7-Zip Format

Purpose

This guide covers working with 7-Zip archives using Excavate.

References

Concepts

7-Zip is a high-compression archive format supporting various compression algorithms including LZMA and LZMA2. It’s commonly used for software distribution and large file compression.

Basic Usage

Extract 7-Zip Archive 

Excavate::Archive.new('archive.7z').extract

Extract Self-Extracting Archive 

# .exe files that are 7-Zip self-extracting
Excavate::Archive.new('installer.exe').extract

7-Zip Characteristics

Characteristic Description

File extension

.7z, .exe

Compression

LZMA, LZMA2, PPMD, BCJ, BCJ2

Encryption

AES-256

Max file size

16 billion GB (theoretical)

Platform

Cross-platform

Compression Methods

7-Zip supports multiple compression methods:

  • LZMA - Default, high compression ratio

  • LZMA2 - Improved LZMA with better multithreading

  • PPMD - Text compression

  • BCJ - x86 executable filter

  • BCJ2 - Enhanced x86 filter

Excavate handles all compression methods automatically.

Self-Extracting Archives

7-Zip can create self-extracting archives (.exe):

# Excavate tries 7-Zip first for .exe files
Excavate::Archive.new('sfx.exe').extract(recursive_packages: true)

If the .exe is not a 7-Zip archive, Excavate falls back to CAB extraction.

Common Use Cases

Extract Software Distribution 

Excavate::Archive.new('software.7z').extract(recursive_packages: true)

Extract Large Archives 

# 7-Zip is efficient for large files
Excavate::Archive.new('backup.7z').extract(
  filter: '**/important/**/*'
)

CLI Usage 

# Extract 7-Zip archive
excavate archive.7z

# Extract self-extracting archive
excavate installer.exe

# Recursive extraction
excavate -r package.7z

Technical Details

Excavate uses the Omnizip gem’s 7-Zip support:

  • Pure Ruby implementation

  • Supports BCJ2 filter for x86 executables

  • Handles self-extracting archives

  • No external 7-Zip binary required

Related Topics