Rename the script + use systemd timer functionality

wanchecker@.service

@@ -0,0 +1,14 @@
+# Should be placed to /usr/lib/systemd/user/
+
+[Unit]
+Description=WAN IPv4 checker & email sender for dynamic IPv4 server environments
+After=network-online.target
+
+[Service]
+ExecStart=/usr/bin/bash /home/%i/wanchecker.sh
+
+# Emailing fails if this is enabled
+#NoNewPrivileges=true
+
+[Install]
+WantedBy=default.target

wanchecker@.timer

@@ -0,0 +1,14 @@
+# Should be placed to /usr/lib/systemd/user/
+
+# https://wiki.archlinux.org/index.php/Systemd/Timers
+
+[Unit]
+Description=Run WAN IP checker in fixed intervals and on boot
+
+[Timer]
+OnBootSec=2min
+OnUnitActiveSec=20min
+Persistent=true
+
+[Install]
+WantedBy=timers.target

wanip-checker@.service

@@ -1,25 +0,0 @@
-# Should be placed to /usr/lib/systemd/user/
-
-####
-# Usage
-
-# systemctl --user enable wanip-checker@<username>.service && \
-# systemctl --user start wanip-checker@<username>.service && \
-# systemctl --user daemon-reload
-
-[Unit]
-Description=WAN IPv4 checker & email sender for dynamic IPv4 server environments
-After=network-online.target
-
-[Service]
-ExecStart=/usr/bin/bash /home/%i/wanip-checker.sh
-
-# Restart (check) every 20 minutes (1200 seconds)
-RestartSec=1200
-Restart=always
-
-# Emailing fails if this is enabled
-#NoNewPrivileges=true
-
-[Install]
-WantedBy=default.target