LOGSWAN(1)

🦢 NAME

okay bestie, meet logswan — she's a fast Web log analyzer that runs on probabilistic data structures ✨ like she's literally that girl.

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📜 SYNOPSIS

logswan [-ghv] [-d db] logfile

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💖 DESCRIPTION

So logswan is a fast Web log analyzer using probabilistic data structures, and no I'm not being dramatic, that's literally what she is 💅. She's built for very large log files, like typically APIs logs — the kind of file that makes other tools start sweating 😭.

Here's the iconic part: her memory usage is constant no matter how big the log file is 🫶. Doesn't matter if the log is 10MB or 10TB, she's not out here gobbling RAM. She takes approximatively 4MB of RAM. That's it. That's the whole budget. Queen behavior 👑.

Counting unique visitors? She does that with two HyperLogLog counters — one for IPv4, and another one for IPv6 — and that gives a relative accuracy of 0.10% 🌸. Probabilistic, but make it precise.

Oh and btw, if file is a single dash (`-`), logswan reads from the standard input ✨. Very demure, very stdin-pilled.

The options are as follows:

• -d db — Specify path to a GeoIP database.
• -g — Enable GeoIP lookups.
• -h — Display usage.
• -v — Display version.

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🌈 EXAMPLES

okay so here's a lil script that processes all log files in the current directory and saves the output in a file — it's giving automation, it's giving efficiency, it ate 🔥:

#!/bin/sh
for file in $(ls *.log)
do
        logswan $file > $file.json
done
exit 0

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🎀 AUTHORS

logswan was written by Frederic Cambus. shoutout to the dev fr fr 🫶

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💀 reminder bestie: this page is the Debian build from February 13, 2026. mwah, go analyze some logs, you got this 💖✨🦋🌸💅