echo -e '\xHH' now outputs a byte whose hexadecimal value is HH,
for compatibility with bash.
+ ls has a new --hide=PATTERN option that behaves like
+ --ignore=PATTERN, except that it is overridden by -a or -A.
+ This can be useful for aliases, e.g., if lh is an alias for
+ "ls --hide='*~'", then "lh -A" lists the file "README~".
+
In the following cases POSIX allows the default GNU behavior,
so when POSIXLY_CORRECT is set: