NAME
  umask - get or set the file mode creation mask

SYNOPSIS
  umask [-S] [mask]

DESCRIPTION
  The umask utility shall set the file mode creation mask of the current shell
  execution environment (see Shell Execution Environment) to the value specified
  by the mask operand. This mask shall affect the initial value of the file
  permission bits of subsequently created files. If umask is called in a subshell
  or separate utility execution environment, such as one of the following:
  (umask 002)
  nohup umask ...
  find . -exec umask ... \;

  it shall not affect the
  file mode creation mask of the caller's environment.

  If the mask operand is
  not specified, the umask utility shall write to standard output the value of
  the file mode creation mask of the invoking process.

OPERANDS
  mask  A string specifying the new file mode creation mask. The string is
        treated in the same way as the mode operand described in the EXTENDED
        DESCRIPTION section for chmod. For a symbolic_mode value, the new value
        of the file mode creation mask shall be the logical complement of the
        file permission bits portion of the file mode specified by the
        symbolic_mode string.  In a symbolic_mode value, the permissions op
        characters '+' and '-' shall be interpreted relative to the current
        file mode creation mask; '+' shall cause the bits for the indicated
        permissions to be cleared in the mask; '-' shall cause the bits for the
        indicated permissions to be set in the mask.  The interpretation of
        mode values that specify file mode bits other than the file permission
        bits is unspecified.  In the octal integer form of mode, the specified
        bits are set in the file mode creation mask.  The file mode creation
        mask shall be set to the resulting numeric value.  The default output
        of a prior invocation of umask on the same system with no operand also
        shall be recognized as a mask operand.

OPTIONS
  -S  Produce symbolic output.