Other Mini Languages

  [Arithmetic]    arith-context Where legacy arithmetic is allowed
                  sh-numbers    0xFF  0755  etc.
                  sh-arith      1 + 2*3   a *= 2
                  sh-logical    !a && b
                  sh-bitwise    ~a ^ b
  [Boolean]       dbracket      [[ vs. the test builtin
                  bool-expr       [[ ! $x && $y || $z ]]
                                test ! $x -a $y -o $z
                  bool-infix    [[ $a -nt $b ]]  [[ $x == $y ]]
                  bool-path     [[ -d /etc ]]
                  bool-str      [[ -z '' ]]
                  bool-other    [[ -o errexit ]]
  [Patterns]      glob-pat      *.py
                  extglob       ,(*.py|*.sh)
                  regex         [[ foo =~ [a-z]+ ]]
  [Other Sublang] braces        {alice,bob}@example.com
                  histsub       !$  !!  !n
                  char-escapes  \t  \c  \x00  \u03bc
