diff --git a/cd.sh b/cd.sh
index 5f799d4..819404e 100644
--- a/cd.sh
+++ b/cd.sh
@@ -1,5 +1,3 @@
-#! /usr/bin/env bash
-
 CD_DNS_SERVERS=(
 '9.9.9.9'
 )
@@ -27,7 +25,7 @@ CD_STEP=0
 
 function cd_step {
     if [ "${1}" ] ; then
-        ((CD_STEP++))
+        CD_STEP=$((CD_STEP+1))
         echo "
  ↕ ${CD_STEP} ↔ ${1}
 "
@@ -44,7 +42,7 @@ local text="${2}"
     fi
 }
 
-function cd_set_dns_resolving {
+function cd_set_dns {
 local server
 local text=''
     cd_step "set name servers"
@@ -56,26 +54,18 @@ local text=''
     || exit
 }
 
-function cd_set_packages_configuration {
-    cd_step "configure package manager"
-    case "${CD_OS_NAME}" in
-        'debian')
-    cd_write '/etc/apt/apt.conf.d/apt.conf' "\
+function cd_main {
+    cd_set_dns
+
+cd_step "configure package manager"
+echo -n "\
 Acquire::Check-Valid-Until True;
 APT::Get::Show-Versions True;
 APT::Install-Recommends False;
 APT::Install-Suggests False;
-Dir::Etc::SourceParts \"\";
-"
-        ;;
-        *) exit 1 ;;
-    esac
-}
-
-function cd_main {
-    cd_set_dns_resolving
-    cd_set_packages_configuration
-
+Dir::Etc::SourceParts '';
+" > '/etc/apt/apt.conf.d/apt.conf' \
+|| exit
 cd_step "configure package repositories"
 echo -n "\
 deb https://deb.debian.org/debian bookworm main