Fix path substitution and iteration in makefile example

Author: maciejzj

README.md

@@ -114,24 +114,28 @@ way:
 
 ```makefile
 markdown_pages := index.md
+
 posts_dir := posts
+output_dir := docs
 
 markdown_posts := $(wildcard $(posts_dir)/*.md)
 
 # Main markdown pages
-generated_files := $(markdown_pages:%.md=%.html)
+generated_files := $(foreach page,$(markdown_pages),$(patsubst %.md,$(output_dir)/%.html,$(page)))
 # Append posts pages
-generated_files += $(patsubst $(posts_dir)/%.md,%.html,$(markdown_posts))
+generated_files += $(foreach post,$(markdown_posts),$(patsubst $(posts_dir)/%.md,$(output_dir)/%.html,$(post)))
 
 .DEFAULT: compile
 
-compile: $(markdown_pages) $(markdown_posts)
-	../ssb/ssb -p $(posts_dir) $(markdown_pages)
+compile: $(generated_files)
+
+$(generated_files): $(markdown_pages) $(markdown_posts)
+	ssb -p $(posts_dir) -o $(output_dir) $(markdown_pages)
 
 .PHONY: clean
 
 clean:
-	rm $(generated_files)
+	rm -f $(generated_files)
 ```
 
 ## Acknowledgements