FollowSunFree is a lightweight cross-platform C++ application that switches your desktop theme between light and dark modes based on your geographical location and the local solar position (sunrise/sunset times).
Currently implemented and tested with GNOME 42+ on Fedora 42.
FollowSunFree is proudly built with D🌀tName C++ Template.
Download the binary tarball and extract the contents of the bin/ and share/ folders into:
~/.local/bin/
~/.local/share/
Then set it up to run via systemd (user scope) for automatic switching:
systemctl --user daemon-reload
systemctl --user enable followsun.timer
systemctl --user start followsun.timer🛑 To stop automatic switching:
systemctl --user stop followsun.timerSystemd unit files (*.service and *.timer) can be found in the assets directory. Customize them to match your user environment.
📖 See also: systemd.service documentation
⚠️ Currently, you must manually specify the --utc offset based on standard or daylight saving time.
Run the binary with arguments that match your location and preferences.
~/.local/bin/FollowSunFree --lat 50.0755 --lon 14.4378 --utc 120 --riseoffset 60 --setoffset -30Output:
════════════════════ FOLLOW SUN SUMMARY ════════════════════
📅 20.05.2025 08:24:39
📍 Location: 50.0755°N, 14.4378°E
🌐 UTC offset: 2 hours
🌅 Sunrise: 5:08 ➔ 🌆 Sunset: 20:48
User offset adjustments:
Sunrise: +60 min Sunset: -30 min
Theme trigger times:
Light theme at: 6:08 ☀️
Dark theme at: 20:18 🌚
═══════════════════════════════════════════════════════════════| Argument | Short | Type | Default | Description |
|---|---|---|---|---|
--help |
-h |
flag | - | Displays help information |
--log2file |
-2 |
bool | false | Enables logging to a file |
--lat |
double | 0 | Latitude | |
--lon |
double | 0 | Longitude | |
--utc |
int | 0 | UTC offset in minutes | |
--riseoffset |
int | 0 | Sunrise offset in minutes | |
--setoffset |
int | 0 | Sunset offset in minutes | |
--clear |
bool | false | Clears all settings |
FollowSunFree automatically saves your last used arguments to a config file in the assets folder. On subsequent runs, it will use those saved settings unless overridden.
To reset everything:
~/.local/bin/FollowSunFree --clearOr simply run it with new arguments.
- Native support for more desktop environments (e.g., KDE, Windows)
- Automatic detection of UTC offset (daylight saving and standard time)
- Automatic installation of the entire project
- Trigger theme switch immediately after resuming from sleep (no need to wait for the systemd timer trigger)
This template is provided "as is," without any guarantees regarding its functionality or suitability for any purpose.
MIT License
Copyright (c) 2024-2025 Tomáš Mark