pranaless

Yes and no. While coreutils does provide an echo binary, shells also have a built-in for optimisation purposes.

At first I had the code calling the binary directly, but then changed it to spawning a shell (and so using the builtin). It’s very cursed either way.

use std::process::Command;

fn main() {
    Command::new("sh")
        .arg("-c")
        .arg("echo Hello World!")
        .spawn()
        .unwrap();
}

Like this?

OnceLock is the wrong primitive for this. Use a Mutex or an RwLock instead? You can initialize either of them with an empty array at declaration, so you don’t need the set_log function. In push_log, do a .lock().unwrap() for a mutex or .write().unwrap() for an rwlock to get mutable access to the vector.