Both of the ones that spring immediately to mind have reservations. Interix, the second POSIX subsystem for Windows NT, already had all of the things that the

Both of the ones that spring immediately to mind have reservations. Interix, the second POSIX subsystem for Windows NT, already had all of the things that the Windows Subsystem for Linux is gradually reinventing, and Microsoft already owns it. * https://news.ycombinator.com/item?id=17773681 https://news.ycombinator.com/item?id=17773681 Some of the softwares involved were in fact open-source. Unfortunately, the SUA Community disappeared years ago, and there is no trace of the software packages that it used to provide. I haven't kept up to date with Blue Lion (ArcaOS) and eComstation; so it is tricky to nominate OS/2.