Script to remove a range of commits from all branches in a given remote

removecommits.sh

#!/bin/bash
#
# Removes a range of commits in all remote branches.
#
# Disclaimer: this will remove data on your remote repository. Use at your own
# risk.

# The commit that precedes the oldest commit that needs to be removed.
PRECEDING_COMMIT=ab6ce03927e46ba4fc71a0ccb7ed5d9854242c64

# The youngest commit in the range of commits that need to be removed.
YOUNGEST_COMMIT=3edcbcf239330c41151cc0e4258263a496c49b4e

# The remote to clean.
REMOTE=origin

# Check if the oldest commit is an ancestor of the youngest commit.
if ! git merge-base --is-ancestor $PRECEDING_COMMIT $YOUNGEST_COMMIT ; then
  echo "Error: $PRECEDING_COMMIT is not an ancestor of $YOUNGEST_COMMIT."
  exit 1
fi

# Update the repository.
git fetch $REMOTE

# Loop over all the branches in the remote.
for BRANCH in `git ls-remote --heads $REMOTE | sed 's|^.*refs/heads/||'` ; do
  REMOTE_BRANCH="remotes/$REMOTE/$BRANCH"

  # Check if the branch contains the offending commits.
  if git merge-base --is-ancestor $YOUNGEST_COMMIT $REMOTE_BRANCH ; then
    echo -e "\n# Cleaning branch $BRANCH"

    # Check out the branch.
    echo "Checking out branch $REMOTE_BRANCH"
    git checkout -q $REMOTE_BRANCH

    # Clean the branch.
    echo "Removing offending commits."
    git rebase --onto $PRECEDING_COMMIT $YOUNGEST_COMMIT HEAD

    # Show a diff with the remote so that the result can be assessed.
    echo "Outputting diff with remote. Please check if the result is as expected."
    git diff $REMOTE_BRANCH

    # Ask for confirmation before overwriting the remote.
    read -p "Are you sure you want to force push the branch '$BRANCH' to the remote '$REMOTE' (y/n)? " CONFIRM
    echo $CONFIRM
    if [ "$CONFIRM" == "y" ] ; then
      echo "git push $REMOTE HEAD:$BRANCH --force"
    fi
  else
    echo -e "\n# Skipping branch ${BRANCH}. Offending commits are not present."
  fi
done