diff --git a/cd.sh b/cd.sh
index 5058593..eddae10 100644
--- a/cd.sh
+++ b/cd.sh
@@ -1,11 +1,11 @@
 #! /usr/bin/env sh
 
 # defaults
-[ "${CD_DNS}" ] || CD_DNS="\
+[ -n "${CD_DNS}" ] || CD_DNS="\
 9.9.9.9 \
 "
-[ "${CD_GIT_CHILD}" ] || CD_GIT_CHILD="cd"
-[ "${CD_GIT_PARENT}" ] || CD_GIT_PARENT="rwx"
+[ -n "${CD_GIT_CHILD}" ] || CD_GIT_CHILD="cd"
+[ -n "${CD_GIT_PARENT}" ] || CD_GIT_PARENT="rwx"
 
 # main
 cd_main () {
@@ -40,6 +40,9 @@ cd_main () {
 
 cd_set_environment_variables () {
     cd_step "Set environment variables"
+    # set path
+    CD_PATH="$(realpath "${0}")"
+    cd_echo "CD_PATH"
     # set operating system id
     CD_OS_ID="$(cd_grep_os ID)"
     case "${CD_OS_ID}" in
@@ -65,6 +68,7 @@ cd_set_environment_variables () {
         "${CD_OS_DEBIAN}"|"${CD_OS_UBUNTU}")
             CD_OS_VERSION="$(cd_grep_os VERSION_CODENAME)"
         ;;
+        *)
     esac
     # check operating system version
     case "${CD_OS_ID}" in
@@ -104,7 +108,9 @@ cd_set_environment_variables () {
                 *) cd_error_os "CD_OS_VERSION" ;;
             esac
         ;;
+        *)
     esac
+    cd_split
     cd_echo "CD_OS_ID" "CD_OS_VERSION"
     # universal
     CD_DNS_FILE="/etc/resolv.conf"
@@ -133,6 +139,7 @@ cd_set_environment_variables () {
             CD_CA_ROOT="/usr/local/share/ca-certificates"
             CD_CMD_CA="update-ca-certificates"
         ;;
+        *)
     esac
     cd_split
     cd_echo "CD_CA_ROOT" "CD_CMD_CA"
@@ -150,6 +157,7 @@ cd_set_environment_variables () {
         "${CD_OS_ARCH}")
             CD_PM="${CD_PM_PACMAN}"
         ;;
+        *)
     esac
     cd_split
     cd_echo "CD_PM"
@@ -223,6 +231,7 @@ Dir::Etc::SourceParts \"\";
 Acquire::https::Verify-Peer False;
 "
         ;;
+        *)
     esac
     cd_split
     cd_echo "CD_PM_CLEAN" \
@@ -252,34 +261,36 @@ Acquire::https::Verify-Peer False;
         "${CD_OS_UBUNTU}")
             CD_URL_DEFAULT="http://archive.ubuntu.com/ubuntu"
         ;;
+        *)
     esac
     CD_URL_CHOSEN="${CD_URL_DEFAULT}"
     case "${CD_OS_ID}" in
         "${CD_OS_ALMA}")
-            [ "${CD_URL_ALMA}" ] && CD_URL_CHOSEN="${CD_URL_ALMA}"
+            [ -n "${CD_URL_ALMA}" ] && CD_URL_CHOSEN="${CD_URL_ALMA}"
         ;;
         "${CD_OS_ALPINE}")
-            [ "${CD_URL_ALPINE}" ] && CD_URL_CHOSEN="${CD_URL_ALPINE}"
+            [ -n "${CD_URL_ALPINE}" ] && CD_URL_CHOSEN="${CD_URL_ALPINE}"
         ;;
         "${CD_OS_ARCH}")
-            [ "${CD_URL_ARCH}" ] && CD_URL_CHOSEN="${CD_URL_ARCH}"
+            [ -n "${CD_URL_ARCH}" ] && CD_URL_CHOSEN="${CD_URL_ARCH}"
         ;;
         "${CD_OS_DEBIAN}")
-            [ "${CD_URL_DEBIAN}" ] && CD_URL_CHOSEN="${CD_URL_DEBIAN}" \
+            [ -n "${CD_URL_DEBIAN}" ] && CD_URL_CHOSEN="${CD_URL_DEBIAN}" \
             || CD_URL_CHOSEN="https://deb.debian.org/debian"
         ;;
         "${CD_OS_FEDORA}")
-            [ "${CD_URL_FEDORA}" ] && CD_URL_CHOSEN="${CD_URL_FEDORA}" \
+            [ -n "${CD_URL_FEDORA}" ] && CD_URL_CHOSEN="${CD_URL_FEDORA}" \
             || CD_URL_CHOSEN="https://rpmfind.net/linux/fedora/linux/releases"
         ;;
         "${CD_OS_ROCKY}")
-            [ "${CD_URL_ROCKY}" ] && CD_URL_CHOSEN="${CD_URL_ROCKY}" \
+            [ -n "${CD_URL_ROCKY}" ] && CD_URL_CHOSEN="${CD_URL_ROCKY}" \
             || CD_URL_CHOSEN="https://dl.rockylinux.org/\$contentdir"
         ;;
         "${CD_OS_UBUNTU}")
-            [ "${CD_URL_UBUNTU}" ] && CD_URL_CHOSEN="${CD_URL_UBUNTU}" \
+            [ -n "${CD_URL_UBUNTU}" ] && CD_URL_CHOSEN="${CD_URL_UBUNTU}" \
             || CD_URL_CHOSEN="https://ubuntu.mirrors.ovh.net/ubuntu"
         ;;
+        *)
     esac
     cd_split
     cd_echo "CD_URL_DEFAULT" "CD_URL_CHOSEN"
@@ -301,6 +312,7 @@ Acquire::https::Verify-Peer False;
             case "${CD_OS_VERSION}" in
                 "bookworm") CD_PYTHON_COMMAND="python3.11" ;;
                 "bullseye") CD_PYTHON_COMMAND="python3.9" ;;
+                *)
             esac
             CD_PYTHON_PACKAGE="python3"
         ;;
@@ -312,9 +324,11 @@ Acquire::https::Verify-Peer False;
             case "${CD_OS_VERSION}" in
                 "noble") CD_PYTHON_COMMAND="python3.12" ;;
                 "jammy") CD_PYTHON_COMMAND="python3.10" ;;
+                *)
             esac
             CD_PYTHON_PACKAGE="python3"
         ;;
+        *)
     esac
     # set python packages
     case "${CD_OS_ID}" in
@@ -327,19 +341,20 @@ Acquire::https::Verify-Peer False;
         "${CD_OS_DEBIAN}"|"${CD_OS_UBUNTU}")
             CD_PYTHON_PACKAGES="/usr/lib/${CD_PYTHON_ALIAS}/dist-packages"
         ;;
+        *)
     esac
     cd_split
     cd_echo "CD_PYTHON_COMMAND" "CD_PYTHON_PACKAGE" "CD_PYTHON_PACKAGES"
     # variables
-    [ "${CD_CA_1}" ] && CD_CA=true
+    [ -n "${CD_CA_1}" ] && CD_CA=true
     # continuous integration platform
-    if [ "${GITHUB_ACTIONS}" ] ; then
+    if [ -n "${GITHUB_ACTIONS}" ] ; then
         # github → gitea → forgejo
         CD_SERVER_URL="${GITHUB_SERVER_URL}"
         CD_PROJECTS_GROUP="$(dirname "${GITHUB_REPOSITORY}")"
         CD_PROJECT_NAME="$(basename "${GITHUB_REPOSITORY}")"
         CD_PROJECT_BRANCH="${GITHUB_REF_NAME}"
-    elif [ "${GITLAB_CI}" ] ; then
+    elif [ -n "${GITLAB_CI}" ] ; then
         # gitlab
         CD_SERVER_URL="${CI_SERVER_URL}"
         CD_PROJECTS_GROUP="$(dirname "${CI_PROJECT_PATH}")"
@@ -349,13 +364,12 @@ Acquire::https::Verify-Peer False;
         # unsupported
         cd_error_ci "ø"
     fi
-    [ "${CD_SERVER_URL}" ] || cd_error_ci "CD_SERVER_URL"
-    [ "${CD_PROJECTS_GROUP}" ] || cd_error_ci "CD_PROJECTS_GROUP"
-    [ "${CD_PROJECT_NAME}" ] || cd_error_ci "CD_PROJECT_NAME"
-    [ "${CD_PROJECT_BRANCH}" ] || cd_error_ci "CD_PROJECT_BRANCH"
+    [ -n "${CD_SERVER_URL}" ] || cd_error_ci "CD_SERVER_URL"
+    [ -n "${CD_PROJECTS_GROUP}" ] || cd_error_ci "CD_PROJECTS_GROUP"
+    [ -n "${CD_PROJECT_NAME}" ] || cd_error_ci "CD_PROJECT_NAME"
+    [ -n "${CD_PROJECT_BRANCH}" ] || cd_error_ci "CD_PROJECT_BRANCH"
     #
     CD_PROJECTS_URL="${CD_SERVER_URL}/${CD_PROJECTS_GROUP}"
-    CD_PROJECT_URL="${CD_PROJECTS_URL}/${CD_PROJECT_NAME}"
     #
     cd_split
     cd_echo "CD_CA"
@@ -363,40 +377,42 @@ Acquire::https::Verify-Peer False;
     cd_echo "CD_SERVER_URL" \
         "CD_PROJECTS_GROUP" "CD_PROJECT_NAME" "CD_PROJECT_BRANCH"
     cd_split
-    cd_echo "CD_PROJECTS_URL" "CD_PROJECT_URL"
+    cd_echo "CD_PROJECTS_URL"
     # TODO move to Python
     case "${CD_PM}" in
         "${CD_PM_APK}"|"${CD_PM_APT}") CD_PKG_SSH="openssh-client" ;;
         "${CD_PM_DNF}") CD_PKG_SSH="openssh-clients" ;;
         "${CD_PM_PACMAN}") CD_PKG_SSH="openssh" ;;
+        *)
     esac
 }
 
 cd_set_packages_repositories () {
-local expression
-local file
     cd_step "Set packages repositories"
     case "${CD_OS_ID}" in
         "${CD_OS_ALMA}")
             case "${CD_OS_VERSION}" in
-                "8") file="/etc/yum.repos.d/almalinux.repo" ;;
-                "9") file="/etc/yum.repos.d/almalinux-baseos.repo" ;;
+                "8") \
+cd_set_packages_repositories__file="/etc/yum.repos.d/almalinux.repo" ;;
+                "9") \
+cd_set_packages_repositories__file="/etc/yum.repos.d/almalinux-baseos.repo" ;;
+                *)
             esac
-            cd_sed "${file}" \
+            cd_sed "${cd_set_packages_repositories__file}" \
             "|^mirrorlist|# mirrorlist|" \
             "|${CD_URL_DEFAULT}|${CD_URL_CHOSEN}|" \
             "|^# baseurl|baseurl|"
         ;;
         "${CD_OS_ALPINE}")
-            file="/etc/apk/repositories"
-            cd_write "${file}" "\
+            cd_set_packages_repositories__file="/etc/apk/repositories"
+            cd_write "${cd_set_packages_repositories__file}" "\
 ${CD_URL_CHOSEN}/v${CD_OS_VERSION}/main
 ${CD_URL_CHOSEN}/v${CD_OS_VERSION}/community
 "
         ;;
         "${CD_OS_DEBIAN}")
-            file="/etc/apt/sources.list"
-            cd_write "${file}" "\
+            cd_set_packages_repositories__file="/etc/apt/sources.list"
+            cd_write "${cd_set_packages_repositories__file}" "\
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION} main
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION}-backports main
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION}-updates main
@@ -405,23 +421,27 @@ deb ${CD_URL_CHOSEN}-security ${CD_OS_VERSION}-security main
         ;;
         "${CD_OS_ROCKY}")
             case "${CD_OS_VERSION}" in
-                "8") file="/etc/yum.repos.d/Rocky-BaseOS.repo" ;;
-                "9") file="/etc/yum.repos.d/rocky.repo" ;;
+                "8") \
+cd_set_packages_repositories__file="/etc/yum.repos.d/Rocky-BaseOS.repo" ;;
+                "9") \
+cd_set_packages_repositories__file="/etc/yum.repos.d/rocky.repo" ;;
+                *)
             esac
-            cd_sed "${file}" \
+            cd_sed "${cd_set_packages_repositories__file}" \
             "|^mirrorlist|# mirrorlist|" \
             "|${CD_URL_DEFAULT}|${CD_URL_CHOSEN}|" \
             "|^#baseurl|baseurl|"
         ;;
         "${CD_OS_UBUNTU}")
-            file="/etc/apt/sources.list"
-            cd_write "${file}" "\
+            cd_set_packages_repositories__file="/etc/apt/sources.list"
+            cd_write "${cd_set_packages_repositories__file}" "\
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION} main
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION}-backports main
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION}-updates main
 deb ${CD_URL_CHOSEN} ${CD_OS_VERSION}-security main
 "
         ;;
+        *)
     esac
 }
 
@@ -432,6 +452,7 @@ cd_set_packages_configuration () {
         "${CD_OS_DEBIAN}"|"${CD_OS_UBUNTU}")
             export DEBIAN_FRONTEND="noninteractive"
         ;;
+        *)
     esac
 }
 
@@ -439,11 +460,12 @@ cd_set_packages_configuration () {
 
 cd_list_working_directory () {
     cd_step "List working directory"
-    cd_ls "$(realpath .)"
+    cd_list_working_directory__path="$(realpath .)"
+    cd_ls "${cd_list_working_directory__path}"
 }
 
 cd_set_https_verification_off () {
-    if [ "${CD_CA}" -o "${CD_PM}" = "${CD_PM_APT}" ] ; then
+    if [ -n "${CD_CA}" ] || [ "${CD_PM}" = "${CD_PM_APT}" ] ; then
         cd_step "Set HTTPS verification off"
         cd_mkdir "$(dirname "${CD_PM_HTTPS_PATH}")"
         cd_write "${CD_PM_HTTPS_PATH}" "${CD_PM_HTTPS_TEXT}"
@@ -451,14 +473,13 @@ cd_set_https_verification_off () {
 }
 
 cd_set_dns_resolving () {
-local server
-local text=""
     cd_step "Set DNS resolving"
-    for server in ${CD_DNS} ; do
-        text="${text}nameserver ${server}
+    for cd_set_dns_resolving__server in ${CD_DNS} ; do
+        cd_set_dns_resolving__text="${cd_set_dns_resolving__text}\
+nameserver ${cd_set_dns_resolving__server}
 "
     done
-    cd_write "${CD_DNS_FILE}" "${text}"
+    cd_write "${CD_DNS_FILE}" "${cd_set_dns_resolving__text}"
 }
 
 cd_update_packages_catalog () {
@@ -477,20 +498,22 @@ cd_install_ca_certificates () {
 }
 
 cd_write_ca_certificates () {
-local index
-local path
-local text
     cd_step "Write CA certificates"
     cd_mkdir "${CD_CA_ROOT}"
-    index=1
-    eval "text=\"\${CD_CA_${index}}\""
-    while [ "${text}" ] ; do
-        path="${CD_CA_ROOT}/${index}.crt"
+    cd_write_ca_certificates__index=1
+    eval "cd_write_ca_certificates__text=\
+\"\${CD_CA_${cd_write_ca_certificates__index}}\""
+    while [ -n "${cd_write_ca_certificates__text}" ] ; do
+        cd_write_ca_certificates__path="\
+${CD_CA_ROOT}/${cd_write_ca_certificates__index}.crt"
         cd_split
-        cd_write "${path}" "${text}"
-        cd_openssl "${path}"
-        index=$((index+1))
-        eval "text=\"\${CD_CA_${index}}\""
+        cd_write \
+        "${cd_write_ca_certificates__path}" \
+        "${cd_write_ca_certificates__text}"
+        cd_openssl "${cd_write_ca_certificates__path}"
+        cd_write_ca_certificates__index=$((cd_write_ca_certificates__index+1))
+        eval "cd_write_ca_certificates__text=\
+\"\${CD_CA_${cd_write_ca_certificates__index}}\""
     done
 }
 
@@ -539,169 +562,174 @@ cd_clean_packages_cache () {
 }
 
 cd_install_python_modules () {
-local path
-local repository
-local root
-local url
     cd_step "Install Python modules"
-    root="$(mktemp --directory)" || exit
-    echo "→ ${root}"
-    for repository in "${CD_GIT_CHILD}" "${CD_GIT_PARENT}" ; do
+    cd_install_python_modules__root="$(mktemp --directory)" || exit
+    echo "→ ${cd_install_python_modules__root}"
+    for cd_install_python_modules__repository \
+    in "${CD_GIT_CHILD}" "${CD_GIT_PARENT}" ; do
         cd_split
-        url="${CD_PROJECTS_URL}/${repository}"
-        echo -n "\
-${url}
-↓
-"
+        cd_install_python_modules__url="\
+${CD_PROJECTS_URL}/${cd_install_python_modules__repository}"
+        echo "\
+${cd_install_python_modules__url}
+↓"
         git clone \
-        "${url}" "${root}/${repository}" \
+        "${cd_install_python_modules__url}" \
+        "${cd_install_python_modules__root}\
+/${cd_install_python_modules__repository}" \
         || exit
-        path="${root}/${repository}/${repository}"
-        echo -n "\
-${path}
+        cd_install_python_modules__path="\
+${cd_install_python_modules__root}\
+/${cd_install_python_modules__repository}\
+/${cd_install_python_modules__repository}"
+        echo "\
+${cd_install_python_modules__path}
 ↓
-${CD_PYTHON_PACKAGES}
-"
+${CD_PYTHON_PACKAGES}"
         cp --recursive \
-        "${path}" "${CD_PYTHON_PACKAGES}" \
+        "${cd_install_python_modules__path}" "${CD_PYTHON_PACKAGES}" \
         || exit
     done
     cd_split
     cd_ls "${CD_PYTHON_PACKAGES}"
     cd_split
-    cd_rm "${root}"
+    cd_rm "${cd_install_python_modules__root}"
 }
 
 cd_write_python_module () {
     cd_step "Write Python module"
-    cd_write "${CD_PYTHON_PACKAGES}/env.py" "\
-$(cd_echo CD_OPEN CD_DOWN)
-$(cd_echo CD_VERT CD_SPLT)
-$(cd_echo CD___UP CD_SHUT)
-
-$(cd_echo CD_OS_ID CD_OS_VERSION)
-
+    for cd_write_python_module__variable \
+    in OPEN DOWN VERT SPLT __UP SHUT OS_ID OS_VERSION ; do
+        cd_write_python_module__value="\
+$(cd_echo "CD_${cd_write_python_module__variable}")"
+        cd_write_python_module__text="${cd_write_python_module__text}\
+${cd_write_python_module__value}
+"
+    done
+    cd_write "${CD_PYTHON_PACKAGES}/env.py" "${cd_write_python_module__text}\
 CD_STEP = $((CD_STEP+1))
 "
 }
 
 cd_switch_to_python () {
-local path
     cd_step "Switch to Python"
-    #
-    path="$(realpath "${0}")"
-    echo -n "\
-${path}
+    echo "\
+${CD_PATH}
 ↓
-${CD_PYTHON_PACKAGES}/${CD_GIT_CHILD}
-"
+${CD_PYTHON_PACKAGES}/${CD_GIT_CHILD}"
     "${CD_PYTHON_ALIAS}" -m "${CD_GIT_CHILD}" "${@}"
 }
 
 # functions
 
 cd_cat () {
-    if [ -f "${1}" ] ; then
-        cd_open "${1}"
-        cat "${1}" || exit
-        cd_shut "${1}"
+    cd_cat__file="${1}"
+    if [ -n "${cd_cat__file}" ] ; then
+        cd_open "${cd_cat__file}"
+        cat "${cd_cat__file}" || exit
+        cd_shut "${cd_cat__file}"
     fi
 }
 
 cd_echo () {
-local name
-    if [ "${1}" ] ; then
-        for name in "${@}" ; do
-            eval "echo ${name} = \\\"\${${name}}\\\""
+    if [ -n "${1}" ] ; then
+        for cd_echo__name in "${@}" ; do
+            eval "echo ${cd_echo__name} = \\\"\${${cd_echo__name}}\\\""
         done
     fi
 }
 
 cd_error_ci () {
-    echo "× CI: ${1}"
-    exit ${CD_ERROR_CI}
+    echo "× CI: ${*}"
+    exit "${CD_ERROR_CI}"
 }
 
 cd_error_os () {
-local variable="${1}"
-    echo -n "× OS: "
-    cd_echo "${variable}"
-    exit ${CD_ERROR_OS}
+    cd_error_os__variable="${1}"
+    printf "× OS: "
+    cd_echo "${cd_error_os__variable}"
+    exit "${CD_ERROR_OS}"
 }
 
 cd_grep_os () {
-local variable="${1}"
-    if [ "${variable}" ] ; then
-        grep "^${variable}=" "/etc/os-release" \
-        | sed "s|^${variable}=||" \
+    cd_grep_os__variable="${1}"
+    if [ -n "${cd_grep_os__variable}" ] ; then
+        grep "^${cd_grep_os__variable}=" "/etc/os-release" \
+        | sed "s|^${cd_grep_os__variable}=||" \
         | sed "s|^\"\(.*\)\"$|\1|"
     fi
 }
 
 cd_install_package () {
-    if [ "${1}" ] ; then
-        ${CD_PM_INSTALL} "${1}" || exit
+    cd_install_package__name="${1}"
+    if [ -n "${cd_install_package__name}" ] ; then
+        ${CD_PM_INSTALL} "${cd_install_package__name}" || exit
     fi
 }
 
 cd_ln_python () {
-local command="${1}"
-    if [ "${command}" ] ; then
-        echo "→ ${CD_PYTHON_ALIAS} → ${command}"
-        ln -f -s "${command}" "/usr/bin/${CD_PYTHON_ALIAS}" || exit
+    cd_ln_python__command="${1}"
+    if [ -n "${cd_ln_python__command}" ] ; then
+        echo "→ ${CD_PYTHON_ALIAS} → ${cd_ln_python__command}"
+        ln -f -s "${cd_ln_python__command}" "/usr/bin/${CD_PYTHON_ALIAS}" \
+        || exit
     fi
 }
 
 cd_ls () {
-    if [ -d "${1}" ] ; then
-        cd_open "${1}"
-        ls -a -l "${1}" || exit
-        cd_shut "${1}"
+    cd_ls__path="${1}"
+    if [ -n "${cd_ls__path}" ] ; then
+        cd_open "${cd_ls__path}"
+        ls -a -l "${cd_ls__path}" || exit
+        cd_shut "${cd_ls__path}"
     fi
 }
 
 cd_mkdir () {
-    if [ "${1}" ] ; then
-        echo "→ ${1}"
-        mkdir --parents "${1}" || exit
+    cd_mkdir__path="${1}"
+    if [ -n "${cd_mkdir__path}" ] ; then
+        echo "→ ${cd_mkdir__path}"
+        mkdir --parents "${cd_mkdir__path}" || exit
     fi
 }
 
 cd_open () {
-    echo "${CD_OPEN}${@}"
+    echo "${CD_OPEN}${*}"
 }
 
 cd_openssl () {
-local file="${1}"
-    if [ -f "${file}" ] ; then
-        openssl x509 -noout -text -in "${file}" || exit
+    cd_openssl__file="${1}"
+    if [ -f "${cd_openssl__file}" ] ; then
+        openssl x509 \
+        -in "${cd_openssl__file}" \
+        -noout -text \
+        || exit
     fi
 }
 
 cd_rm () {
-local path="${1}"
-    if [ -e "${path}" ] ; then
-        echo "← ${path}"
-        rm -r "${path}" || exit
+    cd_rm__path="${1}"
+    if [ -e "${cd_rm__path}" ] ; then
+        echo "← ${cd_rm__path}"
+        rm -r "${cd_rm__path}" || exit
     fi
 }
 
 cd_sed () {
-local expression
-local file="${1}"
-shift
-    if [ -f "${file}" ] ; then
-        cd_cat "${file}"
-        for expression in "${@}" ; do
-            sed --in-place "s${expression}g" "${file}" \
-            && cd_cat "${file}" \
+    cd_sed__file="${1}"
+    shift
+    if [ -f "${cd_sed__file}" ] ; then
+        cd_cat "${cd_sed__file}"
+        for cd_sed__regex in "${@}" ; do
+            sed --in-place "s${cd_sed__regex}g" "${cd_sed__file}" \
+            && cd_cat "${cd_sed__file}" \
             || exit
         done
     fi
 }
 
 cd_shut () {
-    echo "${CD_SHUT}${@}"
+    echo "${CD_SHUT}${*}"
 }
 
 cd_split () {
@@ -710,21 +738,20 @@ cd_split () {
 
 cd_step () {
     CD_STEP=$((CD_STEP+1))
-    echo -n "\
+    echo "\
 ${CD_DOWN}
-${CD_VERT} ${CD_STEP} ${@}
-${CD___UP}
-"
+${CD_VERT} ${CD_STEP} ${*}
+${CD___UP}"
 }
 
 cd_write () {
-local file="${1}"
-local text="${2}"
-    if [ "${file}" ] ; then
-        [ -f "${file}" ] && cd_cat "${file}"
-        echo "→ ${1}"
-        echo -n "${text}" > "${file}" || exit
-        cd_cat "${file}"
+    cd_write__file="${1}"
+    cd_write__text="${2}"
+    if [ -n "${cd_write__file}" ] ; then
+        [ -f "${cd_write__file}" ] && cd_cat "${cd_write__file}"
+        echo "→ ${cd_write__file}"
+        printf "%s" "${cd_write__text}" > "${cd_write__file}" || exit
+        cd_cat "${cd_write__file}"
     fi
 }
 
diff --git a/cd/__init__.py b/cd/__init__.py
index befcf35..4ea730e 100644
--- a/cd/__init__.py
+++ b/cd/__init__.py
@@ -6,7 +6,7 @@ import env
 from rwx import fs
 from rwx import ps
 
-COMMANDS_PREFIX = 'cd-'
+COMMANDS_PREFIX = "cd-"
 
 projects = Projects(os.environ)
 project = Project(projects)
@@ -17,8 +17,8 @@ def cd_browse_workspace():
 
 
 def cd_build_project():
-    for extension in ['py', 'sh']:
-        path = os.path.join(project.root, f'build.{extension}')
+    for extension in ["py", "sh"]:
+        path = os.path.join(project.root, f"build.{extension}")
         if os.path.exists(path):
             ps.run(path)
             break
@@ -27,14 +27,14 @@ def cd_build_project():
 
 
 def cd_clone_branch():
-    print(f'''\
+    print(f"""\
 {project.url}
 ↓
-''', end=str(), flush=True)
-    ps.run('git',
-        'clone',
-        '--branch', project.branch,
-        '--',
+""", end="", flush=True)
+    ps.run("git",
+        "clone",
+        "--branch", project.branch,
+        "--",
         project.url,
         project.root,
     )
@@ -42,25 +42,25 @@ def cd_clone_branch():
 
 def cd_list_environment():
     for variable, value in sorted(projects.environment.items()):
-        print(variable, '=', value)
+        print(variable, "=", value)
 
 
 def cd_synchronize():
-    host = 'rwx.work'
-    source = 'out'
-    user = 'cd'
+    host = "rwx.work"
+    source = "out"
+    user = "cd"
     #
-    root = os.sep.join([str(),
+    root = os.sep.join(["",
                         user, project.branch, projects.group, project.name])
     #
-    target = f'{user}@{host}:{root}'
-    ps.run('rsync',
-        '--archive',
-        '--delete-before',
-        '--verbose',
-        f'{source}/',
-        f'{target}/',
-        '--dry-run',
+    target = f"{user}@{host}:{root}"
+    ps.run("rsync",
+        "--archive",
+        "--delete-before",
+        "--verbose",
+        f"{source}/",
+        f"{target}/",
+        "--dry-run",
     )
 
 
@@ -84,38 +84,38 @@ def cat(file: str):
 
 
 def install_commands(path):
-    step('Install commands')
-    user = '/usr/local/bin'
+    step("Install commands")
+    user = "/usr/local/bin"
     for command in [
-        'browse-workspace',
-        'build-project',
-        'clone-branch',
-        'list-environment',
-        'synchronize',
+        "browse-workspace",
+        "build-project",
+        "clone-branch",
+        "list-environment",
+        "synchronize",
     ]:
         print(command)
-        os.symlink(path, os.path.join(user, f'{COMMANDS_PREFIX}{command}'))
+        os.symlink(path, os.path.join(user, f"{COMMANDS_PREFIX}{command}"))
 
 
 def set_ssh(*arguments):
-    step('Set SSH')
+    step("Set SSH")
     #
     ssh_key, ssh_hosts = arguments
     #
-    ssh_type = 'ed25519'
+    ssh_type = "ed25519"
     #
-    home = os.path.expanduser('~')
+    home = os.path.expanduser("~")
     #
-    ssh = os.path.join(home, '.ssh')
+    ssh = os.path.join(home, ".ssh")
     os.makedirs(ssh, exist_ok=True)
     os.chmod(ssh, 0o700)
     #
-    key = os.path.join(ssh, f'id_{ssh_type}')
+    key = os.path.join(ssh, f"id_{ssh_type}")
     if ssh_key:
         fs.write(key, ssh_key)
         os.chmod(key, 0o400)
     #
-    known = os.path.join(ssh, 'known_hosts')
+    known = os.path.join(ssh, "known_hosts")
     if ssh_hosts:
         fs.write(known, ssh_hosts)
         os.chmod(known, 0o400)
@@ -125,12 +125,12 @@ def set_ssh(*arguments):
 
 
 def open(*arguments):
-    print(env.CD_OPEN, end=str())
+    print(env.CD_OPEN, end="")
     print(*arguments, flush=True)
 
 
 def shut(*arguments):
-    print(env.CD_SHUT, end=str())
+    print(env.CD_SHUT, end="")
     print(*arguments, flush=True)