Use install for certificate file permissions and ownership

Replace separate cp and chmod/chown operations with single install
commands
for certificate, key, and PEM files to simplify permission handling

certman.sh

@@ -176,33 +176,20 @@ install_certificate() {
 
     # Install new certificate and key
     if [ $needs_reload -eq 1 ]; then
-        if ! cp -f "$temp_cert" "$final_cert" || ! cp -f "$temp_key" "$final_key"; then
-            echo -e "${RED}Failed to install certificate files for $domain${NC}"
+        if ! install -m "$CERT_PERMISSIONS" -o "$CERT_OWNER" -g "$CERT_GROUP" "$temp_cert" "$final_cert"; then
+            echo -e "${RED}Failed to install certificate for $domain${NC}"
             return 1
         fi
-
-        # Set permissions and ownership for cert and key separately
-        if ! chown "$CERT_OWNER:$CERT_GROUP" "$final_cert" || \
-           ! chmod "$CERT_PERMISSIONS" "$final_cert"; then
-            echo -e "${RED}Failed to set permissions for $final_cert${NC}"
-            return 1
-        fi
-        if ! chown "$CERT_OWNER:$CERT_GROUP" "$final_key" || \
-           ! chmod "$KEY_PERMISSIONS" "$final_key"; then
-            echo -e "${RED}Failed to set permissions for $final_key${NC}"
+        if ! install -m "$KEY_PERMISSIONS" -o "$CERT_OWNER" -g "$CERT_GROUP" "$temp_key" "$final_key"; then
+            echo -e "${RED}Failed to install private key for $domain${NC}"
             return 1
         fi
 
         if [ "$FULLCHAIN_PEM" = "true" ]; then
-            if ! cp -f "$temp_pem" "$final_pem"; then
+            if ! install -m "$KEY_PERMISSIONS" -o "$CERT_OWNER" -g "$CERT_GROUP" "$temp_pem" "$final_pem"; then
                 echo -e "${RED}Failed to install PEM file for $domain${NC}"
                 return 1
             fi
-            if ! chown "$CERT_OWNER:$CERT_GROUP" "$final_pem" || \
-               ! chmod "$KEY_PERMISSIONS" "$final_pem"; then
-                echo -e "${RED}Failed to set permissions for $final_pem${NC}"
-                return 1
-            fi
         fi
 
         echo -e "${GREEN}Certificate updated for $domain${NC}"