¬ just serendipity 🍀 (not just serendipity)

tailspin:

tailspin works by reading through a log file line by line, running a series of regexes against each line. The regexes recognize patterns you expect to find in a logfile, like dates, numbers, severity keywords and more.

tailspin does not make any assumptions on the format or position of the items it wants to highlight. For this reason, it requires no configuration and the highlighting will work consistently across different logfiles.

The binary name is tspin(1), not tailspin(1) (confusing!). MacOS has an existing /usr/bin/tailspin binary, which appears to be kernel-related.

It supports -f (--follow), just like tail(1). In fact, you can think of tspin -f as a drop-in replacement for tail -f.

It is available in most package managers.

It supports custom highlight rules (groups) via a ~/.config/tailspin file.

Usage:

# against a log file
% tspin -f /var/log/system.log

# against a command
% kubectl logs mypod -n myns -f | tspin

# built-in highlighters showcase
% echo "2025-01-01 hello null true false 42 https://example.com?param1=foo&param2=bar ERROR WARNING WARN INFO 127.0.0.1 /etc/passwd foo='bar'"  | tspin

It’s possible to add one-off highlighters from the command line (note: case sensitive).

% tspin --highlight=red:err,error,fail --highlight=green:success,ok