try out os::exec and pipe

backend/cmd/proctest/main.ha

@@ -0,0 +1,35 @@
+use fmt;
+use io;
+use os::exec;
+use os;
+use strings;
+
+export fn main() void = {
+	let cmd = exec::cmd("./run.sh")!;
+
+	let stdout_pipe = exec::pipe();
+	exec::addfile(&cmd, os::stdout_file, stdout_pipe.1);
+
+	let stderr_pipe = exec::pipe();
+	exec::addfile(&cmd, os::stderr_file, stderr_pipe.1);
+
+	let proc = exec::start(&cmd)!;
+	io::close(stdout_pipe.1)!;
+	io::close(stderr_pipe.1)!;
+
+	let stdout_data = io::drain(stdout_pipe.0)!;
+	io::close(stdout_pipe.0)!;
+
+	let stderr_data = io::drain(stderr_pipe.0)!;
+	io::close(stderr_pipe.0)!;
+
+	let status = exec::wait(&proc)!;
+	let s = exec::exit(&status) as int;
+	fmt::printfln("status: {}", s)!;
+
+	let out = strings::fromutf8(stdout_data) as str;
+	fmt::printfln("stdout:\n{}", out)!;
+
+	let out = strings::fromutf8(stderr_data) as str;
+	fmt::printfln("stderr:\n{}", out)!;
+};

backend/run.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+echo "first line"
+echo "error 1" >&2
+echo "second line"
+echo "error 2" >&2
+echo "third line"
+
+exit 17