/geek

And I want my last words to be if I die from it…”it was delicious”

Fuck you, Dark Souls.

(┛◉Д◉)┛彡┻━┻

Recently, I needed to do some repository splitting using git. Originally, I figured this would be a long and laborious process that I would curse for years to come. So let me start this off with this: It wasn’t that bad.

I googled quite a bit and found this fantastic StackOverflow post about it. I needed to do something a little different than what was done here so I’ll walk you guys through the whole process.

So let’s say you have a git repository laid out as follows:

 proj1/
    best_app_ever.php
    tests/
    old_project/
    ABC/
    ABC.php

Let’s say you want to move the directory ABC and ABC.php from the project above because proj1 has just become too big and place it into a new project called proj2.

Step 1: Clone your repository as proj2

git clone proj1 proj2

Optional: Remove your origin. I do this just so I don’t accidentally remove anything from the origin.

git remote rm origin

Step 2: Filter the history out you don’t want.

git filter-branch --index-filter "git rm -rf best_app_ever.php tests old_project" --prune-empty -- --all

Here is where I start to diverge from the StackOverflow post, I don’t want to just extract out ABC, I want ABC.php as well. Using —subdirectory-filter just won’t cut it here. We use index-filter to rewrite the index and run the command git remove command on the files I don’t want. The prune-empty flag will trim the commits that are empty that occurred while executing your filter. It’s important to note that —all will rewrite all branches and tags.

Step 3: Reset the index and working tree

git reset --hard

Step 4: Clean up all your refs

git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d

This goes through all the refs and deletes them if they contain an old value.

Step 5: Expire all the old reflog entries

git reflog expire --expire=now --all

Step 6: Clean up and optimize, pruning anything older than now.

git gc --aggressive --prune=now

The above steps should create two different repositories with all history preserved!

proj1/
    best_app_ever.php
    tests/
    old_project/

proj2/
     ABC/
     ABC.php

Hope this helps you the next time you need to split up a repository!

Recently, I wanted to see what files in a commit changed over here at Tumblr so that we could do some syntax checking.

So I needed to basically see all the files that changed on a merge commit that happened with 2 parents. The following command pulls out all the php files from that merge commit.

git show --pretty="format:" --name-only parent1...parent2 | grep .php | sort | uniq

With this one liner, I have a list of all the different files that changed in the commit, ready to be lint checked. Neat, huh? Git is awesome.

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