diff --git a/cd.sh b/cd.sh
index 622af39..a9b5700 100644
--- a/cd.sh
+++ b/cd.sh
@@ -37,27 +37,19 @@ cd_main () {
 # steps
 
 cd_set_environment_variables () {
-local index
-local text
     cd_step "Set environment variables"
     #
-    index=1
-    eval "text=\"\${CD_CA_${index}}\""
-    while [ "${text}" ] ; do
-        CD_CA=${index}
-        index=$((index+1))
-        eval "text=\"\${CD_CA_${index}}\""
-    done
+    [ "${CD_CA_1}" ] && CD_CA=true
     #
     case "$(cd_grep_os ID)" in
-        "debian")
-            CD_OS_ID="${CD_OS_DEBIAN}"
-            CD_OS_VERSION="$(cd_grep_os VERSION_CODENAME)"
-        ;;
         "almalinux")
             CD_OS_ID="${CD_OS_ALMA}"
             CD_OS_VERSION="$(cd_grep_os VERSION_ID)"
         ;;
+        "debian")
+            CD_OS_ID="${CD_OS_DEBIAN}"
+            CD_OS_VERSION="$(cd_grep_os VERSION_CODENAME)"
+        ;;
     esac
     #
     CD_CA_PACKAGE="ca-certificates"
@@ -65,18 +57,6 @@ local text
     CD_GIT_PACKAGE="git"
     #
     case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}")
-            CD_OS_REPO="${CD_DEFAULT_REPO_DEBIAN}"
-            [ "${CD_REPO_DEBIAN}" ] && CD_OS_REPO="${CD_REPO_DEBIAN}"
-            case "${CD_OS_VERSION}" in
-                "bookworm"|"bullseye") cd_nop ;;
-                *) cd_error_os "CD_OS_VERSION" ;;
-            esac
-            CD_CA_ROOT="/usr/local/share/ca-certificates"
-            CD_PYTHON_COMMAND="python3"
-            CD_PYTHON_PACKAGE="python3"
-            CD_PYTHON_PACKAGES="/usr/lib/python3/dist-packages"
-        ;;
         "${CD_OS_ALMA}")
             CD_OS_REPO="${CD_DEFAULT_REPO_ALMA}"
             [ "${CD_REPO_ALMA}" ] && CD_OS_REPO="${CD_REPO_ALMA}"
@@ -85,10 +65,55 @@ local text
                 *) cd_error_os "CD_OS_VERSION" ;;
             esac
             CD_CA_ROOT="/etc/pki/ca-trust/source/anchors"
+            CD_CMD_CA="update-ca-trust"
+            CD_CMD_CLEAN="dnf clean all"
+            CD_CMD_UPDATE="dnf makecache"
+            CD_CMD_UPGRADE="dnf upgrade --assumeyes"
+            CD_PKG_PKG=""
+            CD_PM_CONF_PATH="/etc/dnf/dnf.conf"
+            CD_PM_CONF_TEXT="\
+[main]
+best=True
+clean_requirements_on_remove=True
+gpgcheck=1
+installonly_limit=3
+skip_if_unavailable=False
+"
+            CD_PM_HTTPS_PATH="/etc/dnf/dnf.conf.d/https.conf"
+            CD_PM_HTTPS_TEXT="sslverify=False"
             CD_PYTHON_COMMAND="python3.11"
             CD_PYTHON_PACKAGE="python3.11"
             CD_PYTHON_PACKAGES="/usr/lib64/python3.11/site-packages"
         ;;
+        "${CD_OS_DEBIAN}")
+            export DEBIAN_FRONTEND="noninteractive"
+            #
+            CD_OS_REPO="${CD_DEFAULT_REPO_DEBIAN}"
+            [ "${CD_REPO_DEBIAN}" ] && CD_OS_REPO="${CD_REPO_DEBIAN}"
+            case "${CD_OS_VERSION}" in
+                "bookworm"|"bullseye") cd_nop ;;
+                *) cd_error_os "CD_OS_VERSION" ;;
+            esac
+            CD_CA_ROOT="/usr/local/share/ca-certificates"
+            CD_CMD_CA="update-ca-certificates"
+            CD_CMD_CLEAN="apt-get clean"
+            CD_CMD_UPDATE="apt-get update"
+            CD_CMD_UPGRADE="apt-get upgrade --assume-yes"
+            CD_PKG_PKG="apt-utils"
+            CD_PM_CONF_PATH="/etc/apt/apt.conf.d/apt.conf"
+            CD_PM_CONF_TEXT="\
+Acquire::Check-Valid-Until True;
+APT::Get::Show-Versions True;
+APT::Install-Recommends False;
+APT::Install-Suggests False;
+Dir::Etc::SourceParts \"\";
+"
+            CD_PM_HTTPS_PATH="/etc/apt/apt.conf.d/https"
+            CD_PM_HTTPS_TEXT="Acquire::https::Verify-Peer False;"
+            CD_PYTHON_COMMAND="python3"
+            CD_PYTHON_PACKAGE="python3"
+            CD_PYTHON_PACKAGES="/usr/lib/python3/dist-packages"
+        ;;
         *) cd_error_os "CD_OS_ID" ;;
     esac
     # continuous integration platform
@@ -149,14 +174,6 @@ local expression
 local file
     cd_step "Set packages repositories"
     case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}")
-            cd_write "/etc/apt/sources.list" "\
-deb ${CD_OS_REPO} ${CD_OS_VERSION} main
-deb ${CD_OS_REPO} ${CD_OS_VERSION}-backports main
-deb ${CD_OS_REPO} ${CD_OS_VERSION}-updates main
-deb ${CD_OS_REPO}-security ${CD_OS_VERSION}-security main
-"
-        ;;
         "${CD_OS_ALMA}")
             file="/etc/yum.repos.d/almalinux.repo"
             cd_sed "${file}" \
@@ -165,58 +182,40 @@ deb ${CD_OS_REPO}-security ${CD_OS_VERSION}-security main
             "|^# baseurl|baseurl|"
             cd_cat "${file}"
         ;;
+        "${CD_OS_DEBIAN}")
+            cd_write "/etc/apt/sources.list" "\
+deb ${CD_OS_REPO} ${CD_OS_VERSION} main
+deb ${CD_OS_REPO} ${CD_OS_VERSION}-backports main
+deb ${CD_OS_REPO} ${CD_OS_VERSION}-updates main
+deb ${CD_OS_REPO}-security ${CD_OS_VERSION}-security main
+"
+        ;;
     esac
 }
 
+# agnostic steps
+
 cd_set_packages_configuration () {
     cd_step "Set packages configuration"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}")
-            export DEBIAN_FRONTEND="noninteractive"
-            cd_write "/etc/apt/apt.conf.d/apt.conf" "\
-Acquire::Check-Valid-Until True;
-APT::Get::Show-Versions True;
-APT::Install-Recommends False;
-APT::Install-Suggests False;
-Dir::Etc::SourceParts \"\";
-"
-        ;;
-        "${CD_OS_ALMA}") cd_mkdir "/etc/dnf/dnf.conf.d" ;;
-    esac
+    cd_write "${CD_PM_CONF_PATH}" "${CD_PM_CONF_TEXT}"
 }
 
 cd_set_https_verification_off () {
-    if [ "${CD_CA}" ] ; then
+    if [ "${CD_CA}" -o "${CD_OS_ID}" = "${CD_OS_DEBIAN}" ] ; then
         cd_step "Set HTTPS verification off"
-        case "${CD_OS_ID}" in
-            "${CD_OS_DEBIAN}")
-                cd_write "/etc/apt/apt.conf.d/https" "\
-Acquire::https::Verify-Peer False;
-"
-            ;;
-            "${CD_OS_ALMA}")
-                cd_write "/etc/dnf/dnf.conf.d/https.conf" "\
-sslverify=False
-"
-            ;;
-        esac
+        cd_mkdir "$(dirname "${CD_PM_HTTPS_PATH}")"
+        cd_write "${CD_PM_HTTPS_PATH}" "${CD_PM_HTTPS_TEXT}"
     fi
 }
 
 cd_update_packages_catalog () {
     cd_step "Update packages catalog"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}") apt-get update || exit ;;
-        "${CD_OS_ALMA}") dnf makecache || exit ;;
-    esac
+    ${CD_CMD_UPDATE} || exit
 }
 
 cd_install_packages_tools () {
     cd_step "Install packages tools"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}") cd_install_package "apt-utils" ;;
-        "${CD_OS_ALMA}") cd_nop ;;
-    esac
+    cd_install_package "${CD_PKG_PKG}"
 }
 
 cd_install_ca_certificates () {
@@ -227,7 +226,7 @@ cd_install_ca_certificates () {
 cd_write_ca_certificates () {
 local index
 local text
-    cd_step "Copy CA"
+    cd_step "Write CA certificates"
     cd_mkdir "${CD_CA_ROOT}"
     index=1
     eval "text=\"\${CD_CA_${index}}\""
@@ -239,29 +238,20 @@ local text
 }
 
 cd_update_ca_certificates () {
-    cd_step "Update CA"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}") update-ca-certificates || exit ;;
-        "${CD_OS_ALMA}") update-ca-trust || exit ;;
-    esac
+    cd_step "Update CA certificates"
+    ${CD_CMD_CA} || exit
 }
 
 cd_set_https_verification_on () {
-    if [ "${CD_CA}" ] ; then
+    if [ "${CD_CA}" -o "${CD_OS_ID}" = "${CD_OS_DEBIAN}" ] ; then
         cd_step "Set HTTPS verification on"
-        case "${CD_OS_ID}" in
-            "${CD_OS_DEBIAN}") cd_rm "/etc/apt/apt.conf.d/https" ;;
-            "${CD_OS_ALMA}") cd_rm "/etc/dnf/dnf.conf.d/https.conf" ;;
-        esac
+        cd_rm "${CD_PM_HTTPS_PATH}"
     fi
 }
 
 cd_upgrade_packages () {
     cd_step "Upgrade packages"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}") apt-get upgrade --assume-yes || exit ;;
-        "${CD_OS_ALMA}") dnf upgrade --assumeyes || exit ;;
-    esac
+    ${CD_CMD_UPGRADE} || exit
 }
 
 cd_install_git () {
@@ -276,10 +266,7 @@ cd_install_python () {
 
 cd_clean_packages_cache () {
     cd_step "Clean packages cache"
-    case "${CD_OS_ID}" in
-        "${CD_OS_DEBIAN}") apt-get clean || exit ;;
-        "${CD_OS_ALMA}") dnf clean all || exit ;;
-    esac
+    ${CD_CMD_CLEAN} || exit
 }
 
 cd_install_python_modules () {
diff --git a/readme.md b/readme.md
index 5800715..51e54e5 100644
--- a/readme.md
+++ b/readme.md
@@ -29,8 +29,14 @@ from various CA, CI, OCI / OS.
 
 ## Tasks
 
-* first list working directory
+* write bats
+
 * handle cloning credentials
+* make steps more agnostic
+* show CA certificates as text
+* write Python bootstrap
+
+* first list working directory
 * integrate project repository cloning
 * override repository and framework locations
-* write Python bootstrap
+* reduce operating system version to major