[linguae]

Interestingly enough, Apple did contribute to porting Linux to PowerPC Macs in the mid-1990s under the MkLinux project, which started in 1996 before Apple’s purchase of NeXT later that year:

https://en.m.wikipedia.org/wiki/MkLinux

I don’t think there was any work done on bringing the Macintosh GUI and application ecosystem to Linux. However, until the purchase of NeXT, Apple already had the Macintosh environment running on top of Unix via A/UX (for 68k Macs) and later the Macintosh Application Environment for Solaris and HP-UX; the latter ran Mac OS as a Unix process. If I remember correctly, the work Apple did for creating the Macintosh Application Environment laid the groundwork for Rhapsody’s Blue Box, which later became Mac OS X’s Classic environment. It is definitely possible to imagine the Macintosh Application Environment being ported to MkLinux. The modern FOSS BSDs were also available in 1996, since this was after the settlement of the lawsuit affecting the BSDs.

Of course, running the classic Mac OS as a process on top of Linux, FreeBSD, BeOS, Windows NT, or some other contemporary OS was not a viable consumer desktop OS strategy in the mid 1990s, since this required workstation-level resources at a time when Apple was still supporting 68k Macs (Mac OS 8 ran on some 68030 and 68040 machines). This idea would’ve been more viable in the G3/G4 era, and by the 2000s it would have be feasible to give each classic Macintosh program its own Mac OS process running on top of a modern OS, but I don’t think Apple would have made it past 1998 without Jobs’ return, not to mention that the NeXT purchase brought other important components to the Mac such as Cocoa, IOKit, Quartz (the successor to Display PostScript) and other now-fundamental technologies.

[CharlesW]

> I don’t think there was any work done on bringing the Macintosh GUI and application ecosystem to Linux.

QTML (which became the foundation of the Carbon API) was OS agnostic. The Windows versions of QuickTime and iTunes used QTML, and in an alternate universe Apple could've empowered developers to bring Mac OS apps to Windows and Linux with a more mature version of that technology.

[threeseed]

Completely forget about MkLinux. The timing is fascinating.

MkLinux was released in February 1996 whilst Copland got officially cancelled in August 1996.

So it's definitely conceivable that internally they were considering to just give up on the Copland microkernel and run it all on Linux. And maybe this was a legitimate third option to BeOS and NeXT that was never made public.

[kalleboo]

What's crazy is that MkLinux was actually Linux-on-Mach, not just a baremetal PowerPC Linux. The work they did to port Mach to PowerPC for MkLinux was then reused in the port of NeXTSTEP Mach to PowerPC. Everything was very intertwined.

[masswerk]

Also, MkLinux wasn't that stable. I experimented a bit with it at the time and it wasn't really ripe for production. It kind of worked, but there would have been lots of work to be invested (probably more than Apple could afford) to turn this into a mainstream OS.