diff --git a/build.sh b/build.sh
index 45944e9..60c78ab 100755
--- a/build.sh
+++ b/build.sh
@@ -2,48 +2,9 @@
 # Copyright (c) 2016, 2017 Lucio Andrés Illanes Albornoz <lucio@lucioillanes.de>
 #
 
-#
-#
-#
-for __ in subr/*.subr; do . "${__}"; done;
-set -o noglob;
-while [ ${#} -gt 0 ]; do
-case ${1} in
--4)	ARG_IPV4_ONLY=1; ;;
--6)	ARG_IPV6_ONLY=1; ;;
--c)	ARG_CLEAN=1; ;;
--N)	ARG_OFFLINE=1; ;;
--i)	ARG_IGNORE_SHA256SUMS=1; ;;
--R)	ARG_RELAXED=1; ;;
---debug-minipix)
-	ARG_DEBUG_MINIPIX=1; ;;
--t*)	ARG_TARBALL=1; [ "${1#-t.}" != "${1}" ] && TARBALL_SUFFIX="${1#-t.}"; ;;
--v)	ARG_VERBOSE=1; ;;
--x)	ARG_XTRACE=1; set -o xtrace; ;;
--a)	[ -z "${2}" ] && exec cat etc/build.usage || ARCH="${2}"; shift; ;;
--b)	[ -z "${2}" ] && exec cat etc/build.usage || BUILD="${2}"; shift; ;;
--r)	if [ -z "${2}" ]; then
-		exec cat build.usage;
-	elif [ "${2%:*}" = "${2}" ]; then
-		ARG_RESTART="${2}";
-	else
-		ARG_RESTART="${2%:*}"; ARG_RESTART_AT="${2#*:}";
-	fi;
-	BUILD_PACKAGES_RESTART="$(echo ${ARG_RESTART} | sed "s/,/ /g")";
-	shift; ;;
-*=*)	set_var_unsafe "${1%%=*}" "${1#*=}"; ;;
-*)	if lmatch "${1}" " " "${ALL_TARGETS}"; then
-		BUILD_TARGETS_META="${BUILD_TARGETS_META:+${BUILD_TARGETS_META} }${1}";
-	else
-		exec cat etc/build.usage;
-	fi; ;;
-esac; shift; done;
-pre_setup_env; pre_check; pre_subdirs; build_files_init;
-
-#
-#
-#
-{(
+for __ in $(find subr -name *.subr); do . "${__}"; done;
+pre_setup_args "${@}"; pre_setup_env; pre_check; pre_subdirs;
+build_files_init; {(
 log_msg info "Build started by ${BUILD_USER:=${USER}}@${BUILD_HNAME:=$(hostname)} at ${BUILD_DATE_START}.";
 log_env_vars "build (global)" ${LOG_ENV_VARS};
 for BUILD_TARGET_LC in $(subst_tgts invariants ${BUILD_TARGETS_META:-world}); do
@@ -71,8 +32,7 @@ for BUILD_TARGET_LC in $(subst_tgts invariants ${BUILD_TARGETS_META:-world}); do
 	if [ "${BUILD_SCRIPT_RC:-0}" -ne 0 ]; then
 		break;
 	fi;
-done;
-build_files_fini;
+done; build_files_fini;
 log_msg info "${BUILD_NFINI} finished, ${BUILD_NSKIP} skipped, and ${BUILD_NFAIL} failed builds in ${BUILD_NBUILT} build script(s).";
 log_msg info "Build time: ${BUILD_TIMES_HOURS} hour(s), ${BUILD_TIMES_MINUTES} minute(s), and ${BUILD_TIMES_SECS} second(s).";
 if [ ${ARG_RELAXED:-0} -eq 1 ]\
@@ -80,10 +40,10 @@ if [ ${ARG_RELAXED:-0} -eq 1 ]\
 	log_msg info "Build script failure(s) in: ${BUILD_PKGS_FAILED}.";
 fi;
 exit "${BUILD_SCRIPT_RC:-0}")} 2>&1 | tee "${BUILD_LOG_FNAME}" & TEE_PID="${!}";
+
 trap "rm -f ${BUILD_STATUS_IN_PROGRESS_FNAME};	\
 	log_msg fail \"Build aborted.\";	\
 	echo kill ${TEE_PID};			\
-	kill ${TEE_PID}" HUP INT TERM USR1 USR2;
-wait;
+	kill ${TEE_PID}" HUP INT TERM USR1 USR2; wait;
 
 # vim:filetype=sh
diff --git a/subr/pre_setup_args.subr b/subr/pre_setup_args.subr
new file mode 100644
index 0000000..e9c10a5
--- /dev/null
+++ b/subr/pre_setup_args.subr
@@ -0,0 +1,67 @@
+BUILD_ARGS_SPEC="
+	ARG_IPV4_ONLY:-4
+	ARG_IPV6_ONLY:-6
+	ARCH:arg:-a
+	BUILD:arg:-b
+	ARG_CLEAN:-c
+	ARG_DEBUG_MINIPIX:--debug-minipix
+	ARG_IGNORE_SHA256SUMS:-i
+	ARG_OFFLINE:-N
+	ARG_RELAXED:-R
+	ARG_RESTART:arg:-r
+	ARG_TARBALL:selfarg:-t
+	ARG_TARBALL:selfarg:-t.bz2
+	ARG_TARBALL:selfarg:-t.gz
+	ARG_TARBALL:selfarg:-t.xz
+	ARG_VERBOSE:-v
+	ARG_XTRACE:-x";
+
+pre_setup_args() {
+	local _spec="${BUILD_ARGS_SPEC}" _spec_arg _found;
+	while [ ${#} -gt 0 ]; do
+		if [ "${1#-}" = "${1}" ]; then
+			break;
+		fi;
+		for _spec_arg in ${_spec}; do
+			case "${_spec_arg}" in
+			*:${1})	case "${_spec_arg#*:}" in
+				arg:*)
+					set_var_unsafe "${_spec_arg%%:*}" "${2}"; shift; ;;
+				selfarg:*)
+					set_var_unsafe "${_spec_arg%%:*}" "${1}"; ;;
+				*)
+					set_var_unsafe "${_spec_arg%%:*}" 1; ;;
+				esac; _found=1; break; ;;
+			*)	_found=0; ;;
+			esac;
+		done;
+		if [ "${_found:-0}" -eq 0 ]; then
+			exec cat etc/build.usage;
+		else
+			shift;
+		fi;
+	done;
+	if [ -n "${ARG_TARBALL}" ]; then
+		if [ "${ARG_TARBALL#-t.}" != "${ARG_TARBALL}" ]; then
+			TARBALL_SUFFIX="${ARG_TARBALL#-t.}";
+		else
+			TARBALL_SUFFIX=xz;
+		fi;
+	fi;
+	if [ "${ARG_XTRACE:-0}" -eq 1 ]; then
+		set -o xtrace;
+	fi;
+	if [ -n "${ARG_RESTART}" ]; then
+		if [ "${ARG_RESTART%:*}" != "${ARG_RESTART}" ]; then
+			ARG_RESTART_AT="${ARG_RESTART#*:}"; ARG_RESTART="${ARG_RESTART%:*}";
+		fi;
+		BUILD_PACKAGES_RESTART="$(echo ${ARG_RESTART} | sed "s/,/ /g")";
+	fi;
+	while [ ${#} -gt 0 ]; do
+	case "${1}" in
+	*=*)	set_var_unsafe "${1%%=*}" "${1#*=}"; ;;
+	*)	BUILD_TARGETS_META="${BUILD_TARGETS_META:+${BUILD_TARGETS_META} }${1}"; ;;
+	esac; shift; done;
+};
+
+# vim:filetype=sh
diff --git a/subr/pre_setup_env.subr b/subr/pre_setup_env.subr
index 0f22fdb..c1876d3 100644
--- a/subr/pre_setup_env.subr
+++ b/subr/pre_setup_env.subr
@@ -1,9 +1,6 @@
-#
-# set -o errexit -o noglob are assumed.
-#
-
 pre_setup_env() {
 	local __;
+	set -o noglob;
 	if [ -z "${DEFAULT_BUILD_CPUS}" ]\
 	&& [ -e /proc/cpuinfo ]; then
 		DEFAULT_BUILD_CPUS=$(awk '/^processor/{cpus++} END{print cpus}' /proc/cpuinfo);