std::process::Command cannot run hdiutil on macOS (mount failed - No such file or directory) but the command works fine when run in the terminal - macos

Question

hdiutils, when fed a correct path to a valid file, returns error 2, no such file or directory. When I join the indices of the command array with " ", print them, copy them and run the exact string in a terminal, it works fine.
This is the function edited to contain only the relevant bits. In order to reproduce my error, you will need a disk image located at ~/Downloads/StarUML.dmg.
use std::env;
use std::fs;
use std::process::Command;
fn setup_downloads(download_name: &str) {
let downloads_path: String = {
if cfg!(unix) {
//these both yield options to unwrap
let path = env::home_dir().unwrap();
let mut downloads_path = path.to_str().unwrap().to_owned();
downloads_path += "/Downloads/";
downloads_path
} else {
"we currently only support Mac OS".to_string()
}
};
let files_in_downloads =
fs::read_dir(&downloads_path).expect("the read_dir that sets files_in_downloads broke");
let mut file_path: String = "None".to_string();
for file_name in files_in_downloads {
let file_name: String = file_name
.expect("the pre string result which sets file_name has broken")
.file_name()
.into_string()
.expect("the post string result which sets file_name has broken")
.to_owned();
if file_name.contains(&download_name) {
file_path = format!("'{}{}'", &downloads_path, &file_name);
}
}
let len = file_path.len();
if file_path[len - 4..len - 1] == "dmg".to_string() {
let mount_command = ["hdiutil", "mount"];
let output = Command::new(&mount_command[0])
.arg(&mount_command[1])
.arg(&file_path)
.output()
.expect("failed to execute mount cmd");
if output.status.success() {
println!(
"command successful, returns: {}",
String::from_utf8_lossy(&output.stderr).into_owned()
);
} else {
println!(
"command failed, returns: {}",
String::from_utf8_lossy(&output.stderr).into_owned()
);
}
}
}
fn main() {
setup_downloads(&"StarUML".to_string());
}

Answer 1

Split your Command into a variable and print it using the debugging formatter after you have specified the arguments:
let mut c = Command::new(&mount_command[0]);
c
.arg(&mount_command[1])
.arg(&file_path);
println!("{:?}", c);
This outputs
"hdiutil" "mount" "\'/Users/shep/Downloads/StarUML.dmg\'"
Note that Command automatically provides quoting for each argument, but you have added your own set of single quotes:
format!("'{}{}'", &downloads_path, &file_name);
// ^ ^
Remove these single quotes.