Find the oldest line in your repo

Not on Git, but I was curious and grepped through the Siemens S7 repository I maintain at work; we've been using the same comment practice since forever, with the date in ISO8601 format. (Since before ISO 8601 even was a thing!)

Oldest I found?

1986-06-17: Trygve glemte å sjekke om vi deler på null. Fikset.

(Trygve forgot to check whether we divide by zero. Fixed.)

You don't need to blame every file. Use `git rev-list` to find your oldest commit.

  git rev-list --reverse --date-order | head -1  # or
  git rev-list --reverse --author-date-order | head -1

  git ls-tree -lr <tree-ish> # where <tree-ish> is the commit ID from above.

  git show <commit-id>:/path/to/file  # you could also use `git cat-file` here

https://git-scm.com/docs/git-rev-list

https://git-scm.com/docs/git-show

https://git-scm.com/docs/git-cat-file

https://git-scm.com/docs/gitrevisions

Similar oneliner to paste on MacOS terminal and get the eldest line for each file extension:

for ext in $(git ls-files | grep -vE 'node_modules|\.git' | awk -F. '{if (NF>1) print $NF}' | sort -u); do echo -e "\n.$ext:"; git ls-files | grep "\.$ext$" | xargs -I {} git blame -w {} 2>/dev/null | LC_ALL=C sort -t'(' -k2 | head -n1; done

It's probably almost always going to be a boring config line(s) in the initial commit?

A section header in a pylintrc or Cargo.toml, a Django settings.py var, etc. Or even an import/var in a file that's core enough to still exist, import logging and LOGGER = ... for example.

I like leaving something like gitlens on so I can see the super old lines ad-hoc when I naturally come across them. It's fun to get glimpses of the past.

In our monorepo (of 101470 Java files, according to

    find . -name '*.java' | wc -l

Our code base still has ghost comments about code being just so because the NeXT compiler won't accept it any other way. No one has the heart to remove them.

Not sure why all the lines of code. This is much shorter:

    git ls-files|xargs -n 1 git blame --date=format:%Y%m%d -f |grep -Eo '\d{8}.*' |sort -r | head -n 1 | sed 's/^[^)]*) \t//'

"Initial Commit", 9 years ago (transfered an at-the-time 15 year old SVN repo)

sigh..

doesn't seem to work on macOS, I get:

  find: illegal option -- t
  usage: find [-H | -L | -P] [-EXdsx] [-f path] path ... [expression]
         find [-H | -L | -P] [-EXdsx] -f path [path ...] [expression]

At my old job, I remember it was some time at the beginning of the 1990s. I was born like 8 years after the code I was working on was written.

> README.md 2021-01-28 17:27:57 +1100

Huh, TIL the birthdate of my business was actually a couple of days ago.