Checkdoc batch mode

Makefile

@@ -1,7 +1,6 @@
 SHELL = bash
 EMACS ?= emacs
 PORT ?= 8000
-NOOUTPUT = grep -v '^Loading' | { ! grep '^'; }
 PACKAGES = packages
 FONT_SIZE ?= 180
 ENV ?= env
@@ -68,12 +67,11 @@ lint-file:
 	@printf "\n--> Step: Byte-compile file\n\n"
 	$(EMACS) --batch -L . \
 			 --eval "(setq byte-compile-error-on-warn t)" \
-			 -f batch-byte-compile "$(filename)" 2>&1
+			 -f batch-byte-compile "$(filename)"
 	@printf "\n--> Step: Run checkdoc\n\n"
 	yes n | $(EMACS) --batch \
-			 --eval '(find-file "$(filename)")' \
-			 --eval '(setq sentence-end-double-space nil)' \
-			 --eval '(checkdoc-current-buffer)' 2>&1 | $(NOOUTPUT)
+             -l test/checkdoc-batch.el \
+			 -f checkdoc-batch-and-exit "$(filename)"
 	@printf "\n--> Step: Run package-lint\n\n"
 	$(EMACS) --batch --eval "(setq package-user-dir \"$$PWD/$(PACKAGES)\")" \
 			 --eval "(package-initialize)" \

test/checkdoc-batch.el

@@ -0,0 +1,28 @@
+;; checkdoc-batch.el --- Batch mode for checkdoc  -*- lexical-binding: t; -*-
+
+(defun checkdoc-batch-and-exit ()
+  "Run checkdoc in batch mode for a set of files.
+Exit with 1 if one or more warnings were emitted, otherwise with 0."
+  (unless noninteractive
+    (error "`checkdoc-batch-and-exit' is to be used only with -batch"))
+  (let ((status 0)
+        path)
+    (while command-line-args-left
+      (setq path (car command-line-args-left))
+      (with-current-buffer (find-file-noselect path)
+        (checkdoc-current-buffer t))
+      (with-current-buffer "*Style Warnings*"
+        (goto-char (point-min))
+        (while (not (eobp))
+          (let* ((rule "[ \t\n\r\f]+")
+                 (line (string-trim (buffer-substring-no-properties
+                                     (line-beginning-position)
+                                     (line-end-position))
+                                    rule rule)))
+            (when (and (not (string= line ""))
+                       (not (string-prefix-p "*" line)))
+              (princ (concat line "\n"))
+              (setq status 1)))
+          (ignore-errors (next-line))))
+      (setq command-line-args-left (cdr command-line-args-left)))
+    (kill-emacs status)))