umask [ -S ] [ mask ]
       The umask is set to mask.  mask can be either an octal number or
       a symbolic value as described in chmod(1).  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 permis-
       sions you specify are those which are to be allowed (not denied)
       to the users specified.