basic-install.sh: fix "install: invalid user ''"

refs #1767

automated install/basic-install.sh

@@ -57,6 +57,10 @@ IPV6_ADDRESS=""
 QUERY_LOGGING=true
 INSTALL_WEB=true
 
+if [ -z "${USER}" ]; then
+  USER="$(id -un)"
+fi
+
 
 # Find the rows and columns will default to 80x24 if it can not be detected
 screen_size=$(stty size 2>/dev/null || echo 24 80)