UNIX for Advanced & Expert Users

alias ec=/usr/bin/echo
src> ((1)) && { ec "true"; ((0)) && { ec "deep true"; }; } || { ec "false"; ((1)) && { ec "deep false"; }; }
true
false
deep false

src> if ((1)); then { ec "true"; ((0)) && { ec "deep true"; }; } else { ec "false"; ((1)) && { ec "deep false"; }; } fi
true

src> bash -version
GNU bash, version 2.05.0(1)-release (sparc-sun-solaris2.9)
Copyright 2000 Free Software Foundation, Inc.

((1)) &&                        # True, and forces the next part to be evaluated.
{ ec "true";                    # returns true
  ((0)) && { ec "deep true"; }  # false, so the second part is not evaluated. This
                                # also means that the outer block counts as false
; } ||                          # First part is false ( true && false == false ),
                                # so the second part gets evaluated
{ ec "false";                   # returns true
  ((1)) && { ec "deep false"; } # First part is true, so the second is evaluated too.
; }