# systemctl enable /path/to/this/unit-file

[Unit]
Description=Backup documents folder to Tarsnap
Wants=tarsnap.timer

[Service]
ExecStart=/bin/sh -c "/usr/bin/tarsnap -c --print-stats -f \"$(uname -n)-$(date +%%Y-%%m-%%d_%%H-%%M-%%S)\" /home/rob/Documents/"
WorkingDirectory=/root

[Install]
WantedBy=multi-user.target