add systemd setup for tarsnap

systemd/tarsnap.service

@@ -0,0 +1,12 @@
+# 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

systemd/tarsnap.timer

@@ -0,0 +1,17 @@
+# systemctl enable /path/to/this/unit-file
+
+[Unit]
+Description=Run tarsnap.service every six hours
+Requires=tarsnap.service
+
+[Timer]
+Unit=tarsnap.service
+OnCalendar=*-*-* 00:00:00
+OnCalendar=*-*-* 06:00:00
+OnCalendar=*-*-* 12:00:00
+OnCalendar=*-*-* 18:00:00
+RandomizedDelaySec=3m
+AccuracySec=1s
+
+[Install]
+WantedBy=timers.target