informIT: UNIX to Linux Porting: Project Considerations

“Application porting refers to the process of taking a software
application that runs on one operating system and hardware
architecture, recompiling (making changes as necessary), and
enabling it to run on another operating system and hardware
architecture. In some cases, porting software from one platform to
another may be as straightforward as recompiling and running
verification tests on the ported application. In other cases,
however, it is not as straightforward. Some large applications that
were written for older versions of operating systems and compiled
with native compilers may not adhere to present language standards
and will be more difficult to port, requiring the full attention of
project management…”