Written 25 Aug 2026. This is a how-to, not a product card. Buy links are not tagged yet.

Back up the leftover-box folder every week without remembering

After one manual USB (or second-box) copy works, let the leftover box run the same rsync on a weekly timer. A phone reminder is still fine if you prefer.

A reminder on your phone is enough if you like it. This note is the later step: the leftover box runs the same backup command every week without you remembering.

Skip until one manual backup worked

If the USB copy or the second-box copy from a backup of the leftover-box folder has not worked once, stop. Fix that first. A timer will not help a copy that does not work yet. The share that copy is for is a file share on the leftover box.

What a timer is

A timer is a schedule on the leftover box. systemd is how Debian and Ubuntu already keep Samba running. A systemd timer wakes up a small backup job once a week. You are not sitting there to type rsync. If you already like cron, a weekly crontab line can run the same script. A timer is the leftover-box way.

Put the rsync in a small script

The leftover box should run one small script, not a raw rsync pasted into a timer. Put it in ~/bin/backup-share.sh. Use the same rsync that already worked in a backup of the leftover-box folder.

Many first-timers plug a USB disk in, copy, and unplug. That is still the honest backup. A timer only copies when that disk is mounted. If you yank it most of the week, keep the phone reminder. If the USB stays plugged in, the script checks the mount, copies if it is there, and quietly exits if it is not, so a missing disk is not an error.

A second leftover computer on the house network is the other path. No USB to forget. Same rsync as first-backup's second option.

Make a folder for small scripts:

mkdir -p ~/bin ~/.config/systemd/user

Write the USB script. Trailing slashes still matter, same as the manual copy:

tee ~/bin/backup-share.sh <<'EOF' #!/bin/sh if ! mountpoint -q /mnt/backup; then exit 0 fi rsync -a /srv/share/ /mnt/backup/share/ EOF

Make it runnable:

chmod +x ~/bin/backup-share.sh

If you copy to another leftover computer instead, drop the mount check and use that rsync from first-backup. The leftover box has to log into the other box without typing a password. That is log in with a key, not the password every time, done from this leftover box to the other one, not from your laptop.

Leave the USB plugged in if this is the USB script. The leftover-box user has to be able to write into that backup folder, the same as the copy you already ran.

A service and a weekly timer

These two small files live in your leftover-box home. The service is the job. The timer is the weekly wake-up. Debian and Ubuntu leftover boxes after the first weekend already know systemctl from Samba.

The leftover box is usually sitting there with nobody SSH'd in. Your personal timers only run while you are logged in, unless you tell it to keep yours running after you log out. That is lingering. One command, then the weekly copy still happens from the couch.

The job:

tee ~/.config/systemd/user/backup-share.service <<'EOF' [Unit] Description=Backup leftover-box share [Service] Type=oneshot ExecStart=%h/bin/backup-share.sh EOF

The weekly wake-up. Sunday at 3 in the morning. If the leftover box was off then, it still runs the copy when it comes back:

tee ~/.config/systemd/user/backup-share.timer <<'EOF' [Unit] Description=Weekly leftover-box share backup [Timer] OnCalendar=Sun 03:00 Persistent=true [Install] WantedBy=timers.target EOF

Keep yours running after you log out. Swap youruser for the leftover-box login:

sudo loginctl enable-linger youruser

Turn the timer on:

systemctl --user daemon-reload

systemctl --user enable --now backup-share.timer

Check

See the timer:

systemctl --user list-timers

You should see backup-share.timer. Run the job once without waiting for Sunday:

systemctl --user start backup-share.service

Then look at the backup folder. Same files as the manual copy. If the USB was unplugged, the script did nothing, and that is correct. Plug it in, mount it the way a backup of the leftover-box folder taught you, and start the service again.

What next

A dedicated file box is still later: a first file box (NAS). Do not buy one for this. If overnight writes worry you, you do not need a UPS yet. A blink is a reboot. You can run the copy again.

Skip

• Skip this note if the manual copy has not worked once, or if a phone reminder is enough.
• Skip restic and Borg on day one.
• Skip a cloud plan.
• Skip buying a NAS.
• Skip RAID.
• Skip leaving the USB plugged in forever without a mount check.