ExampleFind
Example post, written to show this format.
Actually Portable Executables
Justine Tunney’s Cosmopolitan libc builds one binary that runs on several operating systems. The essay is the part I keep sending to people.
https://justine.lol/ape.htmlThe page is Actually Portable Executables. It describes a binary format, built with Cosmopolitan libc, that runs on Linux, Mac, Windows, FreeBSD, OpenBSD, and NetBSD without an install step.
I keep coming back to it because most “write once, run anywhere” stories are runtimes. This one is a file. You copy it, you mark it executable or you double-click it, and the same bytes are a program on more than one kernel. The trick is a polyglot header: the file is a shell script, a Windows executable, and a Unix ELF, and each platform reads the part it understands.
That is a ridiculous idea that happens to work, which is my favorite kind of systems work. I do not ship portable executables in my day-to-day, and I am not suggesting anyone replace a normal build. The note I want is the stance. A program can be an artifact you hand to someone. The essay is specific about how the header is laid out, so it is also a good read if you like file formats and you want the mechanism rather than the slogan.