undo “git filter-branch … — --all”? in one command?

Question

I started messing around with git filter-branch. The --all option rewrites all branches and tags. Cool. git filter-branch creates a backup of all re

Answer 1

Here's a simple and safe way to undo a filter-branch:

git fetch . +refs/original/*:*

If the currently checked out branch (HEAD) is one of the branches to be restored, this command will fail. You can run git checkout --detach beforehand to let git fetch update all branches. Remember to checkout a branch after running git fetch!

Once the refs have been successfully restored, you can delete the refs/original refs safely with this command:

git for-each-ref refs/original --format='delete %(refname) %(objectname)' | git update-ref --stdin

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Old answer:

git for-each-ref refs/heads refs/tags \
        --format='git update-ref "%(refname)" "%(refname)@{1 hour ago}"'

For added safety you could test whether the filter-branch actually did update the ref:

git for-each-ref refs/heads refs/tags --format='
        { git reflog -1 "%(refname)" | sed -n "/filter-branch: rewrite$/Q1"; } \
                  || git update-ref -m "reset to before filter-branch" \
                             %(refname) %(refname)@{1}' | sh -x