Makefile rule for Jekyll drafts

I’ve previously written about my fondness for Makefiles, so it feels on brand that I continue talking about it.

My latest idea was to leverage these files for blogging. Jekyll posts follow a simple YEAR-MONTH-DAY-title.MARKUP format, which seemed perfect to be automated. In an ideal world, I would like to just start writing and my computer to figure out these details.

Since I had previously outsourced some Jekyll development commands to my own Makefile (you can check the source code here), I guessed this could be another one. I’ll leave you with my final result for now and I’ll explain it afterwords:

FILENAME:=./_drafts/$(shell date +'%Y-%m-%d')-.md
define post
---
title: ''
date: $(shell date +'%Y-%m-%d') 00:00:00
tags:
layout: post
---
endef
export post
draft:
  touch $(FILENAME)
  echo "$$post" > $(FILENAME)

If you put this on a Makefile and run make draft, this is what you get:

goncalomorais@amadeus:~/D/g/_/blog|gh-pages✓
➤ make draft
touch ./_drafts/2020-03-08-.md
echo "$post" > ./_drafts/2020-03-08-.md

Let’s see what does this create:

goncalomorais@amadeus:~/D/g/_/blog|gh-pages⚡?
➤ git status
On branch gh-pages
Your branch is ahead of 'origin/gh-pages' by 1 commit.
  (use "git push" to publish your local commits)

Untracked files:
  (use "git add <file>..." to include in what will be committed)
  _drafts/2020-03-08-.md

nothing added to commit but untracked files present (use "git add" to track)

goncalomorais@amadeus:~/D/g/_/blog|gh-pages⚡?
➤ cat _drafts/2020-03-08-.md
---
title: ''
date: 2020-03-08 00:00:00
tags:
layout: post
---

What does this all mean, though? Let’s break it down bit by bit to have a better understanding of why we need them.

---

FILENAME:=./_drafts/$(shell date +'%Y-%m-%d')-.md

The line above allows us to generate a file with the format YYYY-MM-DD-.md on the _drafts folder and save it on a make variable (not a regular shell variable), which a kind soul on StackOverflow made at point to differentiate.

define post
---
title: ''
date: $(shell date +'%Y-%m-%d') 00:00:00
tags:
layout: post
---
endef
export post

Next, we’re using a nice way to define a multiline string on Makefiles, which allows us to store it on a variable so we can later insert it on the draft file we just created.

draft:
  touch $(FILENAME)
  echo "$$post" > $(FILENAME)

Finally, the bow that wraps everything nicely. The rule draft now runs two simple commands:

• touch sets the modification and access times of files, but if any file does not exist, it gets created;
• echo technically display a line of text, but the > operator is redirecting the output to the new file we just created, filling it in with the Jekyll post header.

That’s it, we’re now able to run make draft and quickly create a draft file for today’s blog entry. This post was created like that!