ShellCheck demo

# test.sh

#!/usr/bin/env bash

for n in aaa bbb ccc ; do
  mv $n $n.bak             ## Quoting not required if
done                       ## inputs are known.

for n in ddd/* ; do
  mv "$n" "$n.bak"         ## Quoting *is* required if
done                       ## we don't trust the input.

###

▶ shellcheck test.sh ; echo $?
0