From fb0ad9b1079878d9012334e447a1e7ef7502feae Mon Sep 17 00:00:00 2001
From: Jakub Jirutka <jakub@jirutka.cz>
Date: Wed, 11 Oct 2017 20:23:29 +0200
Subject: [PATCH] Fix error when cleanup is called before nbd_dev is set

---
 alpine-make-vm-image | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/alpine-make-vm-image b/alpine-make-vm-image
index 3a0d154..adf678b 100755
--- a/alpine-make-vm-image
+++ b/alpine-make-vm-image
@@ -117,9 +117,10 @@ cleanup() {
 			|| die "Failed to unmount $mount_dir; unmount it and disconnect $nbd_dev manually"
 		rm -Rf "$mount_dir" || :
 	fi
-	qemu-nbd --disconnect "$nbd_dev" \
-		|| die "Failed to disconnect $nbd_dev; disconnect it manually"
-
+	if [ -n "$nbd_dev" ]; then
+		qemu-nbd --disconnect "$nbd_dev" \
+			|| die "Failed to disconnect $nbd_dev; disconnect it manually"
+	fi
 	if [ "$INSTALL_HOST_PKGS" = yes ]; then
 		_apk del $VIRTUAL_PKG
 	fi