Hi

Here's a little Python script for anyone getting the error about "no software to install" when trying to install a multi-file PKG VST on MacOS.

Spoiler: script

The script extracts each PKG file and merges the result into the correct file structure.

Presuming you've called your Python script file "extract_pkg.py":

Usage:
python3 extract_pkg.py "/path/to/folder/with/pkg/files"

Example:
python3 extract_pkg.py "/Volumes/HDD/VST Libraries/SomeLibrary"

This will create /Volumes/HDD/VST Libraries/SomeLibrary/extracted/ with all the merged payload contents.

Here's the code. Enjoy.


#!/usr/bin/env python3
"""
Simple PKG Extractor and Merger
Usage: python3 extract_pkg.py /path/to/folder/with/pkg/files
"""

import sys
import os
import subprocess
import shutil
from pathlib import Path


def extract_and_merge_pkgs(source_folder):
"""
Extract all .pkg files in source_folder and merge their payloads
into an 'extracted' subfolder.
"""
source_path = Path(source_folder).resolve()

if not source_path.exists():
print(f"Error: Folder does not exist: {source_path}")
return False

# Find all .pkg files
pkg_files = sorted(source_path.glob("*.pkg"))

if not pkg_files:
print(f"Error: No .pkg files found in {source_path}")
return False

print(f"Found {len(pkg_files)} .pkg file(s)")
print("=" * 60)

# Create temp and output directories
temp_dir = source_path / "temp_extraction"
output_dir = source_path / "extracted"

# Clean up if they exist
if temp_dir.exists():
print("Cleaning up previous temp directory...")
shutil.rmtree(temp_dir)

if output_dir.exists():
print("Cleaning up previous extracted directory...")
shutil.rmtree(output_dir)

temp_dir.mkdir()
output_dir.mkdir()

print("\nExtracting packages...")
print("=" * 60)

# Extract each package
extracted_count = 0
for i, pkg_file in enumerate(pkg_files, 1):
print(f"[{i}/{len(pkg_files)}] {pkg_file.name}")

# Create unique temp directory for this package
pkg_temp = temp_dir / f"pkg_{i}"
pkg_temp.mkdir()

# Extract using pkgutil
try:
result = subprocess.run(
["pkgutil", "--expand-full", str(pkg_file), str(pkg_temp)],
capture_output=True,
text=True
)

# Check if extraction was successful (payload exists)
payload_dir = pkg_temp / "Payload"
if payload_dir.exists():
print(f" ✓ Extracted successfully")
extracted_count += 1
else:
print(f" ✗ No Payload found (probably installer)")

except Exception as e:
print(f" ✗ Error: {e}")

print("\n" + "=" * 60)
print("Merging payloads...")
print("=" * 60)

# Merge all payload folders
merged_count = 0
for pkg_temp in sorted(temp_dir.glob("pkg_*")):
payload_dir = pkg_temp / "Payload"
if payload_dir.exists():
merged_count += 1
print(f"Merging from {pkg_temp.name}...")

# Copy contents using ditto (preserves permissions/metadata)
for item in payload_dir.iterdir():
try:
subprocess.run(
["ditto", str(item), str(output_dir / item.name)],
check=True,
capture_output=True
)
except subprocess.CalledProcessError as e:
print(f" Warning: Error copying {item.name}: {e}")

# Clean up temp directory
print("\nCleaning up temp files...")
shutil.rmtree(temp_dir)

print("\n" + "=" * 60)
print("Extraction Complete!")
print("=" * 60)
print(f"Processed: {len(pkg_files)} packages")
print(f"Extracted: {extracted_count} packages with payloads")
print(f"Merged: {merged_count} payloads")
print(f"\nOutput: {output_dir}")

# Show contents
print("\nExtracted contents:")
for item in sorted(output_dir.iterdir()):
if item.is_file():
size = item.stat().st_size
size_str = f"{size:,} bytes"
if size > 1024 * 1024:
size_str = f"{size / (1024*1024):.1f} MB"
print(f" {item.name} ({size_str})")
else:
print(f" {item.name}/ (folder)")

return True


if __name__ == "__main__":
if len(sys.argv) != 2:
print("Usage: python3 extract_pkg.py /path/to/folder/with/pkg/files")
sys.exit(1)

source_folder = sys.argv[1]
success = extract_and_merge_pkgs(source_folder)

sys.exit(0 if success else 1)

 

Last edited by a moderator: Nov 17, 2025 at 10:40 PM