Colorby

Colorby is a Python program that makes it easier to understand interleaved log lines by coloring each line based on a matching part.

Example:

# Color some logs from systemd based on service name
$ journalctl _COMM=systemd --since -20m | grep '\.service' | colorby '\S+\.service'
Jun 07 14:36:03 iroh systemd[1]: Starting NetworkManager-dispatcher.service - Network Manager Script Dispatcher Service...
Jun 07 14:36:03 iroh systemd[1]: Started NetworkManager-dispatcher.service - Network Manager Script Dispatcher Service.
Jun 07 14:36:13 iroh systemd[1]: NetworkManager-dispatcher.service: Deactivated successfully.
Jun 07 14:37:59 iroh systemd[1]: Starting packagekit.service - PackageKit Daemon...
Jun 07 14:37:59 iroh systemd[1]: Started packagekit.service - PackageKit Daemon.
Jun 07 14:37:59 iroh systemd[1]: Starting flatpak-system-helper.service - flatpak system helper...
Jun 07 14:37:59 iroh systemd[1]: Started flatpak-system-helper.service - flatpak system helper.
Jun 07 14:43:09 iroh systemd[1]: packagekit.service: Deactivated successfully.
Jun 07 14:43:09 iroh systemd[1]: packagekit.service: Consumed 1.177s CPU time, 120.1M memory peak.
Jun 07 14:47:59 iroh systemd[1]: flatpak-system-helper.service: Deactivated successfully.
Jun 07 14:51:10 iroh systemd[1]: Starting fprintd.service - Fingerprint Authentication Daemon...
Jun 07 14:51:10 iroh systemd[1]: Started fprintd.service - Fingerprint Authentication Daemon.
Jun 07 14:51:40 iroh systemd[1]: fprintd.service: Deactivated successfully.

Note how this makes it easier to identify the lines corresponding to each service despite their interleaving.

(If you’re reading this on GitHub, you won’t see the colors. Read it on lumeh.org instead!)

For one-off uses, I recommend running the tool via uvx or pipx:

$ uvx colorby --help
usage: colorby [mode options] [other options] [REGEX]

Color each line from stdin based on its key identified by REGEX.
[…]

For more regular use, install the package using your preferred Python package manager.