better structure

scripts/issu

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+if [ "$(id -u)" -eq 0 ]; then
+    exit 0
+fi
+
+if [ -n "$SUDO_USER" ]; then
+    exit 0
+fi
+
+if [ "$LOGNAME" != "$USER" ]; then
+    exit 0
+fi
+
+ppid=$(ps -o ppid= -p $$ 2>/dev/null)
+if [ -n "$ppid" ]; then
+    parent_comm=$(ps -o comm= -p "$ppid" 2>/dev/null)
+    if [ "$parent_comm" = "su" ]; then
+        exit 0
+    fi
+fi
+
+exit 1