tailjlogs 2.4.0

A terminal log file viewer with enhanced JSONL support - based on Toolong

TailJLogs

Based on Textualize/toolong by Will McGugan

A terminal application to view, tail, merge, and search log files with enhanced JSONL support.

What's New in v2.4

• Log Summary Mode: New --summary flag to scan and summarize log files
  • Groups rotated log files by base name (e.g., app.001.jsonl, app.002.jsonl → app)
  • Reports first/last log timestamps, timespan, and log level counts
  • Supports JSON output with --json flag
  • Recursive/non-recursive directory scanning with -r/--no-recursive

What's New in v2.1

• Merged File Tailing: Now you can tail multiple merged files simultaneously (Ctrl+T)
• Filename Prefix in Merged View: Each line shows a colored filename prefix (docker-compose style)
• Glob Pattern Support: Use wildcards like *.jsonl, logs/**/*.log
• Directory Expansion: Pass a directory to automatically find all log files

What's New in v2.0

TailJLogs v2.0 is a complete rewrite based on the excellent Toolong project by Will McGugan. Key enhancements:

• JSONL Compact Format: JSONL logs display in a readable format: 01-15T09:36:38.194 INFO module 39 : message
• Separate Filter Dialog (\ key): Hide non-matching lines (vs Find which highlights matches)
• Full TUI Experience: Navigate with arrow keys, view detailed JSON with Enter
• Updated for Textual 7.x: Modern async terminal UI

Features

• 📋 Live tailing of log files (single or merged)
• 🎨 Syntax highlights common web server log formats
• ⚡ Fast - opens multi-gigabyte files instantly
• 📝 Enhanced JSONL support: Compact formatted display + pretty-printed detail view
• 📦 Opens .bz and .bz2 files automatically
• 🔀 Merge & tail multiple files with colored filename prefixes
• 🔍 Find (/ or Ctrl+F): Highlight matching lines
• 🔎 Filter (\): Show only matching lines
• 📁 Glob patterns: *.jsonl, logs/**/*.log, directories
• 📊 Summary mode: Scan directories and report log statistics

Installation

# Using pip
pip install tailjlogs

# Using uv (recommended)
uv tool install tailjlogs

# Using pipx
pipx install tailjlogs

Update

# Using pip
pip install --upgrade tailjlogs
# Using uv
uv tool update tailjlogs
# Using pipx
pipx upgrade tailjlogs

After installation, use either tailjlogs or tl command.

Usage

# View a log file
tailjlogs /path/to/logfile.jsonl
tl /path/to/logfile.jsonl

# View multiple files (opens in tabs)
tl access.log error.log app.jsonl

# Merge multiple files by timestamp
tl --merge access.log error.log app.jsonl

# Glob patterns
tl *.jsonl                    # All .jsonl files
tl logs/**/*.log              # Recursive glob
tl /var/log/myapp/            # Directory (finds all log files)

# Merge and tail (docker-compose style output)
tl --merge *.jsonl
# Then press Ctrl+T to start tailing

# Summary mode - scan and report log statistics
tl --summary .                     # Current directory
tl --summary /var/log/myapp/       # Specific directory
tl --summary logs/ --json          # Output as JSON
tl --summary logs/ --no-recursive  # Don't search subdirectories

Summary Mode Output

📁 api_v2
------------------------------------------------------------
   Files: 2
          - api_v2.jsonl
          - rotation/api_v2.001.jsonl
   Total Lines: 2,360

   First Log: 2026-01-31 04:49:56
   Last Log:  2026-02-01 08:01:47
   Timespan:  1d 3h 11m 51s

   Level Range: DEBUG to INFO
   Level Counts:
      DEBUG      :    1,579
      INFO       :      781

Merged View with Filename Prefix

When viewing merged files, each line shows a colored filename prefix:

db_monitor      │ 01-15T09:36:38.194 INFO  cache   15 : Cache hit
error           │ 01-15T09:36:38.200 ERROR api     42 : Connection failed
db_monitor      │ 01-15T09:36:38.210 DEBUG db      89 : Query executed

Keyboard Shortcuts

Navigation

Key	Action
↑/↓ or w/s or k/j	Move up/down a line
←/→ or h/l	Scroll left/right
Page Up/Page Down or Space	Next/previous page
Home or G	Jump to start
End or g	Jump to end (press twice to tail)
m/M	Advance +1/-1 minutes
o/O	Advance +1/-1 hours
d/D	Advance +1/-1 days

Features

Key	Action
/ or Ctrl+F	Find - highlight matching lines
\	Filter - show only matching lines
Enter	Toggle pointer mode / View JSON detail
Ctrl+L	Toggle line numbers
Ctrl+T	Tail current file
?	Show help
Ctrl+C or q	Exit

JSONL Format

TailJLogs displays JSONL log entries in a compact format:

01-15T09:36:38.194 INFO     auth                  42 : User logged in
01-15T09:36:39.521 WARNING  api                  156 : Rate limit approaching
01-15T09:36:40.003 ERROR    database             89 : Connection timeout

Press Enter on any line to see the full JSON object, pretty-printed.

Expected JSONL fields:

{
  "timestamp": "2025-01-15T09:36:38.194Z",
  "level": "INFO",
  "message": "User logged in",
  "module": "auth",
  "line": 42
}

Development

git clone https://github.com/brianoflondon/tailjlogs.git
cd tailjlogs
uv sync
uv run tailjlogs --help

Credits

This project is based on Toolong by Will McGugan and the Textualize team. Built with Textual.

License

MIT License - see LICENSE for details.

Original Toolong: Copyright (c) 2024 Will McGugan This fork: Copyright (c) 2025 Brian of London