Prune git branches and update default branch

git-clean.sh

#!/bin/bash
set -euo pipefail

# Verify we're in a git repo
git rev-parse --git-dir > /dev/null 2>&1 || { echo "Not a git repository"; exit 1; }

# Abort if there are uncommitted changes
if ! git diff-index --quiet HEAD -- 2>/dev/null; then
  echo "You have uncommitted changes. Stash or commit them first."
  exit 1
fi

# Detect default branch (local, no network call)
BRANCH=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's|refs/remotes/origin/||')
if [ -z "$BRANCH" ]; then
  # Fallback: query remote
  BRANCH=$(git remote show origin | sed -n '/HEAD branch/s/.*: //p')
fi

# Single fetch that also prunes deleted remote branches
echo "Fetching and pruning..."
git fetch --prune origin

# Switch to default branch and fast-forward
echo "Switching to $BRANCH..."
git checkout "$BRANCH"
git merge --ff-only "origin/$BRANCH"

# Delete local branches whose remote is gone
echo "Deleting merged local branches..."
git branch --format='%(refname:short) %(upstream:track)' \
  | awk '$2 == "[gone]" { print $1 }' \
  | xargs -r git branch -D 2>/dev/null || true

# Garbage collect
echo "Running gc..."
git gc --quiet

echo "Done. Remaining branches:"
git branch --list

Suggestion:

I've added a little change to save the branches list in a file and open it to edition, this way I can exclude branches I don't want to remove now before closing the file.

#!/bin/bash
echo "Changing branch to master"
git checkout master
echo "Update changes"
git fetch
git pull
echo "Prunning local branches that were removed in remote..."
git remote update --prune
# saves in a file to pre-deletion check
git fetch -p && for branch in `git branch -vv | grep ': gone]' | awk '{print $1}'`; do echo $branch >>/tmp/merged-branches; done 
# (here you can remove branches you don't want to delete)
vi /tmp/merged-branches && xargs git branch -D </tmp/merged-branches
echo "Done"
echo "Listing remaining branches:"
git branch --list