Linux SystemD Timers

Moving files to SFTP with systemd timers

Systemd timers give you predictable scheduling, dependency handling, and built-in logging. In this example every .zip found in /data/ is moved to sftp://monitor02@10.0.0.24/target/ with an SSH key that uses a passphrase. The transfer should happen at five minutes past each hour.

1. Capture credentials in an alias

$ connect alias add
Alias name: job1
Endpoint (no folder, e.g. sftp://host or s3://bucket): sftp://monitor02@10.0.0.24
Change scheme-specific settings? (y/N) y
SFTP private key path (optional): /apps/keys/id_ed25519
SFTP key passphrase (optional): ****
Connection test: OK
Alias 'job1' saved. You can now use it as @job1/.. in commands.

Note

Aliases encrypt passphrases inside ~/.connect/connect_aliases.enc, keeping credentials off the process list for systemd-managed units.

2. Verify connectivity and host key

$ connect ls @job1
The key (SHA256:v/goXq57T++lsDmeYduLCRJEUzEqf9u9OybWiHt3VRc) of 10.0.0.24:22 is unknown. Do you want to add this key to known_hosts (y/n): y
Name        Size      ModTime
incoming/   -         2024-11-27T13:39:18Z

Run the command again to ensure the stored host key is trusted without prompting.

3. Prepare the connect move invocation

$ connect move --batch --no-color --parallel 3 \
    \
    /data/*.zip \
    @job1/target/
2024/11/27 15:45:51 INFO Moving files to sftp://monitor02@10.0.0.24/target/

Key options

/data/*.zip selects local files · @job1/target/ reuses the alias · --parallel drives concurrency · --batch --no-color makes journald output easy to parse.

4. Create the systemd service

$ systemctl --user edit --force --full job1.service
[Unit]
Description=SFTP job1 Service
After=network-online.target
Wants=network-online.target

[Service]
ExecStart=/apps/connect move --batch --no-color --parallel 3 /data/*.zip @job1/target/

Note

If systemctl complains about the user bus (Failed to connect to bus: No medium found), log in as the target user directly (ssh apps@host) rather than using su.

5. Create the timer unit

$ systemctl --user edit --force --full job1.timer
[Unit]
Description=Timer for job1 Service

[Timer]
OnCalendar=*:05:00
Persistent=false

[Install]
WantedBy=timers.target

Tip

Use systemd-analyze calendar "*:05:00" --iterations 5 to validate the schedule.

6. Enable and start

$ systemctl --user daemon-reload
$ systemctl --user enable job1.timer
Created symlink /apps/.config/systemd/user/timers.target.wants/job1.timer → /apps/.config/systemd/user/job1.timer.
$ systemctl --user start job1.timer
$ systemctl --user status job1.timer
● job1.timer - Timer for job1 Service
     Loaded: loaded (/apps/.config/systemd/user/job1.timer; enabled; preset: enabled)
     Active: active (waiting) since Thu 2024-11-28 11:49:59 UTC; 27s ago
    Trigger: Thu 2024-11-28 12:05:00 UTC; 14min left
   Triggers: ● job1.service

7. Keep user services running after logout

$ sudo loginctl enable-linger apps