Garrick Aden-Buie - Add last rendered or modified time to Quarto

An AI-generated pencil-drawn sketch of a dream sequence. A spiral staircase descends into a clock face, surrounded by planets, clouds and stars.

A blog is a perpetual side-project machine

They say that if you copy-paste the same code three times, write a function. I’ve also heard that if you send the same email more than once, turn that email into a blog post.

But all the real work in life happens on Slack. So if a friend asks for your advice and you brain dump everything you know about the easiest way to install and manage Python, then you’ve got a first draft blog post on your hands!

They also say the hardest part of writing is staring at the blank page. But they are wrong. The hardest part of writing is figuring out how to start a new .qmd file in your blog repo without bumping into 3 to 10 other things you have been meaning to do.

Or worse, you might encounter that draft post you’ve been working on for months. Learn from my mistakes: it’s okay to stash that post, you can always tell yourself you’ll come back to it later!

You can probably tell by now that this is not a post about Python tooling for a happy setup. It’s also not a post about the few CSS tweaks I made while trying to open up this editor.

This post is sponsored by this a bit of YAML that caught my eye in my _quarto.yml file in the split second before I closed all my open tabs.

page-footer:
    left: >-
      © 2023 Garrick Aden-Buie

Now the fix could be easy. Consider this: I could change that file, commit it, and push it.

page-footer:
  left: >-
-    © 2023 Garrick Aden-Buie
+    © 2024 Garrick Aden-Buie

One GitHub Action, several minutes, and two Netlify notifications later my blog would be back to the future.

But this obviously won’t work. Time stops for no one. What will I do in March of 2025? Come back to this file and edit it by hand? Again? Like a caveman? Hard no.

Wouldn’t it be awesome if I could replace that 2023 that should be 2024 with something that turns into the current year whenever my blog rebuilds? I could save minutes in the entire lifetime of my blog! Imagine replacing the 2023 with something that would update itself automatically, like this:

page-footer:
  left: >-
    © {{< now year >}} Garrick Aden-Buie

It would be awesome, but that syntax doesn’t exist in Quarto. Or it didn’t until I my productive procrastination instincts kicked in!

Introducing now, a quarto extension for easily adding the time right now – err… the time right now when your Quarto blog or document is rendered.

Hello, now

To start using now in your own Quarto projects, just install the extension with this command.

quarto add gadenbuie/quarto-now

You can read all about the extension on its (quarto-built) page here: pkg.garrickadenbuie.com/quarto-now. Or keep reading this post for a quick intro.

Using now

now, the extension, comes with two shortcodes you can use just about anywhere: {{< now >}} and {{< modified >}}. Both work in the same way, except that {{< modified >}} will show the last modified time of the document, either by using the modified metadata field or the last modified timestamp of the file (on macOS and Linux only, sorry).

Here’s a quick example of the shortcodes in use. Note that in this post I added the modified date, which gives me a bit more control over what counts as a “modification”.

---
title: Add last rendered or modified time to Quarto
modified: 2024-03-29
---

This document was last modified at {{< modified >}}
and it was last rendered at {{< now >}}.

This document was last modified at 2024-03-29 00:00:00 and it was last rendered at 2024-04-20 14:31:47.

Formatting the time output

By default, now uses ISO 8601 (ish) formatting, but that’s not usually the most human-readable format. now comes with a few built-in aliases for common date and time parts.

Shortcode	Result	Format String
`{{< now >}}`	2024-04-20 14:31:47	`"%F %T"`
`{{< now year >}}`	2024	`"%Y"`
`{{< now month >}}`	April	`"%B"`
`{{< now day >}}`	20	`"%d"`
`{{< now weekday >}}`	Saturday	`"%A"`
`{{< now hour >}}`	02	`"%I"`
`{{< now minute >}}`	31	`"%M"`
`{{< now ampm >}}`	PM	`"%p"`
`{{< now date >}}`	04/20/24	`"%x"`
`{{< now time >}}`	14:31:47	`"%X"`
`{{< now datetime >}}`	Sat Apr 20 14:31:47 2024	`"%c"`
`{{< now isodate >}}`	2024-04-20	`"%F"`
`{{< now isotime >}}`	14:31:47	`"%T"`
`{{< now isodatetime >}}`	2024-04-20T14:31:47-0400	`"%FT%T%z"`
`{{< now timestamp >}}`	2024-04-20 14:31:47	`"%F %T"`

Note that the shortcodes only accept a single format argument, so you’d need to write {{< modified month >}} {{< modified year >}} instead of {{< modified month year >}}.

That said, you can always use the format strings supported by Lua’s os.date() function, so {{< modified "%B %Y" >}} gives you the month and year: March 2024. Note that because the format string has a space, it needs to be quoted "%B %Y".

You can find the complete list of accepted format strings in the now extension docs.

Have a good day, meow!

This was a fun excursion into the world of Quarto extensions! Thanks for reading and I hope you find now useful in your own projects. May you benefit from my inability to do the thing I’m “supposed to do” (hey, it’s my free time!).

The feature image was generated with DALL-E 3 and the following prompt: an m.c. escher style pencil sketch of a dreamy clock face.