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Orici
Asked: 2020-10-13 03:35:38 +0800 CST 2020-10-13 03:35:38 +0800 CST

Can I create a new Git branch from a previous "commit"?

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I'm doing some regression testing looking for a bug I introduced in a project, basically cloning the current repository, removing x commits and testing to see where the bug appeared... I wanted to explore other alternatives.

The usual thing is to create new branches from the current moment of work in the repository and at this moment I wish I had created a new branch x commits ago... Since I didn't, I would like to know if it is possible to create a new branch from a given commit , for example from 4 commits ago... any way to do it?

git

2 Answers

  1. Although Nicolas' answer directly answers your question, since you are looking for alternative ways to isolate the commit that introduced a defect to your project, I suggest you investigate using git bisect .

    git bisectit is precisely designed to optimally retrieve (using binary search) the commit that introduced a problem.

    For it to work properly, you must provide 2 initial reference points:

    1. a known commit includes the defect (probably the current commit)
    2. a commit that definitely does not include the defect

    For example, let's say you know that your current branch has the problem. And although you don't know in which precise commit the problem appeared, you are sure that 100 commits ago (say) the problem didn't exist. Then you would start the investigation as follows:

    git bisect start
git bisect bad
git bisect good abc123def456

    ... where git bisect badit indicates that the current commit has the problem, and git bisect good abc123def456it indicates that you are at least sure that the problem did not exist in the commit abc123def456.

    With this information in hand, git now automatically chooses (using the binary search algorithm) a commit to checkout.

    Now it's your turn to test that commit to see if the defect exists or not. If the chosen commit has the defect, then you must indicate it with the command:

    git bisect bad

    But if the commit does not have the defect, then you must indicate it with:

    git bisect good

    Depending on what you reply, git now automatically picks another commit to checkout. And again, you have to test this commit to see if the defect is present or not, and you must indicate it with git bisect bador git bisect good.

    This process continues successively (and binary to minimize the number of commits you need to examine) until eventually git tells you which commit is guilty of introducing the defect.

    Finally, once the investigation is over, you end up with:

    git bisect reset

    ...and this returns you to your initial state before you started the git bisect.

    • 8
  2. Best Answer

    You can use this option:

    git branch <nombre-rama> <sha1-commit>

    It is also valid to use symbolic references, but I use this option on a daily basis, it seems simpler and more flexible to me.

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