Show modification time on GoHugo posts

I want to be able to show the last time I updated the content of a file, but I don’t want anything fancy in charge of doing so. I want something simple and easy. Something I won’t need much time to maintain or modify as I please with no fuzz. Here I show you how I accomplish this by use the front matter to manually specify the updated time of any post.

The first thing we will need is to create a template for any post under layout/_default/single.html. It’s content should be something similar to what’s on snippet below; it defines that the custom changes belong to the main area, adds the title as a header, and also add the original publication date of the post. Note the Updated on will be displayed only in case the last modification (Lastmod) is different than the publication date (Date).

 1{{ define "main" }}
 2  <article>
 3    <h1>{{ .Title }}</h1>
 4    <div style="margin-bottom:0.5em; color:#888; font-size:0.95em;">
 5      Published on {{ .Date.Format "2006-01-02" }}
 6      {{ if ne .Lastmod.Unix .Date.Unix }}
 7      | Updated on {{ .Lastmod.Format "2006-01-02" }}
 8      {{ end }}
 9    </div>
10    {{ .Content }}
11  </article>
12{{ end }}

To set the last modification date of a post you will need to add the lastmod method in the front matter. For example, here I have the front matter for the TIL GoHugo callouts. I add the date: 2025-0615... and the lastmod: 2025-06-19....

 1---
 2title: GoHugo callouts
 3date: 2025-06-15T23:02:20Z
 4lastmod: 2025-06-19T21:00:00Z
 5draft: false
 6tags:
 7- hugo
 8- go-hugo
 9- callouts
10---

By doing so, the page renders both published and updated on dates as shown in the screenshot below. With this, we are now able to show to people whether or not a page has been updated or if its been untouched for years.