> how can I test - at runtime - under which OS (Linux, Windows and so on)
> a FPC-program is running?
{$IFDEF unix}
http://www.freepascal.org/docs-html/rtl/baseunix/fpuname.html
{$ELSE}
{IFDEF WIN32}
http://msdn.microsoft.com/library/en-us/sysinfo/base/getversionex.asp
{$ENDIF}
{$ENDIF}