In order to port software to a new platform: - Choose a SYSTEMTYPE name for the new system. You must use a name that includes at least the major version of the operating system (such as SUNOS4 or LINUX2), so that different releases of the same system can be supported without confusion. - Add a case statement to the "makedefs" shell script in the source code top-level directory that recognizes the new system reliably, and that emits the right system-specific information. Be sure to make the code robust against user PATH settings; if the system offers multiple UNIX flavors (e.g. BSD and SYSV) be sure to build for the native flavor, instead of the emulated one. - Add an "#ifdef SYSTEMTYPE" section to the central util/sys_defs.h include file. You may have to invent new feature macro names. Please choose sensible feature macro names such as HAS_DBM or FIONREAD_IN_SYS_FILIO_H. I strongly recommend against using "#ifdef SYSTEMTYPE" in individual source files. While this may look like the quickest solution, it will create a mess when newer versions of the same SYSTEMTYPE need to be supported. You're likely to end up placing "#ifdef" sections all over the source code again.