logmerger: Browse Multiple Logs on a Shared Timeline

Overview

logmerger is a Python command-line utility for reading several log files as one timeline. Instead of switching between files to reconstruct what happened, users can inspect events from each source side by side in a terminal interface or produce merged output for further review.

It is aimed at developers and operators diagnosing incidents across multiple components. It also handles related formats such as compressed text logs, CSV, JSONL, and experimental PCAP input, and can attach untimestamped continuation lines such as tracebacks to the preceding timestamped entry.

Key Features

• Interleaves entries from multiple files according to their timestamps.
• Provides a browsable terminal UI, enabled by default, with interactive help.
• Writes merged output to stdout or a file, including Markdown output for .md files.
• Exports merged log data to CSV.
• Supports common timestamp layouts and custom timestamp formats.
• Filters output by start and end times, including relative time windows.
• Reads text logs, gzip-compressed logs, CSV, JSONL, and experimental PCAP files.
• Offers options for inline output, line numbers, and ignoring lines without timestamps.

Use Cases

• Developers investigating a request that generated entries in several service logs can compare events in timestamp order.
• Operators diagnosing a production incident can narrow multiple log files to a specific time window.
• Engineers reviewing rotated, compressed, or structured logs can bring supported inputs into one view.
• Teams documenting an investigation can export the merged timeline to a file or CSV for later analysis.

Project Facts

• Language: Python
• License: MIT
• Stars: 261
• Forks: 13
• Topics: none listed
• Archived: no

Getting Started

Install from PyPI and pass the log files to the command:

pip install logmerger
logmerger app.log worker.log

See the README for supported timestamp formats, options, and PCAP installation details.

Considerations

• Merging depends on timestamps that match a supported or user-supplied format. Check the README if your logs use a different convention.
• PCAP support is explicitly experimental and requires the optional logmerger[pcap] installation.
• The project is a terminal utility, so its main interactive experience is a text-based UI rather than a graphical log viewer.
• The provided project information does not specify performance limits or guarantees for very large files.