umask [ -S ] [ mask ]
       The umask is set to mask.  mask can be either an octal number or a
       symbolic value as described in the chmod(1) man page.  If mask is
       omitted, the current value is printed.  The -S option causes the
       mask to be printed as a symbolic value.  Otherwise, the mask is
       printed as an octal number.  Note that in the symbolic form the
       permissions you specify are those which are to be allowed (not
       denied) to the users specified.
