A quick script I used to convert my Red Notebook data files to plain Markdown (needs changes to apply elsewhere)

journalizer.js

#!/usr/bin/node

const Promise = require('bluebird');
const fs = Promise.promisifyAll(require('fs'));
const moment = require('moment');
const YAML = require('yamljs');

let today = moment();

function readJournal(dir, date) {
	return fs.readFileAsync(dir + '/' + date.format('YYYY-MM') + '.txt', 'utf8')
	.catch(()=>null)
	.then(d=>{
		if (!d) return d;
		try { return YAML.parse(d)[date.format('D')]; }
		catch(ex) { return null; }
	});
}

// Change start date to an approparite date
for (let d = moment([2013, 1, 1]); d.isBefore(today); d.add(1, 'day')) {
	let date = d.clone();
	Promise.all([
		Promise.resolve(date),
		// Put the folder names of your journals here
		readJournal('data', date),
		readJournal('dream-journal', date)
	]).then(a=>{
	  // Modify to join them into one file how you like
		let date = a[0];
		let data = a[1];
		let dream = a[2];
		let content = '\n';
		if (data) {
			content += '# Journal\n\n' + data.text;
		}
		if (dream) {
			content += '# Dream Journal\n\n' + dream.text;
		}
		if (content == '\n') return;
		a[0] = date.toString();
		fs.writeFile('out/journal-' + date.format('YYYY-MM-DD') + '.md', content);
	});
}