bliki & updating Jekyll post dates Edit article View article history

In case you decided to run your bliki[1] using Jekyll[2], consider using a Git[3] pre-commit hook[4] to update the date entries in the front matter of your posts. E.g. you want to modify the following front matter

layout: post
title: bliki & updating Jekyll post dates
tags: [bliki, Jekyll, dates, Git, hooks]
date: 2016-03-28

by updating its date entry with the current date to get

layout: post
title: bliki & updating Jekyll post dates
tags: [bliki, Jekyll, dates, Git, hooks]
date: 2016-04-02

on each commit to the Git repository that contains your Jekyll sources. In order to automate this process, follow these steps:

  1. Create a file called pre-commmit inside the .git/hooks directory of your repository

    • touch .git/hooks/pre-commit

  2. Mark it as executable

    • chmod +x .git/hooks/pre-commit

  3. Place the following code in it:


# pattern for any ISO8601 compatible date pattern
# pattern for any date in the front matter of a post
any_date="date\: $iso_date"

# Current date in ISO8601
now=`date +%Y-%m-%d`
# today's replacement for the above pattern
today="date\: $now"

# start- and end-delimiters of a post front matter

# project relative paths
modified_files=`git diff --name-only HEAD`

for file in $modified_files; do
    # only modify Jekyll posts
    if [[ $file == _posts/*.asciidoc ]]; then
        # extract current post date from front matter (first match)
        post_date=`grep -m 1 -o "$any_date" "$file" | head -1 | grep -o "$iso_date"`

        # only modify posts that are not up-to-date yet
        if [[ $post_date != $today ]]; then
            # update the front matter of the post with today's date
            sed -i -e "/$front_matter/,/$front_matter/s/$any_date/$today/" "$file"
            # add the updated file to the git index so it becomes part of the current commit
            git add "$file"
This hook only works on posts that have a date entry in their front matter.
OSX users have to replace the sed call with: sed -i -e "s/$any_date/$today/1" "$file" [5]

Once these steps are completed, every committed update to a post will set its date entry to the current date. The file modification will not trigger another commit, instead the change will be part of the soon-to-be-commit that triggered the pre-commit hook.

Others came up with similar[6] solutions.