From 2943e9dc8d9b49fb18856b4ba050c40df1d42aed Mon Sep 17 00:00:00 2001
From: zstadler <zeev.stadler@gmail.com>
Date: Tue, 16 Mar 2021 18:20:25 +0200
Subject: [PATCH] Avoid grep errors in `clean-unnecessary-docker` (#1089)

When `make clean-unnecessary-docker` is run twice, or when there are no docker images tagges as "<none>", make fails because grep fails:

```
Deleting unnecessary container(s)...
Deleting unnecessary image(s)...
make: *** [Makefile:562: clean-unnecessary-docker] Error 1
```

Using `awk` to _also_ search for "<none>", instead of `grep`, solves this issue.
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 96eb583c..f51c9630 100644
--- a/Makefile
+++ b/Makefile
@@ -559,7 +559,7 @@ clean-unnecessary-docker:
 	@echo "Deleting unnecessary container(s)..."
 	@docker ps -a -q --filter "status=exited" | $(XARGS) docker rm
 	@echo "Deleting unnecessary image(s)..."
-	@docker images | grep \<none\> | awk -F" " '{print $$3}' | $(XARGS) docker rmi
+	@docker images | awk -F" " '/<none>/{print $$3}' | $(XARGS) docker rmi
 
 .PHONY: test-perf-null
 test-perf-null: init-dirs