I was glad to have the Python equivalent of the shlex crate, which understands shell quoting, helping in transforming command arguments into what's suitable to send to process::Command::args. This allows one to avoid the pain experienced by naively doing the following:

let mut command = command.split(char::is_whitespace);
std::process::Command::new(command.next().unwrap())
    .args(command)
    .spawn()
...

If the command is something like hg commit --message 'git eat world', then the iterator would expand to:

• hg
• commit
• --message
• 'git
• eat
• world'

That will not run, and will fail with a not-obvious error message. Using shlex, we instead:

let mut command = shlex::split(command).unwrap());
std::process::Command::new(command.remove(0).unwrap())
    .args(command)
    .spawn()
 ...

Output should then be like:

• hg
• commit
• --message
• git eat world