...

makefile

@@ -1,5 +1,8 @@
+BUILDDIR=mkdir-build
 CC = i386-elf-gcc -ffreestanding -m32
 
+iso: .build/ .build/nub-os.iso
+
 .build/nub-os.iso: .build/kernel.bin
 	mkdir -p .build/iso/boot/grub
 	cp grub.cfg .build/iso/boot/grub
@@ -24,5 +27,8 @@ CC = i386-elf-gcc -ffreestanding -m32
 run: .build/nub-os.iso
 	qemu-system-x86_64 -cdrom .build/nub-os.iso
 
+.build/:
+	mkdir .build
+
 clean:
-	@rm -r .build/* 2>/dev/null || true
+	@rm -r .build 2>/dev/null || true