Pretty much the binary format equivalent of that "single source file that compiles in C++/Pascal/Fortran/COBOL/shell/PHP" trick. While it's interesting in its own right, Hackernews currently thinks it's the future of computing.
Indeed. I am sincerely confused as to why people are so enamored with this.
As I understand it (I haven't actually seen it explained anywhere). It's some kind of a hack that lets a single file be interpreted as both a shell script and a COM file, and a C library that does runtime detection of which OS you are running.
magic pixie dust for x86/amd64 executables which makes them run on bare metal, windows, linux, freebsd, ..., unchanged. it's a giant hack in the best possible meaning of the word.
I'm certainly doing the project a disservice with this, but isn't it "just" basically a file format hack that basically acts as an "if-check" that allows the executable to select an appropriate entry point depending on your OS?
If checks are in the libc functions. (a guess, didn't look at the source)
It's more of a composite header (ELF/PE/etc) like those "it's both a JPG and a zip" things", though.