make-new-post.rb

#!/usr/bin/ruby

if ARGV.empty?
  puts "Usage: ruby make-new-post.rb SLUG"
  exit
end

POST_DIR = "/PATH/TO/YOUR/DEAL" # no trailing slash

date = Time.now.strftime("%Y-%m-%d")
slug = ARGV[0]

# the layout/category/permalink values are, of course, specific to my setup

new_file = <<MONKEYTIME
---
layout: note
category: note
date: #{date}
title: TITLE_HERE
permalink: note/#{slug}
---
Put your markdown here, dude
MONKEYTIME

filename = "#{POST_DIR}/#{date}-#{slug}.md"

if !File.exist?(filename) then
  File.open(filename, "w") { |file| file.write(new_file) }
  # i think iA Writer is nearly perfect for this but obv you can substitute something else
  spawn "open -a iA\\ Writer #{filename}"
  puts "Made #{filename}, opened it in iA Writer"
else
  puts "Error: that post already exists."
end

# optionally, put this in your .profile:
# newpostfunction() {
#    ruby /PATH/TO/FILE/make-new-post.rb $1
# }
# alias newpost=newpostfunction