zlrd — high-performance log viewer CLI (tail/grep alternative)

Fast and memory-efficient log reader and analyzer written in Zig. Designed for working with large log files with support for filtering, search, and real-time streaming.

zlrd is a modern CLI alternative to tail, grep, and basic log viewers.

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✨ Features

• ⚡ Stream large files line-by-line with minimal memory usage
• 🔍 Full-text search (case-insensitive)
• 📊 Filter by log levels (trace, debug, info, warn, error, fatal, panic)
• 📅 Filter logs by date or date range
• 🔄 Real-time mode (tail -f equivalent)
• 📦 Supports JSON and plain text logs
• 🧩 Works with multiple files
• 🗜️ Supports compressed logs (gzip)

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🚀 Install

Requires Zig 0.15.2 or later

git clone https://github.com/alaleks/zlrd.git
cd zlrd
zig build -Doptimize=ReleaseFast
sudo cp zig-out/bin/zlrd /usr/local/bin/

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🧪 Usage

zlrd [options] <file...>

Options:
  -f, --file <path>        Log file (repeatable)
  -s, --search <text>      Search string (case-insensitive)
  -l, --level <levels>     Filter by level (case-insensitive)
                           Values: trace,debug,info,warn,error,fatal,panic
                           Comma-separated: -l error,warn
                           Repeatable:     -l error -l fatal
  -d, --date <date>        Date filter: YYYY-MM-DD or YYYY-MM-DD..YYYY-MM-DD
  -t, --tail               Follow file in real time
  -n, --num-lines <num>    Show last N lines
  -v, --version            Print version and exit
  -h, --help               Show this help

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📌 Examples

# Basic viewing
zlrd app.log
zlrd app.log error.log

# Filter by level
zlrd -l error app.log
zlrd -l error,warn app.log
zlrd -l error -l fatal app.log

# Search (like grep)
zlrd -s "connection failed" app.log

# Date filter
zlrd -d 2024-01-20 app.log
zlrd -d 2024-01-01..2024-01-31 app.log

# Tail mode (real-time)
zlrd -t app.log
zlrd -t -l error -s "timeout" app.log

# Combine filters
zlrd -l error -d 2024-01-20 -s timeout app.log

# Last N lines
zlrd -n 100 app.log

# Short flags (GNU-style)
zlrd -tl error app.log

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🧾 Supported Log Formats

zlrd automatically detects log format:

• JSON logs

  {"level":"error","message":"..."}

• Plain text logs

  [ERROR] something failed
  level=error msg="..."
  severity=error ...
  

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🗺️ Roadmap

• Compressed logs (gzip)
• Aggregates log rows.
• Regex pattern matching
• Advanced time range filtering

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🤝 Contributing

• Follow Zig style guidelines
• Add tests for new features
• Keep the code simple and efficient

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🏷️ Keywords

log viewer, log analyzer, cli tool, tail alternative, grep alternative, zig cli, log parser, log monitoring, developer tools

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📄 License

MIT — see LICENSE for details.