Lazylog

A fast, minimal, terminal-based log file viewer with vim-like navigation and real-time monitoring.

Lazylog provides instant log file access with structured parsing, smooth scrolling, and efficient handling of large files through memory-mapped I/O.

Features

• Multiple log sources - Support for DYEH file logs, iOS device logs, and Android device logs
• Headless streaming - Dump parsed logs to stdout for scripting and coding agent workflows
• Real-time monitoring - Automatically follows log updates like tail -f
• Vim-like navigation - Use j/k or arrow keys for navigation, h/l for horizontal scrolling
• Smart log parsing - Automatically detects timestamps, log levels, tags, and messages
• Color-coded severity - Visual distinction between DEBUG, INFO, WARN, ERROR, and FATAL levels
• Memory efficient - Handles large files with memory-mapped access and ring buffers (16K capacity)
• Cross-platform - Runs on Linux, macOS, and Windows
• Framework library - lazylog-framework available as a reusable crate for custom log viewers
• Responsive UI - Interruptible sleeps ensure snappy key responses even when no device is connected

Performance

Lazylog is designed for responsiveness:

• Event polling at 16ms interval (~60fps) ensures immediate key and mouse response
• Provider polling at 100ms interval for efficient log ingestion
• Interruptible sleeps check stop signals every 25ms, allowing quit to interrupt long waits
• Immediate stop signaling on quit keys (q or Ctrl+C) triggers fast shutdown

This means pressing q exits within ~25-50ms even when no device is connected (was up to 1s before).

Installation

Homebrew

# Install
brew install tr-nc/tap/lazylog

# Upgrade
brew upgrade lazylog

# Uninstall
brew uninstall lazylog

Build from source

git clone https://github.com/tr-nc/lazylog.git
cd lazylog
cargo build --release

# Run the built binary
./target/release/lazylog --help

Usage

Basic usage

# Run lazylog with DYEH preview logs
cargo run -- --dyeh-preview

# Use DYEH editor logs
cargo run -- --dyeh-editor

# Use iOS log provider
cargo run -- --ios

# Use iOS log provider (effect mode)
cargo run -- --ios-effect

# Use Android log provider
cargo run -- --android

# Use Android log provider (effect mode)
cargo run -- --android-effect

# Apply filter on startup
cargo run -- --filter "ERROR"

# Stream logs to stdout without the TUI
cargo run -- --headless --dyeh-preview

Headless mode

Use --headless to skip the TUI and stream logs directly to stdout.

# Headless mode works with filters and all existing providers
cargo run -- --headless --android-effect --filter "ERROR"

# Stream iOS logs non-interactively
cargo run -- --headless --ios

Headless mode behavior:

• Streams forever for live providers until interrupted
• Reuses the existing provider and parser for the selected mode
• Applies startup filters from --filter
• Prints each matching parsed item using its full raw_content

Key bindings

Key	Action
j/k or ↑/↓	Navigate up/down through log items
d	Jump to bottom (newest) log item
h/l or ←/→	Horizontal scrolling (left/right)
Space	Make selected log visible in view
[/]	Decrease/increase detail level (0-4)
/ or f	Enter filter mode
v	Enter visual mode
y	Yank (copy) selected log item(s) to clipboard
a	Yank (copy) all displayed logs to clipboard
c	Clear all logs
w	Toggle text wrapping
m	Toggle mouse capture (disable to select/copy text)
b	Toggle debug logs visibility
1/2/3	Focus logs/details/debug panel
?	Show/hide help popup
Esc	Exit visual mode / Go back / Clear filter
q	Quit
Ctrl+C	Quit
Mouse scroll	Vertical scrolling through logs or focused panel
Shift + Mouse scroll	Horizontal scrolling
Mouse click	Focus panel, select item, or drag scrollbar

Filter mode

• Type to filter logs by content
• Enter - Apply filter and exit filter mode
• Esc - Cancel filter and exit filter mode

Visual mode

• Press v on a log item to start visual selection
• Press j/k to expand or shrink the consecutive selection
• Press y to copy selected log items to the clipboard
• Press Esc to exit visual mode
• Filter mode cannot be entered while visual mode is active
• When multiple log items are selected, the details panel shows a hint instead of item details

Navigation

• Logs panel: Navigate through log items, newest at top (focus with 1)
• Details panel: Shows expanded details for selected log item (focus with 2)
• Debug panel: Shows application debug messages (focus with 3, toggle with b)
• Use mouse click or 1/2/3 to focus different panels and scroll within them

Development

Prerequisites

• Rust toolchain 1.77+ (install via rustup)
• iOS support (optional): Requires idevicesyslog - install via brew install libimobiledevice on macOS
• Android support (optional): Requires adb - install via brew install android-platform-tools on macOS

Build and test

# Check compilation
cargo check

# Format code
cargo fmt

# Build debug version
cargo build

# Build release version
cargo build --release

# Run tests
cargo test

# Run linter
cargo clippy

Publish framework

cargo publish -p lazylog-framework

Contributing

We welcome contributions, testing, and feedback! If you:

• Find bugs - Please report them with terminal environment details
• Test on different terminals - Help us improve compatibility beyond VS Code
• Have feature ideas - Share your suggestions for improvements
• Want to contribute code - Pull requests are welcome

Feel free to open issues or submit pull requests to help make lazylog better for everyone.

Acknowledgments

Inspired by lazygit for the name and terminal UI design philosophy.

Built with ratatui for terminal UI and crossterm for cross-platform terminal handling.

Co-authored and documented with Claude Code.