fop(1): committing to Rust error messages

src/fop.rs

@@ -18,7 +18,7 @@
 
 use std::{
 	env::args,
-	io::{ Read, stdin, Write },
+	io::{ Read, stdin, stdout, Write },
 	process::{ Command, exit, Stdio },
 };
 
@@ -54,8 +54,8 @@ fn main() {
 		exit(EX_USAGE);
 	});
 
-	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|_| {
-		eprintln!("{}: {}: Not an integer.", argv[0], argv[1]);
+	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}.", argv[0], argv[1], e);
 		exit(EX_DATAERR);
 	});
 
@@ -74,8 +74,8 @@ fn main() {
 		.stdin(Stdio::piped())
 		.stdout(Stdio::piped())
 		.spawn()
-		.unwrap_or_else( |_| {
-			eprintln!("{}: {}: Command not found.", argv[0], argv[command_arg]);
+		.unwrap_or_else( |e| {
+			eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
 			exit(EX_UNAVAILABLE);
 		});
 
@@ -83,7 +83,7 @@ fn main() {
 		eprintln!(
 			"{}: {}: No such index in input.",
 			argv[0],
-			index.to_string()
+			index.to_string(),
 		);
 		exit(EX_DATAERR);
 	});
@@ -93,11 +93,8 @@ fn main() {
 		drop(child_stdin);
 	}
 
-	let output = spawned.wait_with_output().unwrap_or_else(|_| {
-		eprintln!("{}: {}: Command has no output.",
-			argv[0],
-			argv[command_arg]
-		);
+	let output = spawned.wait_with_output().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
 		exit(EX_IOERR);
 	});
 
@@ -105,16 +102,17 @@ fn main() {
 
 	if replace.pop() != Some(b'\n') { replace = output.stdout; }
 
-	let new_field = String::from_utf8(replace).unwrap_or_else(|_| {
-		eprintln!(
-			"{}: {}: Command output is invalid UTF-8.",
-			argv[0],
-			argv[command_arg]
-		);
+	let new_field = String::from_utf8(replace).unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
 		exit(EX_IOERR);
 	});
 
 	fields[index] = &new_field;
 
-	print!("{}", fields.join(&d.to_string()));
+	stdout().write_all(
+		fields.join(&d.to_string()).as_bytes()
+	).unwrap_or_else(|e|{
+		eprintln!("{}: {}.", argv[0], e);
+		exit(EX_IOERR);
+	});
 }