diff --git a/shemum b/shemum
index 6036d6f..f60a354 100755
--- a/shemum
+++ b/shemum
@@ -3,6 +3,8 @@
 # Author: Adrian Erik Hoemann
 # Date: 9.18.2024
 
+# TODO: Implement operating system installer variable list.
+
 # Debug mode
 # To enable debug mode remove the comment.
 # Default: true
@@ -28,29 +30,53 @@ IMG_PATH="$ROOT_PATH/$OS_NAME/$OS_NAME.img"
 # Sources virtual machine specific values
 . "$ROOT_PATH/$OS_NAME/.env"
 
-# Defines install image repository.
-case $OS_NAME in
-  "openbsd")
-    INSTALL_IMG="https://cdn.openbsd.org/pub/OpenBSD/7.5/i386/cd75.iso"
-  ;;
-  "debian")
-    INSTALL_IMG=""
-  ;;
-  *)
-    echo "$OS_NAME is not an option" >&2
-    exit 1
-  ;;
-esac
-
 # Functions
 
+# Defines install image source
+def_os_source() {
+  case $OS_NAME in
+    "openbsd")
+      INSTALL_IMG="https://cdn.openbsd.org/pub/OpenBSD/7.5/i386/cd75.iso"
+    ;;
+    "debian")
+      INSTALL_IMG=""
+    ;;
+    *)
+      err_func "INSTALL_IMG for $OS_NAME not found"
+    ;;
+  esac
+}
+
+check_func() {
+  if [ -z $OS_NAME ]
+    err_func "Operating system is empty"
+  fi
+  if [ -z $INSTALL_IMG ]
+    info_func "$INSTALL_IMG is not set"
+  fi
+
+}
+
+err_func() {
+  printf "$@" >&2
+  exit 1
+}
+
+warn_func() {
+  printf "$@" >&2
+}
+
+info_func() {
+  printf "$@" >&1
+}
+
 # Virtual machine removal
-remove_func function { 
+remove_func() {
   rm -r $ROOT_PATH/$OS_NAME 
 }
 
 # Virtual machine start without a console
-start_func function {
+start_func() {
   qemu-system-x86_64 -boot c                            \
                        -display none                    \
                        -drive file=$IMG_PATH,format=raw \
@@ -58,7 +84,7 @@ start_func function {
 }
 
 # Virtual machine start with a console
-console_func function {
+console_func() {
   qemu-system-x86_64 -boot c                    \
                        -display curses            \
                        -drive file=$IMG_PATH,format=raw \
@@ -66,17 +92,17 @@ console_func function {
 }
 
 # Virtual machine initialization with a console
-init_func function {
+init_func() {
+  def_os_source
   mkdir -p "$ROOT_PATH/$OS_NAME"
   qemu-img create $IMG_PATH $DISK_SIZE
   if [ ! -f $ISO_PATH ] && [ ! -z $INSTALL_IMG ]; then
-    echo $INSTALL_IMG
+    info_func "Fetching $OSNAME installer at: $INSTALL_IMG"
     curl -o $ISO_PATH $INSTALL_IMG
   elif [ ! -z $INSTALL_IMG ]; then
-    echo "Current INSTALL_IMG for $OS_NAME: $ISO_PATH"
-  else:
-    echo "Install image path is missing" >&2
-    exit 1
+    info_func "Current INSTALL_IMG for $OS_NAME: $ISO_PATH"
+  else
+    err_func "Install image path is missing"
   fi
   qemu-system-x86_64 -boot d                          \
                     -display curses                   \
@@ -86,7 +112,7 @@ init_func function {
 }
 
 # Display usage
-usage_func function {
+usage_func() {
   printf "Usage: shemum [init] <virtual machine name> <disk size>"
   printf " init        initialize a virtual machine"
   printf " start       start a QEMU virtual machine without console output"