update-ref Git Command Guide

The git update-ref command safely updates the object name stored in a reference (ref), providing atomic operations for branch and tag management. It’s a low-level command that offers precise control over Git references with safety guarantees and transactional behavior.

git update-ref Syntax:

git update-ref [-d] [-z] [--stdin] [--no-deref] [--create-reflog]
                [-m <reason>] [--no-refs] <ref> <newvalue> [<oldvalue>]
git update-ref [--no-deref] [-m <reason>] --stdin [--no-refs]

Reference Update Options:

Option	Description
-d, --delete	Delete reference
-z	Use NUL character as delimiter
--stdin	Read updates from stdin
--no-deref	Don’t dereference symbolic refs
--create-reflog	Create reflog entry
-m <reason>	Reason for update (reflog)

Safety Options:

Option	Description
<oldvalue>	Expected current value (CAS)
--no-refs	Don’t verify refs namespace

Parameters:

Parameter	Description
<ref>	Reference to update
<newvalue>	New object SHA-1 or ref
<oldvalue>	Expected current value

Understanding Reference Operations:

Git Reference Types:

Reference Hierarchy:
├── Direct References: Point to objects
│   ├── refs/heads/main -> commit SHA-1
│   ├── refs/tags/v1.0 -> commit SHA-1
│   └── refs/remotes/origin/main -> commit SHA-1
│
└── Symbolic References: Point to other refs
    ├── HEAD -> refs/heads/main
    ├── ORIG_HEAD -> commit SHA-1
    └── MERGE_HEAD -> commit SHA-1

Atomic Operations:

Atomic Reference Updates:
├── Compare-and-Swap (CAS): Verify old value before update
├── Transactional: All-or-nothing updates
├── Lock-Free: Uses filesystem locking
├── Safe Concurrency: Multiple processes can update safely
└── Reflog Integration: Automatic history tracking

Reference Resolution:

Reference Resolution Chain:
Reference Name
├── refs/heads/feature -> Direct ref
├── refs/tags/v1.0 -> Direct ref
├── HEAD -> Symbolic ref -> refs/heads/main
└── refs/remotes/origin/HEAD -> Symbolic ref -> refs/remotes/origin/main

Basic Update-Ref Operations:

Updating Branch References:

# Update branch to new commit
git update-ref refs/heads/main abc123def456

# Update with safety check
git update-ref refs/heads/main abc123def456 789def012345

# Update symbolic ref
git update-ref HEAD refs/heads/develop

Creating and Deleting References:

# Create new branch reference
git update-ref refs/heads/feature-branch abc123def456

# Create tag reference
git update-ref refs/tags/v1.0 abc123def456

# Delete reference
git update-ref -d refs/heads/old-branch

# Delete tag
git update-ref -d refs/tags/old-tag

Safe Reference Updates:

# Update only if current value matches
git update-ref refs/heads/main new-commit-sha current-commit-sha

# Update with reflog message
git update-ref -m "Merge pull request #123" refs/heads/main merge-commit-sha

# Create reflog entry
git update-ref --create-reflog refs/heads/feature new-commit-sha

Advanced Update-Ref Scenarios:

Batch Reference Operations:

# Update multiple refs from stdin
git update-ref --stdin << EOF
update refs/heads/main abc123def456 789def012345
update refs/heads/develop def456ghi789 abc123def456
delete refs/heads/old-feature
EOF

# Process refs with NUL delimiter
printf 'update refs/heads/main\x00abc123\x00789def\x00' | git update-ref -z --stdin

Symbolic Reference Management:

# Update HEAD to point to different branch
git update-ref HEAD refs/heads/release

# Update remote HEAD
git update-ref refs/remotes/origin/HEAD refs/remotes/origin/main

# Create symbolic reference
git update-ref refs/heads/current refs/heads/main

Reference Maintenance:

# Clean up dangling references
git for-each-ref --format='%(refname)' | while read -r ref; do
    if ! git show-ref --verify "$ref" >/dev/null 2>&1; then
        echo "Removing dangling ref: $ref"
        git update-ref -d "$ref"
    fi
done

# Update remote tracking branches
git update-ref refs/remotes/origin/main "$(git rev-parse origin/main)"

Transactional Operations:

# Atomic multi-ref update
update_multiple_refs() {
    local main_commit="$1"
    local develop_commit="$2"

    # Use stdin for atomic updates
    git update-ref --stdin << EOF
update refs/heads/main $main_commit $(git rev-parse refs/heads/main)
update refs/heads/develop $develop_commit $(git rev-parse refs/heads/develop)
EOF

    if [ $? -eq 0 ]; then
        echo "Successfully updated both branches"
    else
        echo "Failed to update branches atomically"
    fi
}

# Usage
update_multiple_refs "abc123" "def456"

Configuration and Best Practices:

Git Configuration for Update-Ref:

# Configure reflog behavior
git config core.logAllRefUpdates true      # Enable reflog for all refs
git config core.logAllRefUpdates always    # Always create reflog

# Configure reference verification
git config receive.denyDeletes false       # Allow ref deletion
git config receive.denyDeleteCurrent false # Allow deleting current branch

# Configure reflog expiration
git config gc.reflogExpire 90.days         # Keep reflogs for 90 days
git config gc.reflogExpireUnreachable 30.days

Safe Update-Ref Operations:

# Always verify before update
safe_update_ref() {
    local ref="$1"
    local new_value="$2"
    local expected_old="${3:-}"

    # Get current value
    local current_value
    current_value=$(git rev-parse "$ref" 2>/dev/null || echo "")

    # Check if update is needed
    if [ "$current_value" = "$new_value" ]; then
        echo "Ref $ref already at $new_value"
        return 0
    fi

    # Perform safe update
    if [ -n "$expected_old" ]; then
        git update-ref "$ref" "$new_value" "$expected_old"
    else
        git update-ref "$ref" "$new_value"
    fi
}

# Backup refs before major operations
backup_refs() {
    echo "Backing up references..."

    git for-each-ref --format='%(refname) %(objectname)' > refs-backup.txt

    echo "Backup saved to refs-backup.txt"
}

# Restore refs from backup
restore_refs() {
    local backup_file="${1:-refs-backup.txt}"

    echo "Restoring references from $backup_file..."

    while read -r ref sha; do
        git update-ref "$ref" "$sha" 2>/dev/null || echo "Failed to restore $ref"
    done < "$backup_file"

    echo "Reference restoration complete"
}

Performance Optimization:

# Batch reference updates
batch_update_refs() {
    echo "Performing batch reference updates..."

    # Collect updates
    updates_file=$(mktemp)
    echo "update refs/heads/main abc123 $(git rev-parse refs/heads/main)" >> "$updates_file"
    echo "update refs/heads/develop def456 $(git rev-parse refs/heads/develop)" >> "$updates_file"

    # Execute atomically
    git update-ref --stdin < "$updates_file"

    # Cleanup
    rm "$updates_file"
}

# Optimize reflog operations
optimize_reflog() {
    echo "Optimizing reflog operations..."

    # Disable reflog for performance
    git config core.logAllRefUpdates false

    # Perform updates
    # ... update operations ...

    # Re-enable reflog
    git config core.logAllRefUpdates true
}

Integration with Development Workflows:

Branch Management Automation:

#!/bin/bash
# Automated branch management with update-ref

create_feature_branch() {
    local feature_name="$1"
    local base_branch="${2:-main}"

    echo "Creating feature branch: $feature_name"

    # Get base commit
    base_commit=$(git rev-parse "$base_branch")

    # Create branch reference
    git update-ref "refs/heads/feature/$feature_name" "$base_commit"

    # Set upstream
    git config "branch.feature/$feature_name.remote" origin
    git config "branch.feature/$feature_name.merge" "refs/heads/feature/$feature_name"

    echo "Feature branch created and configured"
}

# Automated branch cleanup
cleanup_merged_branches() {
    echo "Cleaning up merged branches..."

    git for-each-ref --format='%(refname:short) %(objectname)' refs/heads/feature/ | while read -r branch sha; do
        if git merge-base --is-ancestor "$sha" main; then
            echo "Deleting merged branch: $branch"
            git update-ref -d "refs/heads/$branch"
        fi
    done

    echo "Branch cleanup complete"
}

# Usage
create_feature_branch "user-authentication"
cleanup_merged_branches

Release Management:

# Release tagging with update-ref
create_release_tag() {
    local version="$1"
    local release_commit="$2"

    echo "Creating release tag: v$version"

    # Create annotated tag object
    tag_object=$(git mktag << EOF
object $release_commit
type commit
tag v$version
tagger $(git config user.name) <$(git config user.email)> $(date +%s) +0000

Release v$version

Release notes:
- Feature 1
- Feature 2
- Bug fixes
EOF
)

    # Update tag reference
    git update-ref "refs/tags/v$version" "$tag_object"

    echo "Release tag v$version created"
}

# Automated version bumping
bump_version() {
    local new_version="$1"

    echo "Bumping version to $new_version"

    # Update version file
    echo "$new_version" > VERSION

    # Commit version change
    version_commit=$(git commit-tree -p HEAD -m "Bump version to $new_version" VERSION)

    # Update main branch
    git update-ref refs/heads/main "$version_commit"

    # Create version tag
    git update-ref "refs/tags/v$new_version" "$version_commit"

    echo "Version bumped to $new_version"
}

# Usage
create_release_tag "2.1.0" "abc123def456"
bump_version "2.1.0"

Repository Synchronization:

# Repository synchronization with update-ref
sync_repository_refs() {
    local remote_name="$1"

    echo "Synchronizing references with $remote_name..."

    # Fetch remote refs
    git fetch "$remote_name"

    # Update remote tracking branches
    git for-each-ref --format='%(refname:short)' "refs/remotes/$remote_name/" | while read -r remote_ref; do
        local_ref="refs/heads/${remote_ref#refs/remotes/$remote_name/}"

        # Skip HEAD
        if [[ "$remote_ref" == */HEAD ]]; then
            continue
        fi

        remote_commit=$(git rev-parse "$remote_ref")
        git update-ref "$local_ref" "$remote_commit" 2>/dev/null && \
            echo "Updated $local_ref to $remote_commit" || \
            echo "Skipped $local_ref (possibly protected)"
    done

    echo "Repository synchronization complete"
}

# Usage
sync_repository_refs "origin"

Troubleshooting Common Issues:

Reference Update Conflicts:

# Handle concurrent update conflicts
handle_update_conflict() {
    local ref="$1"
    local new_value="$2"
    local max_attempts=5
    local attempt=1

    while [ $attempt -le $max_attempts ]; do
        current_value=$(git rev-parse "$ref" 2>/dev/null || echo "")

        if git update-ref "$ref" "$new_value" "$current_value"; then
            echo "Successfully updated $ref on attempt $attempt"
            return 0
        fi

        echo "Update conflict on attempt $attempt, retrying..."
        sleep 1
        ((attempt++))
    done

    echo "Failed to update $ref after $max_attempts attempts"
    return 1
}

# Usage
handle_update_conflict "refs/heads/main" "new-commit-sha"

Reference Corruption:

# Detect and fix corrupted references
fix_corrupted_refs() {
    echo "Checking for corrupted references..."

    git for-each-ref | while read -r sha type ref; do
        if ! git cat-file -e "$sha" 2>/dev/null; then
            echo "Corrupted reference: $ref -> $sha"

            # Try to find correct commit
            correct_sha=$(git log --oneline -1 --grep="$ref" --format=%H 2>/dev/null || echo "")

            if [ -n "$correct_sha" ]; then
                echo "Fixing $ref to point to $correct_sha"
                git update-ref "$ref" "$correct_sha"
            else
                echo "Cannot fix $ref, removing..."
                git update-ref -d "$ref"
            fi
        fi
    done

    echo "Reference corruption check complete"
}

Permission Issues:

# Handle permission issues with references
fix_ref_permissions() {
    echo "Fixing reference permissions..."

    # Fix .git/refs permissions
    find .git/refs -type f -exec chmod 644 {} \;
    find .git/refs -type d -exec chmod 755 {} \;

    # Fix packed-refs permissions
    [ -f .git/packed-refs ] && chmod 644 .git/packed-refs

    # Fix reflog permissions
    find .git/logs -type f -exec chmod 644 {} \; 2>/dev/null || true

    echo "Reference permissions fixed"
}

# Test reference access
test_ref_access() {
    local ref="$1"

    if git update-ref "$ref" "$(git rev-parse HEAD)" 2>/dev/null; then
        echo "Reference $ref is writable"
    else
        echo "Reference $ref is not writable"
        return 1
    fi
}

Reflog Issues:

# Fix reflog problems
repair_reflog() {
    local ref="$1"

    echo "Repairing reflog for $ref..."

    reflog_file=".git/logs/${ref#refs/}"

    # Backup current reflog
    cp "$reflog_file" "${reflog_file}.backup" 2>/dev/null || true

    # Rebuild reflog from history
    git log --oneline --format="%H %ct %s" "$ref" | while read -r commit timestamp message; do
        echo "$commit $timestamp reflog-entry" >> "${reflog_file}.new"
    done

    # Replace reflog
    mv "${reflog_file}.new" "$reflog_file" 2>/dev/null || echo "Could not update reflog"

    echo "Reflog repair attempt complete"
}

# Clean old reflog entries
clean_reflog() {
    echo "Cleaning old reflog entries..."

    # Expire old entries
    git reflog expire --all --expire=30.days

    # Pack reflogs
    git reflog pack

    echo "Reflog cleanup complete"
}

Symbolic Reference Issues:

# Fix broken symbolic references
fix_symbolic_refs() {
    echo "Checking symbolic references..."

    # Check HEAD
    if ! git rev-parse HEAD >/dev/null 2>&1; then
        echo "HEAD is broken, fixing..."
        git update-ref HEAD refs/heads/main
    fi

    # Check other symbolic refs
    for sym_ref in ORIG_HEAD MERGE_HEAD CHERRY_PICK_HEAD; do
        if git show-ref "$sym_ref" >/dev/null 2>&1; then
            target=$(git rev-parse "$sym_ref" 2>/dev/null)
            if [ -z "$target" ]; then
                echo "Removing broken $sym_ref"
                git update-ref -d "$sym_ref"
            fi
        fi
    done

    echo "Symbolic reference check complete"
}

Caution

git update-ref modifies references directly. Use carefully as incorrect updates can break repository history. Always backup before operations.

Real-World Usage Examples:

Advanced Branch Management:

#!/bin/bash
# Advanced branch management with update-ref

# Atomic branch operations
atomic_branch_operations() {
    echo "=== Atomic Branch Operations ==="

    # Create multiple branches atomically
    create_branches() {
        local base_commit="$1"
        shift
        local branches=("$@")

        echo "Creating branches atomically..."

        # Prepare updates
        updates=""
        for branch in "${branches[@]}"; do
            updates+="update refs/heads/$branch $base_commit\n"
        done

        # Execute atomically
        echo -e "$updates" | git update-ref --stdin

        if [ $? -eq 0 ]; then
            echo "Successfully created ${#branches[@]} branches"
        else
            echo "Failed to create branches atomically"
        fi
    }

    # Rename branch safely
    rename_branch() {
        local old_name="$1"
        local new_name="$2"

        echo "Renaming branch $old_name to $new_name..."

        # Get current commit
        current_commit=$(git rev-parse "refs/heads/$old_name")

        # Create new branch
        git update-ref "refs/heads/$new_name" "$current_commit"

        # Update HEAD if pointing to old branch
        if [ "$(git rev-parse HEAD)" = "$current_commit" ]; then
            git update-ref HEAD "refs/heads/$new_name"
        fi

        # Delete old branch
        git update-ref -d "refs/heads/$old_name"

        echo "Branch renamed successfully"
    }

    # Interactive operations
    echo "Branch Operations:"
    echo "1. Create multiple branches"
    echo "2. Rename branch safely"

    read -p "Select operation (1-2): " op

    case "$op" in
        1)
            read -p "Base commit: " base
            read -p "Branches (space-separated): " -a branches
            create_branches "$base" "${branches[@]}"
            ;;
        2)
            read -p "Old branch name: " old
            read -p "New branch name: " new
            rename_branch "$old" "$new"
            ;;
    esac
}

atomic_branch_operations

Tag Management System:

# Advanced tag management with update-ref
tag_management_system() {
    echo "=== Tag Management System ==="

    # Create annotated tag manually
    create_annotated_tag() {
        local tag_name="$1"
        local commit="$2"
        local message="$3"

        echo "Creating annotated tag: $tag_name"

        # Create tag object
        tag_object=$(git mktag << EOF
object $commit
type commit
tag $tag_name
tagger $(git config user.name) <$(git config user.email)> $(date +%s) +0000

$message
EOF
)

        # Update tag reference
        git update-ref "refs/tags/$tag_name" "$tag_object"

        echo "Annotated tag $tag_name created"
    }

    # Batch tag operations
    batch_tag_operations() {
        echo "Performing batch tag operations..."

        # Prepare tag updates
        updates=""

        # Example: Tag all release commits
        git log --oneline --grep="Release" --format="%H %s" | while read -r commit subject; do
            version=$(echo "$subject" | sed 's/Release v//')
            if [[ "$version" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
                updates+="update refs/tags/v$version $commit\n"
            fi
        done

        # Execute batch update
        echo -e "$updates" | git update-ref --stdin

        echo "Batch tag operations complete"
    }

    # Tag cleanup
    cleanup_tags() {
        local pattern="$1"

        echo "Cleaning up tags matching: $pattern"

        git for-each-ref --format='%(refname)' "refs/tags/$pattern" | while read -r tag_ref; do
            echo "Removing tag: ${tag_ref#refs/tags/}"
            git update-ref -d "$tag_ref"
        done

        echo "Tag cleanup complete"
    }

    # Interactive tag management
    echo "Tag Management Options:"
    echo "1. Create annotated tag"
    echo "2. Batch tag operations"
    echo "3. Cleanup tags"

    read -p "Select option (1-3): " option

    case "$option" in
        1)
            read -p "Tag name: " tag_name
            read -p "Commit: " commit
            read -p "Message: " message
            create_annotated_tag "$tag_name" "$commit" "$message"
            ;;
        2) batch_tag_operations ;;
        3)
            read -p "Pattern to match: " pattern
            cleanup_tags "$pattern"
            ;;
    esac
}

tag_management_system

Repository Maintenance Automation:

# Repository maintenance with update-ref
automated_maintenance() {
    echo "=== Automated Repository Maintenance ==="

    # Clean up stale branches
    cleanup_stale_branches() {
        local max_age_days="${1:-90}"

        echo "Cleaning up branches older than $max_age_days days..."

        git for-each-ref --format='%(refname) %(creatordate:format:%s)' refs/heads/ | while read -r ref create_time; do
            current_time=$(date +%s)
            age_days=$(( (current_time - create_time) / 86400 ))

            if [ "$age_days" -gt "$max_age_days" ]; then
                # Check if merged
                branch_commit=$(git rev-parse "$ref")
                if git merge-base --is-ancestor "$branch_commit" main 2>/dev/null; then
                    echo "Removing merged branch: ${ref#refs/heads/} (age: ${age_days} days)"
                    git update-ref -d "$ref"
                fi
            fi
        done

        echo "Stale branch cleanup complete"
    }

    # Update remote references
    update_remote_refs() {
        local remote="${1:-origin}"

        echo "Updating remote references for $remote..."

        # Fetch latest
        git fetch "$remote"

        # Update remote refs
        git ls-remote "$remote" | while read -r sha ref; do
            if [[ "$ref" == refs/heads/* ]]; then
                local_ref="refs/remotes/$remote/${ref#refs/heads/}"
                git update-ref "$local_ref" "$sha"
            fi
        done

        echo "Remote references updated"
    }

    # Reflog maintenance
    maintain_reflog() {
        echo "Maintaining reflog..."

        # Expire old entries
        git reflog expire --all --expire=30.days

        # Pack reflogs
        git reflog pack

        # Clean unreachable reflog entries
        git reflog expire --all --expire-unreachable=now

        echo "Reflog maintenance complete"
    }

    # Interactive maintenance
    echo "Maintenance Options:"
    echo "1. Clean up stale branches"
    echo "2. Update remote references"
    echo "3. Maintain reflog"

    read -p "Select option (1-3): " option

    case "$option" in
        1)
            read -p "Max age in days (default: 90): " max_age
            cleanup_stale_branches "${max_age:-90}"
            ;;
        2)
            read -p "Remote name (default: origin): " remote
            update_remote_refs "${remote:-origin}"
            ;;
        3) maintain_reflog ;;
    esac
}

automated_maintenance

Custom Git Commands:

# Custom Git commands using update-ref
custom_git_commands() {
    echo "=== Custom Git Commands ==="

    # Safe force push
    safe_force_push() {
        local branch="$1"
        local remote="${2:-origin}"

        echo "Performing safe force push of $branch to $remote..."

        # Get remote commit
        remote_commit=$(git rev-parse "refs/remotes/$remote/$branch" 2>/dev/null || echo "")

        # Get local commit
        local_commit=$(git rev-parse "refs/heads/$branch")

        # Check if force is necessary
        if [ "$remote_commit" = "$local_commit" ]; then
            echo "Branch is already up to date"
            return 0
        fi

        # Check if local is descendant of remote
        if git merge-base --is-ancestor "$remote_commit" "$local_commit" 2>/dev/null; then
            echo "Safe to push (local is descendant)"
            git update-ref "refs/remotes/$remote/$branch" "$local_commit"
        else
            echo "Force push required - checking safety..."

            # Additional safety checks
            if [ -n "$remote_commit" ]; then
                # Check how many commits would be lost
                lost_commits=$(git rev-list "$remote_commit..HEAD" | wc -l)
                if [ "$lost_commits" -gt 10 ]; then
                    echo "Warning: Would lose $lost_commits commits"
                    read -p "Continue? (yes/no): " confirm
                    if [ "$confirm" != "yes" ]; then
                        return 1
                    fi
                fi
            fi

            # Perform force update
            git update-ref "refs/remotes/$remote/$branch" "$local_commit"
            echo "Force push completed safely"
        fi
    }

    # Branch snapshot
    create_branch_snapshot() {
        local branch="$1"
        local snapshot_name="${2:-snapshot-$(date +%Y%m%d-%H%M%S)}"

        echo "Creating snapshot of branch $branch as $snapshot_name..."

        current_commit=$(git rev-parse "refs/heads/$branch")
        git update-ref "refs/snapshots/$snapshot_name" "$current_commit"

        echo "Snapshot created: refs/snapshots/$snapshot_name -> $current_commit"
    }

    # Restore from snapshot
    restore_from_snapshot() {
        local snapshot_name="$1"
        local target_branch="$2"

        echo "Restoring $target_branch from snapshot $snapshot_name..."

        snapshot_commit=$(git rev-parse "refs/snapshots/$snapshot_name")
        git update-ref "refs/heads/$target_branch" "$snapshot_commit"

        echo "Branch $target_branch restored from snapshot"
    }

    # Interactive custom commands
    echo "Custom Git Commands:"
    echo "1. Safe force push"
    echo "2. Create branch snapshot"
    echo "3. Restore from snapshot"

    read -p "Select command (1-3): " cmd

    case "$cmd" in
        1)
            read -p "Branch: " branch
            read -p "Remote (default: origin): " remote
            safe_force_push "$branch" "${remote:-origin}"
            ;;
        2)
            read -p "Branch: " branch
            read -p "Snapshot name (optional): " snapshot
            create_branch_snapshot "$branch" "$snapshot"
            ;;
        3)
            read -p "Snapshot name: " snapshot
            read -p "Target branch: " branch
            restore_from_snapshot "$snapshot" "$branch"
            ;;
    esac
}

custom_git_commands

Tip

Use git update-ref for atomic reference operations and low-level ref management. Always specify old value for safe updates. Use —stdin for batch operations. ::>

What’s the difference between git update-ref and direct file editing?

git update-ref provides atomic, safe operations with locking; direct editing can cause corruption and race conditions.

How do I safely update a branch reference?

git update-ref refs/heads/branch new-commit-sha old-commit-sha uses compare-and-swap for safety.

Can update-ref work with symbolic references?

Yes, git update-ref HEAD refs/heads/main updates HEAD to point to main branch.

How do I delete a reference with update-ref?

git update-ref -d refs/heads/branch-name deletes the reference safely.

What’s the —stdin option for?

—stdin reads multiple reference updates from standard input for atomic batch operations.

Can update-ref create reflog entries?

Yes, —create-reflog forces reflog creation, -m adds custom reflog messages.

How do I handle concurrent reference updates?

Use the old value parameter for compare-and-swap operations to detect conflicts.

Can update-ref work with remote references?

Yes, but typically used for local refs. Remote refs are usually updated through fetch/push.

What’s the difference between update-ref and symbolic-ref?

update-ref works with any reference type; symbolic-ref specifically handles symbolic references like HEAD.

How do I backup references before operations?

git for-each-ref —format=’%(refname) %(objectname)’ > refs-backup.txt saves all refs.

Can update-ref work with tag references?

Yes, git update-ref refs/tags/v1.0 commit-sha creates or updates tags.

How do I check if a reference update succeeded?

Check the exit code: git update-ref returns 0 on success, non-zero on failure.

Can update-ref work with packed references?

Yes, update-ref handles both loose and packed references transparently.

What’s the —no-deref option for?

—no-deref prevents dereferencing symbolic refs, operating on the symbolic ref itself.

How do I update multiple references atomically?

Use —stdin with multiple update commands for transactional multi-ref updates.

Can update-ref work with Git worktrees?

Yes, each worktree has its own references that can be updated independently.

How do I recover from a failed update-ref operation?

Check reflog, use backup refs, or restore from known good state.

Applications of the git update-ref command

1. Atomic Reference Operations: Safe, transactional updates to Git references
2. Branch Management: Create, update, and delete branch references programmatically
3. Tag Management: Create and manage tag references with custom metadata
4. Repository Maintenance: Clean up and maintain reference integrity
5. Automation Scripts: Implement custom Git workflows with precise ref control
6. Batch Operations: Perform multiple reference updates atomically
7. Backup and Recovery: Create and restore reference snapshots
8. Integration Tools: Support external tools requiring low-level ref manipulation