Check for sbin in $PATH

wireguard-install.sh

@@ -60,6 +60,13 @@ This version of CentOS is too old and unsupported"
 	exit
 fi
 
+# Detect environments where $PATH does not include the sbin directories
+if ! grep -q sbin <<< $PATH; then
+	echo '$PATH does not include sbin
+Try using "su -" instead of "su"'
+	exit
+fi
+
 systemd-detect-virt -cq
 is_container="$?"