update: add GRUB warning for matter-iso

README.md

@@ -10,7 +10,7 @@ Following dependencies are required for these scripts and tools:
 - coreutils
 - gcc
 - make
-- GRUB
+- GRUB (please see matter-iso warning)
 - gnupg
 - fakeroot
 - (GNU) tar

matter-iso/main.sh

@@ -75,6 +75,14 @@ check_iso_vars() {
 #################
 ## main script ##
 #################
+if ! type "grub-mkrescue" > /dev/null; then
+  error "You need to install GRUB to create ISO files with grub-mkrescue"
+  set_indent
+  info "If you want to create UEFI ISO files make sure you install x64 GRUB or grub-efi"
+  info "If you want to create BIOS ISO files make sure you install x86 GRUB or grub-bios"
+  exit 1
+fi
+
 if [ "$EUID" -ne 0 ]; then
   error "You should run this script as root"
   exit 1