Eh? The majority of modern POSIXy software runs on at least Linux, Mac OS X, and FreeBSD.

In fact, Mac OS X is the most widely deployed UNIX-like system ever. What you're a claiming to be true probably more applies to Mac OS X than Linux.

I honestly haven't seen a recent package that was accidentally not portable in the long-term across the various modern UNIX-like systems because of confusion of Linux for POSIX.

Have you used FreeBSD? Having played with Free/Open/DragonflyBSD, I came away shocked at how non-portable most software is.

Any examples? Even Debian packages include custom patches.

There are more UNIX flavours than those ones.

Irrelevant, if the vast majority of modern packages work with the big three, it's highly likely they work with other conforming POSIX systems.

The keyword being likely.

I don't miss my days of writing portable POSIX code across DG/UX, Solaris, HP-UX, Aix, FreeBSD, Red-Hat, Debian and the respective #ifdefs.

This is still irrelevant.

You were asserting that the majority of programmers think Linux == UNIX and have never tried to write a portable application.

Thst is clearly false as the majority of programmers probably confuse Mac OS X for UNIX and most modern unix-like software is portable to at least Linux, Mac OS X, and FreeBSD. Portable is more general than "portable across every UNIX that has existed."

Increasing the specificity of your argument mid-way to avoid the incorrectness of your initial general argument isn't very genuine.

But yes, your revised second statement is probably correct: most UNIX programmers have never tried writing portable code across "DG/UX, Solaris, HP-UX, Aix, FreeBSD, Red-Hat, Debian" exactly because there is no practical reason for it.

Other than sell software to enterprise customers.

Sure, you're correct on that. Thanks for staying on topic.