How to run shell commands with multiple pipes in it

[Ankitr19]

I have a use case where I need to run shell commands with multiple pipes in it, for example -

dscl . -read "/Users/#{username}" accountPolicyData |grep passwordLastSetTime -A1 |tail -1| cut -d '>' -f 2 | cut -d '<' -f 1 | cut -d . -f 1

This is used for getting the last password change of a user, now if I pass these as args it doesn't work, what's the best way for this?

[Darksonn]

To do this, you have to create each process separately. To set up the pipes, you need to set the stdout of each to piped, then convert the ChildStdout object to a Stdio object that you use as the stdin of the next child.

There's an example of how to do it in this test:

tokio/tests-integration/tests/process_stdio.rs

Lines 146 to 192 in 96370ba

	async fn pipe_from_one_command_to_another() {
	let mut first = cat().spawn().expect("first cmd");
	let mut third = cat().spawn().expect("third cmd");
	// Convert ChildStdout to Stdio
	let second_stdin: Stdio = first
	.stdout
	.take()
	.expect("first.stdout")
	.try_into()
	.expect("first.stdout into Stdio");
	// Convert ChildStdin to Stdio
	let second_stdout: Stdio = third
	.stdin
	.take()
	.expect("third.stdin")
	.try_into()
	.expect("third.stdin into Stdio");
	let mut second = cat()
	.stdin(second_stdin)
	.stdout(second_stdout)
	.spawn()
	.expect("first cmd");
	let msg = "hello world! please pipe this message through";
	let mut stdin = first.stdin.take().expect("first.stdin");
	let write = async move { stdin.write_all(msg.as_bytes()).await };
	let mut stdout = third.stdout.take().expect("third.stdout");
	let read = async move {
	let mut data = String::new();
	stdout.read_to_string(&mut data).await.map(|_| data)
	};
	let (read, write, first_status, second_status, third_status) =
	join!(read, write, first.wait(), second.wait(), third.wait());
	assert_eq!(msg, read.expect("read result"));
	write.expect("write result");
	assert!(first_status.expect("first status").success());
	assert!(second_status.expect("second status").success());
	assert!(third_status.expect("third status").success());
	}