HELP SYS_OS_TYPE                                 Robert Duncan, Apr 1989
                                           Revised John Gibson, Aug 1995

A list of words and numbers giving details of the operating system under
which Poplog is running.

See REF * sys_os_type for a listing of the currently defined values on
different machines and operating systems.

The information in this list actually relates to the system for which
the current version of Poplog was built, and so may not be quite the
same as the system under which it is running. The version number in
particular may be smaller or less precise than you might expect.

sys_os_type is best used to provide just a visual summary of the
operating system type (to be output in messages, for example). If you
are writing a program where the control depends on properties of the
operating system -- perhaps because it only works under Unix, or SunOS,
or whatever -- you are advised instead to use INCLUDE * SYSDEFS (or
LIB * SYSDEFS) to determine the information you need. This library
defines a set of flags and numeric constants which express all the
information present in sys_os_type but in a more comprehensive and
usable form.

One particular problem to watch out for if you do use sys_os_type in a
program, is that any comparison performed on the version number is not
guaranteed to work as expected unless some care is taken: this is due to
the rounding errors which can arise when using floating-point numbers.
The macro DEFV (see HELP * DEFV) used in conjunction with the constants
defined by LIB * SYSDEFS provides a secure way of doing this kind of
test.


See also:

    HELP * SYS_MACHINE_TYPE
    HELP * SYS_PROCESSOR_TYPE
    HELP * SYSDEFS
    HELP * POPHOST

     REF * SYSTEM


--- C.all/help/sys_os_type
--- Copyright University of Sussex 1995. All rights reserved.
