run(1) works

src/run.rs

@@ -38,23 +38,26 @@ fn error(p: &str, n: &str, e: Error) -> ExitCode {
 }
 
 fn usage(s: &str) -> ExitCode {
-	eprintln!("Usage: {} command [argument...]");
+	eprintln!("Usage: {} command [argument...]", s);
 	ExitCode::from(EX_USAGE as u8)
 }
 
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
-	let mut optind = 0;
+	let mut optind = 1;
 
-	let mut arg0: Option<String> = None;
-	let mut dir = String::from(".");
+	/* arg0 is None if no argv[0] is meant to be given (argc will be 0),
+	 * however I don't know how to do this in Rust, so the option is currently
+	 * meaningless. -z will set this to None. */
+	let mut arg0: Option<String> = Some(String::default());
+	let mut dir = String::from("."); // $PWD for command
 
-	let mut cmd;
-
-	while let Some(opt) = argv.getopt("C:n") {
+	while let Some(opt) = argv.getopt("C:n:z") {
 		match opt.opt() {
+			// Consistent with precedent; git, make, tar, etc.
 			Ok("C") => dir = opt.arg().unwrap(),
 			Ok("n") => arg0 = Some(opt.arg().unwrap()),
+			// Ok("z") => arg0 = None,
 			_ => { return usage(&argv[0]); }
 		}
 		optind = opt.ind();
@@ -62,11 +65,15 @@ fn main() -> ExitCode {
 
 	if argv.len() - optind < 1 { return usage(&argv[0]); }
 
-	cmd = Command::new(argv[optind].clone()).current_dir(argv[1].clone());
+	let mut cmd = Command::new(argv[optind].clone());
+	cmd.current_dir(dir.clone());
 
-	if let Some(a) = arg0 { cmd.arg0(a); }
+	match arg0 {
+		Some(a) if a != String::default() => { cmd.arg0(a); },
+		_ => () // TODO: argv[0]==NULL support
+	}
 
-	if argv.len() - optind > 2 {
+	if argv.len() - optind > 1 { // there are arguments
 		let cmdargs = argv
 			.iter()
 			.clone()
@@ -77,18 +84,16 @@ fn main() -> ExitCode {
 
 	match cmd.spawn() {
 		Ok(mut child) => match child.wait() {
-			Ok(status) => {
-				match status.code() {
-					Some(code) => ExitCode::from(code as u8),
-					None => {
-						eprintln!("{}: {}: process terminated by signal",
-							argv[0], argv[2]);
-						ExitCode::FAILURE
-					}
+			Ok(status) => match status.code() {
+				Some(code) => ExitCode::from(code as u8),
+				None => {
+					eprintln!("{}: {}: process terminated by signal",
+						argv[0], argv[2]);
+					ExitCode::FAILURE
 				}
 			},
-			Err(e) => error(&argv[0], &argv[2], e)
+			Err(e) => error(&argv[0], &argv[optind], e)
 		},
-		Err(e) => error(&argv[0], &argv[2], e)
+		Err(e) => error(&argv[0], &argv[optind], e)
 	}
 }