theme-change.md

How to make your terminal reflect system dark/light mode

This is dependent on both your OS as well as your terminal.

On macOS with Kitty

Let's assume the destinations of your kitty color themes are ~/.config/kitty/themes/my-theme-dark.conf and .../my-theme-light.conf respectively. Add the following to your kitty.conf:

include theme.conf

Now we will create a script that (1) sym-links the currently correct theme file to ~/.config/kitty/theme.conf and (2) reloads all running instances of kitty. For this, place the following into a file ~/.config/kitty/sync-theme

#!/bin/zsh

kitty_dir="${0:a:h}"
theme="$kitty_dir/theme.conf"

[[ "$(defaults read -g AppleInterfaceStyle 2>/dev/null)" = "Dark" ]] \
    && target="$kitty_dir/themes/my-theme-dark.conf" \
    || target="$kitty_dir/themes/my-theme-light.conf"

rm -rf "$theme"
ln -s "$target" "$theme"

for pid in "$(ps -x | grep '/Applications/kitty.app/Contents/MacOS/kitty' | grep -v grep | awk '{ print $1 }')"; do
    kill -SIGUSR1 $pid
done

and make this file executable by running chmod +x ~/.config/kitty/sync-theme. With this set up, you can already manually refresh kitty to the correct theme by executing the script.

To make this happen automatically whenever the macOS theme changes, we have to listen to the Distributed Notification AppleInterfaceThemeChangedNotification and call our script whenever this notification is fired. There are lots of ways of doing this! One way is using Hammerspoon, which might be convenient if you (like me) are already using it anyways. To set up the listener with Hammerspoon, add the following to your ~/.hammerspoon/init.lua:

themeWatcher = hs.distributednotifications.new(function(name, object, userInfo)
    os.execute(os.getenv('HOME') .. '/.config/kitty/sync-theme')
end, dn)
themeWatcher:start()

That's it! Now kitty will automatically switch between dark and light mode whenever macOS switches.