[Unit]
Description=Regenerate grub-btrfs.cfg

[Service]
Type=oneshot
# Set the possible paths for `grub-mkconfig`
Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
# Load environment variables from the configuration
EnvironmentFile=/etc/default/grub-btrfs/config
# If we aren't booted off a snapshot, regenerate just '/boot/grub/grub-btrfs.cfg' if it exists and is not empty, else regenerate the whole grub menu
ExecStart=bash -c 'if [[ -z $(/usr/bin/findmnt -n / | /usr/bin/grep "\.snapshots") ]]; then if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi; fi'