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Why tailr?

Logs are noisy. tailr makes them readable at a glance:

• Level highlighting — INFO, WARN, ERROR, FATAL, DEBUG, TRACE get distinct colors.
• Keyword highlighting — error, failed, exception, traceback, panic pop in bright red.
• Timestamp coloring — dates and times are dimmed so the signal stands out.
• Live follow — watch logs grow in real time, just like tail -f.
• Filter on the fly — regex grep, or filter by log level.
• Zero dependencies — pure Python stdlib. No install drama, no bloat.

Install

pip install tailr

Or run without installing:

pipx run tailr --help

Via Docker:

docker run --rm ghcr.io/dsk-dev-ai/tailr --help

Usage

# Colorize a log file (last 10 lines)
tailr app.log

# Follow a growing log live
tailr -f app.log

# Follow with more history
tailr -f -n 200 app.log

# Filter by log level
tailr -l ERROR app.log

# Grep with a regex, live
tailr -f -g "kafka|redis" app.log

# Pipe anything in
docker logs -f app | tailr
kubectl logs -f pod | tailr
journalctl -f | tailr -l WARN

Options

Flag	Description
-f, --follow	Keep tailing appended lines (like tail -f)
-n, --lines N	Show N lines from the end (default 10)
-g, --grep REGEX	Only show lines matching a regex
-l, --level LVL	Only show lines with this level (ERROR, WARN, …)
--version	Print version

Colors

INFO      -> blue
DEBUG     -> gray
WARN      -> orange
ERROR     -> red
FATAL     -> magenta
TRACE     -> gray
keywords  -> bright red + bold
timestamps-> dim

Set NO_COLOR=1 to disable colorization, or FORCE_COLOR=1 to force it.

How it works

tailr streams lines and applies a lightweight ANSI colorizer powered by a few small regexes — no external parsing libs, no heuristics beyond the log shape. It respects isatty() to avoid spewing escape codes into pipelines.

Tests

python -m pytest

Tested on Python 3.8–3.12 via GitHub Actions.

Sponsor

Enjoy tailr? Keep it free and dependency-free by becoming a sponsor on GitHub 💜.

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