3 ms·

Ask HN: How to Do This in Git

2 points by pm2222 4y ago

Suppose I'm writing a tutorial and as a simple example there's only one source file. Incremental changes will be made to this file step by step along the way. So far I this have commit history: commit1-commit2-commit3-...-commit100-(Head) commit1: This is step1 commit2: This is step1 This is step3 commit3: This is step1 This is step3 This is step3 .. Commit100: I wish to be able to tell readers to go to commitX for source file of stepX. Now obviously in commit2 there's a typo and it's inherited by commit3 and so on. What's the best way to achieve my goal, is it a natural thing for git to do?

cratermoon 4y ago
Branch at commit1, make a new commit2, commit2a, then rebase commit3 onto commit2a
fargle 4y ago
interactive rebase can do this: git rebase -i commit1 it will open an editor. find commit2 in the text file and change "pick" to "edit". save&exit editor it will dump you out on commit2 (with the typo). use an editor to fix the typo in typofile. then: git add typofile git commit --amend git rebase --continue then it will rebase the other 99 commits on top, if there are any conflicts it will stop and you'll have to fix them. you can optionally skip the git commit --amend right after git add and rebase --continue does it automatically anyway.
- pm2222 4y ago
  Since the typo is inherited in commit3+, conflict is guaranteed after commit2 is amended, right? Is there a way to automate this? I do appreciate the clean commit history with this approach.
  - fargle 4y ago
    No, if the lines around the change are stable, it should resolve itself. Assuming that after line commit3 was edited, the future changes occur further down in the file, (which is usual). At worst, it should be OK after a conflict or two. NOTE: also this is just a different way of performing the same thing as the other rebase suggestion. It's also the same as cherry-picking each newer commit manually. All methods will have the same amount of conflict resolution. UPDATE: I just constructed this exact scenario to test it and can confirm that if your sequence is exactly as described, you'll get one conflict commit #3 after you edit commit #2. After it's resolved, the other 98 commits are automatic.
    - pm2222 4y ago
      Great it works just as you describe. I notice that the commit hashes change except commit1. Would tag be stable with rebase operation and can be used in my case? Perhaps it's too much to ask git.

2 points by pm2222 4y ago

cratermoon 4y ago

Branch at commit1, make a new commit2, commit2a, then rebase commit3 onto commit2a

fargle 4y ago

interactive rebase can do this: git rebase -i commit1 it will open an editor. find commit2 in the text file and change "pick" to "edit". save&exit editor it will dump you out on commit2 (with the typo). use an editor to fix the typo in typofile. then: git add typofile git commit --amend git rebase --continue then it will rebase the other 99 commits on top, if there are any conflicts it will stop and you'll have to fix them. you can optionally skip the git commit --amend right after git add and rebase --continue does it automatically anyway.

pm2222 4y ago
Since the typo is inherited in commit3+, conflict is guaranteed after commit2 is amended, right? Is there a way to automate this? I do appreciate the clean commit history with this approach.
- fargle 4y ago
  No, if the lines around the change are stable, it should resolve itself. Assuming that after line commit3 was edited, the future changes occur further down in the file, (which is usual). At worst, it should be OK after a conflict or two. NOTE: also this is just a different way of performing the same thing as the other rebase suggestion. It's also the same as cherry-picking each newer commit manually. All methods will have the same amount of conflict resolution. UPDATE: I just constructed this exact scenario to test it and can confirm that if your sequence is exactly as described, you'll get one conflict commit #3 after you edit commit #2. After it's resolved, the other 98 commits are automatic.
  - pm2222 4y ago
    Great it works just as you describe. I notice that the commit hashes change except commit1. Would tag be stable with rebase operation and can be used in my case? Perhaps it's too much to ask git.