Back up your local Git directory

Therefore, first backup the directory where your local Git working directory lives.

Store the name of the official Git remote

Find out how you have named the Git remote that points to the official repository:

OFFICIAL_REMOTE=$(git remote -v \
   | grep --color=never -E \
      '[a-zA-Z0-9_-]+\s+(https://git-tails.immerda.ch/tails(?:.git)?\s+|(ssh://)?boum_org_amnesia@webmasters\.boum\.org(:wiki\.git|/~/wiki.git)).*\(fetch\)$' \
   | awk '{print $1}')
[ -n "$OFFICIAL_REMOTE" ] || echo "No official remote found."

If you see "No official remote found", then you are probably using a deprecated or unsafe URL for your official remote. You'll need to fix that first: find out what the correct URL is, and then fix it in .git/config and run the commands above again.

Delete all local tags

So that you don't publish again any deleted tag that was based on the old, non-rewritten history, delete all local tags you have:

git tag | xargs git tag -d

Fetch the rewritten history

Fetch the content of the updated official repository:

git fetch --prune "$OFFICIAL_REMOTE" && \
   git fetch "$OFFICIAL_REMOTE" --tags

Back up your existing local branches

Rename every local branch so that their name starts with the old- prefix:

for b in $(git branch --no-color) ; do
   [ "$b" != '*' ] || continue
   git branch -m "$b" "old-$b"
done

This is needed for two reasons:

• This makes sure that any work you may have started in the past, and that was not merged yet, is saved somewhere and can be salvaged later if needed.

• The old- prefix is meant to be a warning sign, so that you don't mistakenly base future work on the old, non-rewritten Git history (such work cannot be merged into the official repository anymore, as it would re-import all the data we just managed to get rid of).

Clean up your personal Git repository

If you have a personal online Git repository, please consider following these instructions.

It is not compulsory, but if you don't do that, then any new contributor who adds your personal Git repository as a Git remote will need to download hundreds of megabytes of useless data, which is not very welcoming. In particular, newcomers on your team would be negatively affected... and you want new teammates, right? :) I'm looking at you, dear translators.

So, right now your personal Git repository contains both the old (non-rewritten) and the new (rewritten) Git history. Here is how to get rid of the old one.

Set the MY_REMOTE variable

In the following command, replace XXX_REPLACE_ME with the name of the remote that points to your personal online Git repository:

MY_REMOTE=XXX_REPLACE_ME

Delete all remote branches

List branches that are in your personal online Git repository (in the following commands, ):

git branch --no-color -r --list "${MY_REMOTE}/*" \
   | grep -vE "^\s+${MY_REMOTE}/HEAD\s+"

For each such branch, check if you have work in there that can still be useful. If it's the case, then export it outside of Git, e.g. using git format-patch.

Then, delete all remote branches in your personal online Git repository:

for remote_branch in $(git branch --no-color -r --list "${MY_REMOTE}/*" \
           | grep -vE "^\s+${MY_REMOTE}/HEAD\s+") ; do
   branch=$(echo "$remote_branch" | sed -r -e "s,^${MY_REMOTE}/,,")
   git push --force "$MY_REMOTE" ":$branch"
done

Make sure you publish only up-to-date tags

Force-push the updated tags so that they replace the old ones in your personal online Git repository:

git push --force "$MY_REMOTE" --tags

Start working again

You may use git checkout as usual to create:

• a new local branch, for work you are starting right now;
• a new local branch tracking one that exists in the official repository already, for work you are following-up on.

Later, when you push a branch to your personal Git repository:

• The first time you do that, it can take a while.
• If that branch did previously exist there, then you may need to pass the --force option to git push: to avoid losing data, Git refuses to rewrite history on the remote by default, so in the rare cases when we want to do that (which is precisely the case here), one has to override this protection.