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.