A Ruby gem to compare log files with intelligent normalization of timestamps, GUIDs, and other variable data.

Install the gem:

gem install compare_logs

Or add it to your Gemfile:

gem 'compare_logs'

Then run:

bundle install

Compare the two most recent log files in your Downloads folder:

compare_logs

Compare action logs for a specific platform:

compare_logs actions ubuntu-2004

Compare specific files:

compare_logs file1.log file2.log

Show help:

compare_logs help

require 'compare_logs'

comparator = CompareLogs::Comparator.new(['file1.log', 'file2.log'])
comparator.run

CompareLogs normalizes variable data in log files to make meaningful comparisons easier:

• Timestamps (various formats)
• GUIDs and GUID-like identifiers
• Build paths
• Timing measurements
• Directory names with timestamps

After normalization, it opens the files in gvimdiff for visual comparison.

• --aggressive - Remove all lines that are identical in both files after normalization
• --ignore-versions - Normalize x.y.z version strings to VERSION
• --ignore-timings - Normalize timing strings (e.g., '1.234 seconds') to TIMING

Options can be combined for maximum noise reduction.

You can add your own custom substitutions using a config file at ~/.compare_logs:

# Format: pattern|||replacement (use ||| as separator)
# One pattern per line, lines starting with # are comments

/my/custom/path/\d+|||CUSTOM_PATH
\b[A-Z]{3,}_\d+\b|||IDENTIFIER

See compare_logs.example for more examples. Custom substitutions are applied in addition to the default patterns.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests.

To install this gem onto your local machine, run bundle exec rake install.

Bump versions using rake tasks:

rake version:bump_patch  # x.y.Z
rake version:bump_minor  # x.Y.0
rake version:bump_major  # X.0.0

Generate changelog from git commits:

rake changelog:generate

This gem uses GitHub Actions for:

• CI: Tests on multiple Ruby versions (2.7, 3.0, 3.1, 3.2)
• Auto Release: On merge to main, automatically:
  • Bumps version (patch by default, minor/major via PR labels)
  • Updates changelog
  • Creates GitHub release
  • Publishes to RubyGems

To control version bumps, add labels to your PRs:

• minor - Bump minor version
• major - Bump major version
• No label - Bump patch version (default)

Bug reports and pull requests are welcome on GitHub.

The gem is available as open source under the terms of the MIT License.