Today I wanted to know the birthday of my blog. I knew I've started it early 2024 but I wasn't sure anymore. Looking at the first blog post would have been a solution, but I figured I would ask in natural language in Warp.

The first attempt gave me the first commit:

$ git log --reverse --oneline | head -1
34b1bc8 initialize Pelican blog setup

The key here is the smart combination of --reverse, --oneline and the pipe to head 1.

• --reverse tells git log to start from the first commit
• --oneline allows to simplify each commit record to a single line, without details. It is a shorthand for --pretty=oneline --abbrev-commit used together.
• the pipe to head 1 cuts the output of git log to the first line, which is the oldest commit record.

Nice. But it didn't give me a date! Second attempt gave me my answer.

$ git --no-pager log --reverse --format="%ad %h %s" --date=format:"%Y-%m-%d %H:%M:%S" | head -1
2024-02-22 14:12:20 34b1bc8 initialize Pelican blog setup

Here same approach with --reverse and head 1 but a few extra options are passed:

• --no-pager will only show as many lines as your terminal can show, and will not allow you to see more, as you usually by hitting Space.

• --format allows you to specify an output format, less known and a level deeper in the git documentation.

  • %ad is the author date (and it respects --date= option)
  • %h is for the abbreviated commit hash
  • %s is the subject, i.e. the commit message

• --date=format makes it possible to specify the date time format for the date field.

You can also play with the date format and ask for a "relative" date:

$ git --no-pager log --reverse --format="%ad %h %s" --date=relative | head -1
1 year, 4 months ago 34b1bc8 initialize Pelican blog setup

Git is an extremely powerful tool with a quasi-endless list of command-line options, and it's proven again with git log.

And this blog is 1 year and 4 months old 😊!

Sources: Git log commit formatting