
-declare enable_cleanup_src='no'
-declare build_target='all'
-declare bootstrap='no'
-declare SYSTEM="$(uname -s)"
-declare opt_update_modulefiles='no'
-
-# array collecting all modules specified on the command line via '--with=module'
-declare -a with_modules=()
-
 # save arguments, we might need them later again for building dependencies
 declare -r ARGS="$@"
 
@@ -127,18 +110,27 @@ MISCELLANEOUS OPTIONS:
 
 ##############################################################################
 #
+# parse options and arguments
+#
+
+# multiple version can be passed via comand line
+declare -a      versions=()
+declare         opt_all_variants='no'
+declare         opt_bootstrap='no'
+# array collecting all modules specified on the command line via '--with=module'
+declare -a      opt_with_modules=()
+declare 	build_config='modbuild.conf'
+declare         system="$(uname -s)"
 
-declare -a versions=()
-declare opt_all_variants='no'
 parse_args() {
 	while (( $# > 0 )); do
 		case $1 in
 		-j )
-			JOBS=$2
+			pbuild.jobs "$2"
 			shift
 			;;
 		--jobs=[0-9]* )
-			JOBS=${1/--jobs=}
+			pbuild.jobs "${1/--jobs=}"
 			;;
 		-v | --verbose )
 			trap 'echo "$BASH_COMMAND"' DEBUG
@@ -147,77 +139,79 @@ parse_args() {
 			set -x
 			;;
 		-f | --force-rebuild )
-			force_rebuild='yes'
+			pbuild.force_rebuild 'yes'
 			;;
 		-\? | -h | --help )
 			usage
 			;;
 		--dry-run )
-			dry_run='yes'
+			pbuild.dry_run 'yes'
 			;;
                 --all-variants )
                         opt_all_variants='yes'
                         ;;
 		--config )
-			fname_build_config="$2"
+			build_config="$2"
 			shift 1
 			;;
 		--config=* )
-			fname_build_config="${1#*=}"
+			build_config="${1#*=}"
 			;;
 		--disable-cleanup )
-			enable_cleanup_build='no'
-			enable_cleanup_src='no'
+			pbuild.enable_cleanup_build 'no'
+			pbuild.enable_cleanup_src 'no'
 			;;
 		--enable-cleanup-build )
-			enable_cleanup_build='yes'
+			pbuild.enable_cleanup_build 'yes'
 			;;
 		--disable-cleanup-build )
-			enable_cleanup_build='no'
+			pbuild.enable_cleanup_build 'no'
 			;;
 		--enable-cleanup-src )
-			enable_cleanup_src='yes'
+			pbuild.enable_cleanup_src 'yes'
 			;;
 		--disable-cleanup-src )
-			enable_cleanup_src='no'
+			pbuild.enable_cleanup_src 'no'
 			;;
 		--distdir )
-			PMODULES_DISTFILESDIR=$2
+			pbuild.pmodules_distfilesdir "$2"
 			shift
 			;;
 		--distdir=* )
-			PMODULES_DISTFILESDIR=${1/--distdir=}
+			pbuild.pmodules_distfilesdir "${1/--distdir=}"
 			;;
 		--tmpdir )
-			TEMP_DIR=$2
+			pbuild.temp_dir "$2"
 			shift
 			;;
 		--tmpdir=* )
-			TEMP_DIR=${1/--tmpdir=}
+			pbuilf.temp_dir "${1/--tmpdir=}"
 			;;
 		--system )
-			SYSTEM=".$2"
+			system=".$2"
+                        pbuild.system "${system}"
 			shift
 			;;
 		--system=* )
-			SYSTEM=".${1/*=}"
+			system=".${1/*=}"
+                        pbuild.system "${system}"
 			;;
 		--with )
-			with_modules+=( "$2" )
+			opt_with_modules+=( "$2" )
 			shift
 			;;
 		--with=*/* )
 			m="${1/--with=}"
-			with_modules+=( ${m} )
+			opt_with_modules+=( ${m} )
 			;;
 		--prep | --configure | --compile | --install | --all )
-			build_target=${1:2}
+			pbuild.build_target ${1:2}
 			;;
 		--bootstrap )
-			bootstrap='yes'
+			opt_bootstrap='yes'
 			;;
 		--update-modulefiles )
-			opt_update_modulefiles='yes'
+			pbuild.update_modulefiles 'yes'
 			;;
 		-* )
 			std::die 1 "Invalid option -- '$1'"
@@ -247,16 +241,16 @@ parse_args() {
 	(( ${#versions[@]} > 0)) || std::die 1 "Module version not specified!"
 }
 
-source libpbuild.bash || std::die 3 "Oops: library '$_' cannot be loaded!"
-
 find_variants_files(){
-	local files=( $(ls -1 "${BUILDBLOCK_DIR}"/*/variants.${SYSTEM} 2> /dev/null) )
+        shopt -q nullglob || :
+        local -i nullglob_set=$?
+        shopt -s nullglob
+	local files=( "${BUILDBLOCK_DIR}"/*/variants.${system} )
         local f
 	for f in "${BUILDBLOCK_DIR}"/*/variants; do
-		if [[ ! -e "${f}.${SYSTEM}" ]]; then
-			files+=( "$f" )
-		fi
+		[[ -e "${f}.${system}" ]] || files+=( "$f" )
 	done
+        (( nullglob_set == 1 )) && shopt -u nullglob
 	std::upvar "$1" "${files[@]}"
 }
 
@@ -279,9 +273,12 @@ build_modules() {
 	done
         local variants=()
         local variants_files=()
+        local line=''
         local lines=()
         for f in "${files[@]}"; do
-                mapfile -t lines < <(awk "${pattern}" "${f}")
+                while read line; do
+                        lines+=( "${line}" )
+                done < <(awk "${pattern}" "${f}")
                 variants+=( "${lines[@]}" )
                 local i
                 for ((i=0; i<${#lines[@]}; i++)); do
@@ -321,52 +318,33 @@ build_modules() {
 
 #.............................................................................
 # main
+source libpbuild.bash || std::die 3 "Oops: library '$_' cannot be loaded!"
+
 parse_args "$@"
 
 declare -r BUILD_SCRIPT
 declare -r BUILDBLOCK_DIR
 
-# source Pmodule environment configuration
-test -d ":${BUILDBLOCK_DIR}/../../${PMODULES_CONFIG_DIR}" && PATH+=":$_"
-test -d "${PMODULES_ROOT}/${PMODULES_CONFIG_DIR}" && PATH+=":$_"
-source "${fname_build_config}" || std::die 3 "Cannot source build configuration file."
-
-: ${TEMP_DIR:="${PMODULES_TMPDIR:-/var/tmp/${USER}}"}
-declare -rx  TEMP_DIR
-: ${PMODULES_DISTFILESDIR:="${BUILD_BASEDIR}/Downloads"}
-declare -xr  PMODULES_DISTFILESDIR
-mkdir -p "${PMODULES_DISTFILESDIR}"
-
-MODULECMD="${PMODULES_HOME}/bin/modulecmd"
-[[ -x ${MODULECMD} ]] || \
-	std::die 2 "No such file or executable -- '${MODULECMD}'"
-
 IFS=/ read -r -a fname <<< "${BUILD_SCRIPT:1}"
 module_name=${fname[${#fname[@]}-2]}
 
 #
-# are we bootstrapping? If yes, everything is a bit simpler...
+# are we bootstrapping? If yes, go for it...
 #
-if [[ "${bootstrap}" == 'yes' ]]; then
-	MODULECMD='/bin/true'
-        #......................................................................
-
-	C_INCLUDE_PATH="${PREFIX}/include"
-	CPLUS_INCLUDE_PATH="${PREFIX}/include"
-	CPP_INCLUDE_PATH="${PREFIX}/include"
-	LIBRARY_PATH="${PREFIX}/lib"
-	LD_LIBRARY_PATH="${PREFIX}/lib"
-	DYLD_LIBRARY_PATH="${PREFIX}/lib"
-
-	PATH+=":${PREFIX}/bin"
-	PATH+=":${PREFIX}/sbin"
-
-	pbuild.build_module "${module_name}"  "{versions[0]" 'stable'
+if [[ "${opt_bootstrap}" == 'yes' ]]; then
+        test -d ":${BUILDBLOCK_DIR}/../../${PMODULES_CONFIG_DIR}" && PATH+=":$_"
+        source "${build_config}" || std::die 3 "Cannot source build configuration file."
+	pbuild.bootstrap "${module_name}"  "${versions[0]}" 'stable'
         exit $?
 fi
 
-eval $( "${MODULECMD}" bash use unstable )
-eval $( "${MODULECMD}" bash use deprecated )
+#
+# we are NOT bootstrapping!
+#
+
+# source Pmodule environment configuration
+test -d "${PMODULES_ROOT}/${PMODULES_CONFIG_DIR}" && PATH+=":$_"
+source "${build_config}" || std::die 3 "Cannot source build configuration file."
 
 # if option '--all-variants' is set, we loop over all variants matching the given
 # versions
@@ -374,7 +352,7 @@ for version in "${versions[@]}"; do
         if [[ "${opt_all_variants}" == "no" ]]; then
                 version="=${version}"
         fi
-        build_modules "${module_name}" "${version}" "${with_modules[@]}"
+        build_modules "${module_name}" "${version}" "${opt_with_modules[@]}"
 done
 
 # Local Variables: