Added ability to read file by line

src/main.rs

@@ -1,3 +1,16 @@
-fn main() {
-    println!("Hello, world!");
+use std::fs::File;
+use std::io::prelude::*;
+use std::env;
+
+fn main() -> std::io::Result<()>  {
+    let args: Vec<String> = env::args().collect();
+    
+    let filename = &args[1];
+    
+    let mut file = File::open(filename).expect("cannot open file.");
+    let mut contents = String::new();
+    file.read_to_string(&mut contents).expect("unreadable file.");
+
+    println!("{}", contents);
+    Ok(())
 }

test

@@ -0,0 +1 @@
+this is a test