diff --git a/spcd/bootstrap.sh b/spcd/bootstrap.sh
index 0e1ce38..137ac96 100644
--- a/spcd/bootstrap.sh
+++ b/spcd/bootstrap.sh
@@ -222,8 +222,9 @@ spcd_error_ci() {
 }
 
 spcd_error_os() {
+    spcd_error_os__variable="${1}"
     printf "× OS: "
-    spcd_os_printenv "${1}"
+    spcd_os_printenv "${spcd_error_os__variable}"
     exit "${_SPCD_ERROR_OS}"
 }
 
@@ -256,9 +257,10 @@ spcd_git_url() {
 # ╰───────────┴─────────╯
 
 spcd_openssl_x509() {
-    if [ -f "${1}" ]; then
+    spcd_openssl_x509__file="${1}"
+    if [ -f "${spcd_openssl_x509__file}" ]; then
         openssl x509 \
-            -in "${1}" \
+            -in "${spcd_openssl_x509__file}" \
             -noout -text
     fi
 }
@@ -276,16 +278,20 @@ spcd_os_grep() {
 }
 
 spcd_os_ls() {
-    if [ -n "${1}" ]; then
-        _spcd_frame_open "${1}"
-        ls -a -l "${1}"
-        _spcd_frame_shut "${1}"
+    spcd_os_ls__path="${1}"
+    if [ -n "${spcd_os_ls__path}" ]; then
+        _spcd_frame_open "${spcd_os_ls__path}"
+        ls -a -l "${spcd_os_ls__path}"
+        _spcd_frame_shut "${spcd_os_ls__path}"
     fi
 }
 
 spcd_os_mkdir() {
-    echo "→ ${1}"
-    mkdir --parents "${1}"
+    spcd_os_mkdir__path="${1}"
+    if [ -n "${spcd_os_mkdir__path}" ]; then
+        echo "→ ${spcd_os_mkdir__path}"
+        mkdir --parents "${spcd_os_mkdir__path}"
+    fi
 }
 
 spcd_os_printenv() {
@@ -329,6 +335,30 @@ spcd_os_write() {
     fi
 }
 
+# ╭───────────┬────────╮
+# │ functions │ python │
+# ╰───────────┴────────╯
+
+spcd_python_ln() {
+    spcd_python_ln__command="${1}"
+    if [ -n "${spcd_python_ln__command}" ]; then
+        echo "→ ${SPCD_PYTHON_ALIAS} → ${spcd_python_ln__command}"
+        ln -f -s "${spcd_python_ln__command}" \
+            "/usr/bin/${SPCD_PYTHON_ALIAS}"
+    fi
+}
+
+spcd_python_pip() {
+    if [ -n "${1}" ]; then
+        spcd_pp__name="$(basename "${1}")"
+        spcd_pp__path="$(spcd_git_clone "${1}")"
+        spcd_pp__path="${spcd_pp__path}/${spcd_pp__name}"
+        spcd_pp__target="${SPCD_PYTHON_VENV_PACKAGES}"
+        cp --recursive "${spcd_pp__path}" "${spcd_pp__target}"
+        echo "${spcd_pp__target}/${spcd_pp__name}"
+    fi
+}
+
 # ╭───────────┬───────╮
 # │ functions │ split │
 # ╰───────────┴───────╯
@@ -386,6 +416,9 @@ SPCD_PM_DNF="dnf"
 SPCD_PM_PACMAN="pacman"
 SPCD_PM_ZYPPER="zypper"
 
+SPCD_PYTHON_VENV="/opt/venv"
+SPCD_PYTHON_VENV_BINARIES="${SPCD_PYTHON_VENV}/bin"
+
 # ╭───────┬─────────────╮
 # │ steps │ environment │
 # ╰───────┴─────────────╯
@@ -481,6 +514,9 @@ ${SPCD_PROJECT_ROOT}$(basename "${GITHUB_SERVER_URL}")"
     #
     spcd_os_printenv "SPCD_PROJECT_BRANCH" \
         "SPCD_PROJECT_ROOT" "SPCD_PROJECT_PATH" "SPCD_PROJECT_NAME"
+    # set path
+    SPCD_PATH="$(realpath "${0}")"
+    spcd_os_printenv "SPCD_PATH"
     # set operating system id
     SPCD_OS_ID="$(spcd_os_grep ID)"
     case "${SPCD_OS_ID}" in
@@ -558,6 +594,11 @@ ${SPCD_PROJECT_ROOT}$(basename "${GITHUB_SERVER_URL}")"
     esac
     spcd_split
     spcd_os_printenv "SPCD_OS_ID" "SPCD_OS_VERSION"
+    # universal
+    SPCD_DNS_FILE="/etc/resolv.conf"
+    SPCD_PYTHON_ALIAS="python3"
+    spcd_split
+    spcd_os_printenv "SPCD_DNS_FILE" "SPCD_PYTHON_ALIAS"
     # set package manager
     case "${SPCD_OS_ID}" in
     "${SPCD_OS_ALPINE}")
@@ -577,9 +618,9 @@ ${SPCD_PROJECT_ROOT}$(basename "${GITHUB_SERVER_URL}")"
         ;;
     *) ;;
     esac
+    # set package manager variables
     spcd_split
     spcd_os_printenv "SPCD_PM"
-    # set package manager variables
     case "${SPCD_PM}" in
     "${SPCD_PM_DNF}")
         SPCD_PM_HTTPS_PATH="/etc/dnf/dnf.conf.d/https.conf"
@@ -678,10 +719,6 @@ Acquire::https::Verify-Peer False;
     esac
     spcd_split
     spcd_os_printenv "SPCD_URL_DEFAULT" "SPCD_URL_CHOSEN"
-    # set python alias
-    SPCD_PYTHON_ALIAS="python3"
-    spcd_split
-    spcd_os_printenv "SPCD_PYTHON_ALIAS"
     # set python command & package
     case "${SPCD_OS_ID}" in
     "${SPCD_OS_ALMA}" | "${SPCD_OS_ROCKY}")
@@ -751,9 +788,6 @@ Acquire::https::Verify-Peer False;
         ;;
     *) ;;
     esac
-    # set python virtual environment
-    SPCD_PYTHON_VENV="/opt/venv"
-    SPCD_PYTHON_VENV_BINARIES="${SPCD_PYTHON_VENV}/bin"
     SPCD_PYTHON_VENV_PACKAGES="\
 ${SPCD_PYTHON_VENV}/lib/${SPCD_PYTHON_COMMAND}/site-packages"
     spcd_split
@@ -797,26 +831,6 @@ spcd_install_package() {
     spcd_clean_cache
 }
 
-spcd_python_ln() {
-    spcd_python_ln__command="${1}"
-    if [ -n "${spcd_python_ln__command}" ]; then
-        echo "→ ${SPCD_PYTHON_ALIAS} → ${spcd_python_ln__command}"
-        ln -f -s "${spcd_python_ln__command}" \
-            "/usr/bin/${SPCD_PYTHON_ALIAS}"
-    fi
-}
-
-spcd_python_pip() {
-    if [ -n "${1}" ]; then
-        spcd_pp__name="$(basename "${1}")"
-        spcd_pp__path="$(spcd_git_clone "${1}")"
-        spcd_pp__path="${spcd_pp__path}/${spcd_pp__name}"
-        spcd_pp__target="${SPCD_PYTHON_VENV_PACKAGES}"
-        cp --recursive "${spcd_pp__path}" "${spcd_pp__target}"
-        echo "${spcd_pp__target}/${spcd_pp__name}"
-    fi
-}
-
 spcd_query_package() {
     case "${SPCD_PM}" in
     "${SPCD_PM_APK}") apk info "${1}" ;;
@@ -842,7 +856,7 @@ spcd_dns() {
 nameserver ${spcd_sdr__value}
 "
     done
-    spcd_os_write "/etc/resolv.conf" "${spcd_sdr__text}"
+    spcd_os_write "${SPCD_DNS_FILE}" "${spcd_sdr__text}"
 }
 
 # ╭───────┬──────────╮
@@ -1209,9 +1223,8 @@ SPCD_STEP = ${spcd_wpm__index}
 spcd_python_switch() {
     spcd_step "Switch"
     spcd_stp__name="$(basename "${SPCD_GIT_MAIN}")"
-    spcd_stp__path="$(realpath "${0}")"
     echo "\
-${spcd_stp__path}
+${SPCD_PATH}
 ↓
 ${SPCD_PYTHON_ALIAS} / ${spcd_stp__name}"
     "${SPCD_PYTHON_ALIAS}" -m "${spcd_stp__name}"