A liquid tag for Jekyll to indicate the last time a file was modified.

This plugin determines a page's last modified date by checking the last Git commit date of source files. In the event Git is not available, the file's mtime is used.

Open your Gemfile in your Jekyll root folder and add the following:

group :jekyll_plugins do
  gem "jekyll-last-modified-at"
end

Add the following to your site's _config.yml file

plugins:
  - jekyll-last-modified-at

# Optional. The default date format, used if none is specified in the tag.
last-modified-at:
    date-format: '%d-%b-%y'

There are a few ways to use this gem.

You can place the following tag somewhere within your layout:

{% last_modified_at %}

By default, this creates a time format matching "%d-%b-%y" (like "04-Jan-14").

You can also choose to pass along your own time format. For example:

{% last_modified_at %Y:%B:%A:%d:%S:%R %}

That produces "2014:January:Saturday:04."

You can also call the method directly on a Jekyll "object," like so:

{{ page.last_modified_at }}

To format such a time, you'll need to rely on Liquid's date filter:

{{ page.last_modified_at | date: '%Y:%B:%A:%d:%S:%R' }}

(It's generally more performant to use the page.last_modified_at version of this plugin.)