#spawn — 10LOC

Bunadvanced

Piped-stdio subprocesses with Bun.spawn

const proc = Bun.spawn(["bun", "-e", "console.log((await Bun.stdin.text()).toUpperCase())"], {
  stdin: "pipe",
});

proc.stdin.write("hello from the parent\n");

Bun.spawn's stdin/stdout are a FileSink and a ReadableStream, so you can write to a child process incrementally and read its output as it streams back.