Bash script to delete all remote git branches older than provided days (runs in dry mode by default)

git_delete_stale_branches.sh

#!/bin/bash

# This script identifies and suggests deletion of remote Git branches
# that haven't been updated in a specified number of days.

usage() {
    echo "Usage: $0 <stale_days> [--force] [--path=<repo_path>]"
    echo "  <stale_days>: REQUIRED. The number of days after which a branch is considered stale."
    echo "  --force: Optional. Execute the deletion commands. By default, a dry run is performed."
    echo "  --path=<repo_path>: Optional. Specify the path to the local Git repository (defaults to current directory)."
    exit 1
}

STALE_DAYS=""
DRY_RUN=true
FORCE_DELETE=false
REPO_PATH="."

# Check if at least one argument (stale_days) is provided
if [ -z "$1" ]; then
    usage
fi

# The first argument is always STALE_DAYS
STALE_DAYS="$1"

# Validate STALE_DAYS is a positive integer
if ! [[ "$STALE_DAYS" =~ ^[0-9]+$ ]] || [ "$STALE_DAYS" -le 0 ]; then
    echo "Error: <stale_days> must be a positive integer."
    usage
fi

# Shift the first argument (STALE_DAYS) out, then parse remaining optional arguments
shift

for arg in "$@"; do
    case "$arg" in
        --force)
            FORCE_DELETE=true
            DRY_RUN=false
            ;;
        --path=*)
            REPO_PATH="${arg#*=}"
            ;;
        *)
            echo "Error: Unknown argument '$arg'"
            usage
            ;;
    esac
done

echo "Analyzing repository: $REPO_PATH"
if [ "$DRY_RUN" = true ]; then
    echo "Running in DRY RUN mode. No branches will be deleted."
else
    echo "Running in FORCE mode. Branches will be deleted."
fi
echo "---------------------------------------------------------------------"

echo "Fetching the latest remote branch information and syncing with local branches..."
# Fetch all remote branches to ensure we have the most up-to-date information
# Use -C to specify the repository path
git -C "$REPO_PATH" fetch --prune

echo ""
echo "Calculating age for all remote branches (excluding main/master/1.x)..."
echo "---------------------------------------------------------------------"

branches_to_delete=()

OLDEST_STALE_BRANCH_NAME=""
NEWEST_STALE_BRANCH_NAME=""
OLDEST_STALE_TIMESTAMP=0 # Initialize with a very old timestamp
NEWEST_STALE_TIMESTAMP=$(date +%s) # Initialize with current timestamp

# Array to store all branch info for sorting: "age_days|commit_date|branch_name"
declare -a ALL_BRANCH_AGES=()

current_timestamp=$(date +%s)

# Create a temporary file to store branch data to avoid subshell issues
TEMP_BRANCH_FILE=$(mktemp)
if [ -z "$TEMP_BRANCH_FILE" ]; then
    echo "Error: Could not create temporary file."
    exit 1
fi

# Populate the temporary file with branch data
git -C "$REPO_PATH" for-each-ref --format='%(committerdate:unix) %(committerdate:format:%Y-%m-%d) %(refname:short)' refs/remotes/origin/ > "$TEMP_BRANCH_FILE"

# Loop through the temporary file to process branch data
while read commit_timestamp_raw commit_date branch; do
    # Convert commit_timestamp_raw to integer
    commit_timestamp=$((commit_timestamp_raw))

    # Calculate difference in seconds, then convert to days
    age_seconds=$((current_timestamp - commit_timestamp))
    age_days=$((age_seconds / (60 * 60 * 24)))

    # Exclude HEAD and master/main/1.x branches from being considered stale or listed here
    if [[ "$branch" != "origin/HEAD" && "$branch" != "origin/master" && "$branch" != "origin/main" && "$branch" != "origin/1.x" ]]; then
        # Store info for sorting: "age_days|commit_date|branch_name"
        ALL_BRANCH_AGES+=("$age_days|$commit_date|${branch#origin/}")

        if (( age_days > STALE_DAYS )); then
            # Add the branch name (without 'origin/') to the array
            branches_to_delete+=("${branch#origin/}")

            if [ -z "$OLDEST_STALE_BRANCH_NAME" ] || (( commit_timestamp < OLDEST_STALE_TIMESTAMP )); then
                OLDEST_STALE_TIMESTAMP=$commit_timestamp
                OLDEST_STALE_BRANCH_NAME="${branch#origin/}"
            fi
            if [ -z "$NEWEST_STALE_BRANCH_NAME" ] || (( commit_timestamp > NEWEST_STALE_TIMESTAMP )); then
                NEWEST_STALE_TIMESTAMP=$commit_timestamp
                NEWEST_STALE_BRANCH_NAME="${branch#origin/}"
            fi
        fi
    fi
done < "$TEMP_BRANCH_FILE"

# Clean up the temporary file
rm "$TEMP_BRANCH_FILE"

# Sort the ALL_BRANCH_AGES array by age (numeric sort on the first field)
# Using printf "%s\n" "${ALL_BRANCH_AGES[@]}" to handle potential newlines in branch names,
# then piping to sort.
IFS=$'\n' sorted_branches=($(printf "%s\n" "${ALL_BRANCH_AGES[@]}" | sort -n -t'|' -k1))
unset IFS

# Print the sorted list of all branches
for branch_info in "${sorted_branches[@]}"; do
    # Split the string back into components using IFS
    IFS='|' read -r age_days commit_date branch_name <<< "$branch_info"
    echo "  Branch: $branch_name (Last commit: $commit_date, Age: $age_days days)"
done

echo "---------------------------------------------------------------------"

if [ ${#branches_to_delete[@]} -eq 0 ]; then
    echo "No stale remote branches found older than $STALE_DAYS days in $REPO_PATH."
else
    echo ""
    echo "Summary of stale branches in $REPO_PATH (older than $STALE_DAYS days):"
    echo "  Number of branches to delete: ${#branches_to_delete[@]}"
    if [ -n "$NEWEST_STALE_BRANCH_NAME" ]; then
        # Use date -r for BSD date compatibility
        echo "  Newest stale branch: $NEWEST_STALE_BRANCH_NAME (Last updated: $(date -r "$NEWEST_STALE_TIMESTAMP" +%Y-%m-%d))"
    fi
    if [ -n "$OLDEST_STALE_BRANCH_NAME" ]; then
        # Use date -r for BSD date compatibility
        echo "  Oldest stale branch: $OLDEST_STALE_BRANCH_NAME (Last updated: $(date -r "$OLDEST_STALE_TIMESTAMP" +%Y-%m-%d))"
    fi
    echo ""

    if [ "$FORCE_DELETE" = true ]; then
        echo "Deleting the identified stale branches..."
        # Execute the deletion commands
        for branch in "${branches_to_delete[@]}"; do
            echo "Executing: git push origin --delete $branch"
            git -C "$REPO_PATH" push origin --delete "$branch"
        done
        echo ""
        echo "Deletion process complete."
    else
        echo "To delete these branches, run the script with the --force option:"
        echo ""
        echo "Example: $0 $STALE_DAYS --force --path=\"$REPO_PATH\""
        echo ""
        echo "Please review the summary carefully before executing the commands."
    fi
fi