diff --git a/install_amavis.sh b/install_amavis.sh
index 10759a9..4e5c99a 100755
--- a/install_amavis.sh
+++ b/install_amavis.sh
@@ -60,6 +60,35 @@ echo_skipped() {
    echo -e "\033[80G[ \033[33m\033[1mskipped\033[m ]"
 }
 
+detect_os_1 () {
+
+   if $(which lsb_release > /dev/null 2>&1) ; then
+
+      os_dist="$(lsb_release -i | awk '{print tolower($3)}')"
+      os_version="$(lsb_release -r | awk '{print tolower($2)}')"
+      os_codename="$(lsb_release -c | awk '{print tolower($2)}')"
+
+      if [[ "$os_dist" = "debian" ]]; then
+         if $(echo "$os_version" | grep -q '\.') ; then
+            os_version=$(echo "$os_version" | cut --delimiter='.' -f1)
+         fi
+      fi
+
+   elif [[ -e "/etc/os-release" ]]; then
+
+      . /etc/os-release
+
+      os_dist=$ID
+      os_version=${VERSION_ID}
+
+   fi
+
+   # remove whitespace from os_dist and os_version
+   os_dist="${os_dist// /}"
+   os_version="${os_version// /}"
+
+}
+
 
 # - Is this a systemd system?
 # -
@@ -69,6 +98,13 @@ else
    systemd_exists=true
 fi
 
+# - Set variable
+# -    os_dist
+# -    os_version
+# -    os_codename
+# -
+detect_os_1
+
 echo ""
 
 
@@ -2752,10 +2788,8 @@ if $INSTALL_CLAMAV_UNOFFICIAL_SIGS ; then
       error "$(cat $tmp_err_msg)"
    fi
 
-   ## - For Debian Jessie (Debian 8)
-   ## -
-   echononl "   At directory /etc/clamav-unofficial-sigs copy os.debian8.conf to os.conf"
-   cp /etc/clamav-unofficial-sigs/os.debian8.conf /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+	echononl "   Copy readme file 'INSTALL' into '/etc/clamav-unofficial-sigs/'.."
+   cp -a /tmp/clamav-unofficial-sigs/INSTALL /etc/clamav-unofficial-sigs/INSTALL > $tmp_err_msg 2>&1
    if [[ $? -eq 0 ]] ; then
       echo_ok
    else
@@ -2763,67 +2797,91 @@ if $INSTALL_CLAMAV_UNOFFICIAL_SIGS ; then
       error "$(cat $tmp_err_msg)"
    fi
 
-   ## - Edit /etc/clamav-unofficial-sigs/os.conf and make changes if needed
-   ## -
-   ## - Maybe the following changes are needed:
-   ## -    clam_user="clamav"
-   ## -    clam_group="clamav"
-   ## -
-   ## -    clamd_pid="/var/run/clamav/clamd.pid"
-   ## -
-   ## -    clamd_restart_opt="systemctl restart clamav-daemon"
-   ## -    clamd_reload_opt="systemctl reload clamav-daemon"
-   ## - or if debian 7
-   ## -    clamd_restart_opt="service clamav-daemon restart"
-   ## -    clamd_reload_opt="service clamav-daemon reload"
-   ## -
-   ## -    clamd_socket="/var/run/clamav/clamd.ctl"
-   ## -
-   echononl "   Adjust /etc/clamav-unofficial-sigs/os.conf"
-   installation_failed=false
-   perl -i -n -p -e "s#^([ ]*\ *)(clam_user=.*)#\#\#\1\2\nclam_user=\"clamav\"#" \
-      /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-   if [[ "$?" -ne 0 ]] ; then
-      installation_failed=true
-      error "$(cat $tmp_err_msg)"
-   fi
-   perl -i -n -p -e "s#^([ ]*\ *)(clam_group=.*)#\#\#\1\2\nclam_group=\"clamav\"#" \
-      /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-   if [[ "$?" -ne 0 ]] ; then
-      installation_failed=true
-      error "$(cat $tmp_err_msg)"
-   fi
-   perl -i -n -p -e "s#^([ ]*\ *)(clamd_pid=.*)#\#\#\1\2\nclamd_pid=\"/var/run/clamav/clamd.pid\"#" \
-      /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-   if [[ "$?" -ne 0 ]] ; then
-      installation_failed=true
-      error "$(cat $tmp_err_msg)"
-   fi
+	
+	if [[ "${os_dist,,}" = "debian" ]] ; then
+		if [[ "$os_version" = "8" ]] || [[ "$os_version" = "9" ]] || [[ "$os_version" = "10" ]] ; then 
+			## - For Debian Jessie (Debian 8) // Stretch (Debian 9) // Buster (Debian 10)
+			## -
+			echononl "   At directory /etc/clamav-unofficial-sigs copy os.debian${os_version}.conf to os.conf"
+			cp /etc/clamav-unofficial-sigs/os.debian${os_version}.conf /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+			if [[ $? -eq 0 ]] ; then
+				echo_ok
+			else
+				echo_failed
+				error "$(cat $tmp_err_msg)"
+			fi
 
-   if $systemd_exists ; then
-      perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_restart_opt=.*)#\#\#\1\2\nclamd_restart_opt=\"systemctl restart clamav-daemon\"\nclamd_reload_opt=\"systemctl reload clamav-daemon\"#" \
-         /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-      if [[ "$?" -ne 0 ]] ; then
-         installation_failed=true
-         error "$(cat $tmp_err_msg)"
-      fi
-   else
-      perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_restart_opt=.*)#\#\#\1\2\nclamd_restart_opt=\"service clamav-daemon restart\"\nclamd_reload_opt=\"service clamav-daemon reload\"#" \
-         /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-      if [[ "$?" -ne 0 ]] ; then
-         installation_failed=true
-         error "$(cat $tmp_err_msg)"
-      fi
-   fi
-   perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_socket=.*)#\#\#\1\2\nclamd_socket=\"/var/run/clamav/clamd.ctl\"#" \
-      /etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
-   if [[ "$?" -ne 0 ]] ; then
-      installation_failed=true
-      error "$(cat $tmp_err_msg)"
-   fi
-   if ! $installation_failed ; then
-      echo_ok
-   fi
+			## - Edit /etc/clamav-unofficial-sigs/os.conf and make changes if needed
+			## -
+			## - Maybe the following changes are needed:
+			## -    clam_user="clamav"
+			## -    clam_group="clamav"
+			## -
+			## -    clamd_pid="/var/run/clamav/clamd.pid"
+			## -
+			## -    clamd_restart_opt="systemctl restart clamav-daemon"
+			## -    clamd_reload_opt="systemctl reload clamav-daemon"
+			## - or if debian 7
+			## -    clamd_restart_opt="service clamav-daemon restart"
+			## -    clamd_reload_opt="service clamav-daemon reload"
+			## -
+			## -    clamd_socket="/var/run/clamav/clamd.ctl"
+			## -
+			echononl "   Adjust /etc/clamav-unofficial-sigs/os.conf"
+			installation_failed=false
+			perl -i -n -p -e "s#^([ ]*\ *)(clam_user=.*)#\#\#\1\2\nclam_user=\"clamav\"#" \
+				/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+			if [[ "$?" -ne 0 ]] ; then
+				installation_failed=true
+				error "$(cat $tmp_err_msg)"
+			fi
+			perl -i -n -p -e "s#^([ ]*\ *)(clam_group=.*)#\#\#\1\2\nclam_group=\"clamav\"#" \
+				/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+			if [[ "$?" -ne 0 ]] ; then
+				installation_failed=true
+				error "$(cat $tmp_err_msg)"
+			fi
+			perl -i -n -p -e "s#^([ ]*\ *)(clamd_pid=.*)#\#\#\1\2\nclamd_pid=\"/var/run/clamav/clamd.pid\"#" \
+				/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+			if [[ "$?" -ne 0 ]] ; then
+				installation_failed=true
+				error "$(cat $tmp_err_msg)"
+			fi
+
+			if $systemd_exists ; then
+				perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_restart_opt=.*)#\#\#\1\2\nclamd_restart_opt=\"systemctl restart clamav-daemon\"\nclamd_reload_opt=\"systemctl reload clamav-daemon\"#" \
+					/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+				if [[ "$?" -ne 0 ]] ; then
+					installation_failed=true
+					error "$(cat $tmp_err_msg)"
+				fi
+			else
+				perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_restart_opt=.*)#\#\#\1\2\nclamd_restart_opt=\"service clamav-daemon restart\"\nclamd_reload_opt=\"service clamav-daemon reload\"#" \
+					/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+				if [[ "$?" -ne 0 ]] ; then
+					installation_failed=true
+					error "$(cat $tmp_err_msg)"
+				fi
+			fi
+			perl -i -n -p -e "s#^([ ]*\#?\ *)(clamd_socket=.*)#\#\#\1\2\nclamd_socket=\"/var/run/clamav/clamd.ctl\"#" \
+				/etc/clamav-unofficial-sigs/os.conf > $tmp_err_msg 2>&1
+			if [[ "$?" -ne 0 ]] ; then
+				installation_failed=true
+				error "$(cat $tmp_err_msg)"
+			fi
+			if ! $installation_failed ; then
+				echo_ok
+			fi
+		else
+			error "Cannot create file 'os.conf' (No Debian Version detected).
+                    See file /etc/clamav-unofficial-sigs/INSTALL to create it manually"
+		fi
+
+	else
+
+		error "Cannot create file 'os.conf' (No Linux Distribution detected)
+                    See file /etc/clamav-unofficial-sigs/INSTALL to create it manually"
+	fi # if [[ "${os_dist,,}" = "debian" ]]
 
    echononl "   Adjust /etc/clamav-unofficial-sigs/user.conf"