Synchronize local branches with remotes (remove gone branches and fast-forward the others)

git-sync.sh

#!/usr/bin/env bash
# Synchronize local branches with remotes.
#
# It removes gone branches and fast-forward the others.

echo 'Fetching remotes...'
git fetch --prune
echo

BRANCHES=$(git for-each-ref refs/heads/ --format='%(upstream:short):%(refname:short)~%(upstream:track)')
CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)

BRANCHES_TO_FF=$(grep -v -e '~\[gone\]$' -e ":$CURRENT_BRANCH" <<< "$BRANCHES" | grep '^[^:].*~.')
if [[ -n $BRANCHES_TO_FF ]]; then
    echo 'Fast-forwarding local branches...'
    while read -r BRANCH; do
        echo "Update $(tr '~' ' ' <<< "${BRANCH#*:}")"
        git fetch . "${BRANCH%~*}"
        echo
    done <<< "$BRANCHES_TO_FF"
fi

if grep -q ".*:$CURRENT_BRANCH~." <<< "$BRANCHES"; then
    echo 'Pulling current branch...'
    git pull
    echo
fi

GONE_BRANCHES=$(grep '~\[gone\]$' <<< "$BRANCHES" | sed -e 's/^.*://; s/~.*$//')
if [[ -n $GONE_BRANCHES ]]; then
    echo 'Removing gone branches...'
    # shellcheck disable=SC2086
    git branch -d $GONE_BRANCHES
fi