[Service]
# keep original `ExecStart=/usr/bin/paccache -r` while adding to the list
# because I want the default behavior and also remove all uninstalled pacman package cache
# may need `sudo systemctl daemon-reload` afterward
# if I want to clear the list first, I should do a line of `ExecStart=` first
# more about drop-in dir see `man systemd.unit`, more about ExecStart see `man systemd.service`
# https://wiki.archlinux.org/title/Systemd#Drop-in_files
# https://wiki.archlinux.org/title/Systemd#Examples
ExecStart=/usr/bin/paccache -ruk0