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gitgit-filter-branch

What happened to the changes that I made using git filter-branch?

For the first time, I tried to rewrite my git history using git filter-branch. I did this by writing a (Python) script (let's call it edit_file) that makes an edit to a file (let's call it target_file). Then, I ran this command:

git filter-branch --tree-filter "path/to/edit_file" HEAD

I got a nice stream of output which seemed to indicate that I'd gotten the effect that I wanted, but when viewed target_file, I did not see any changes. When I run edit_file directly, target_file in my working copy successfully receives the edits that I intended.

It sounds like my changes exist within some deep, dark, and dank recess in git's twisted mind, and I just need a magical incantation to summon forth my changes. I have no idea whether this is correct, nor do I understand where to begin looking, because all the material that I've read (including the official git book) indicates that once git filter-branch finishes, the branch that I am working on should have the changes that edit_file would perform on every version of target_file...

Halp?

Sorry if this is a bit long winded, but I don't know what details are necessary (because that is a core feature of being confused).

More details:

The reasons I say that it looked like filter-branch did what I wanted are:

  1. I could see the output of edit_file running on each commit, and it indicated success on all of them. The output of edit_file changes as it operates on different versions of target_file, and I was able to see the different output from edit_file as git filter-branch moved through history.

  2. At the end, I saw this:

    Ref 'refs/heads/my-branch' was rewritten

PS: Before doing git filter-branch, I ran

git checkout -b my-branch

to create a new branch named my-branch (and check it out), in case git filter-branch went horribly wrong.

After seeing that git filter-branch ... left target_file unchanged, I ran git checkout -b my-branch, but I guess that did nothing. I thought it might do something, because the last line from git filter-branch seems to be saying that the branch my-branch has been changed, but I honestly do not understand what that line means.

Solution

  • It sounds like my changes exist within some deep, dark, and dank recess in git's twisted mind, and I just need a magical incantation to summon forth my changes.

    That is why you don't use git filter-branch anymore (it is obsolete, along with BFG)

    You use git filter-repo with