Add verify format

.github/workflows/verify-fmt.yml

@@ -0,0 +1,17 @@
+name: Verify Format
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  Patch:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Verify domain.txt
+        run: |
+          ./hack/verify-fmt.sh domain.txt || { echo "Please run './hack/fmt.sh domain.txt'"; exit 1; }
+      - name: Verify mirror.txt
+        run: |
+          ./hack/verify-fmt.sh mirror.txt || { echo "Please run './hack/fmt.sh mirror.txt'"; exit 1; }

hack/fmt.sh

@@ -1,3 +1,3 @@
 #!/usr/bin/env bash
 
-cat $1 | sort | tac > $1.tmp && mv $1.tmp $1
+cat $1 | sort -u | grep -v '^$' > $1.tmp && mv $1.tmp $1

hack/verify-fmt.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+cp $1 $1.bak
+./hack/fmt.sh $1
+
+diff -c $1 $1.bak
+rm $1.bak