check if user exists before creating

Author: rekado

createuser.sh

@@ -1 +1,5 @@
-createuser -S -D -R -U postgres libertree
+if echo "\dg" | psql -U postgres | grep -wq libertree; then
+  echo "User already exists: libertree"
+else
+  createuser -S -D -R -U postgres libertree
+fi