fix bug where initial lines were not being written

src/main.rs

@@ -94,7 +94,8 @@ fn try_main() -> Result<(), Box<dyn Error>> {
             break;
         }
         let mut out_file = File::create(format!("{}{}", prefix, suffix))?;
-        for _ in 0..opts.lines {
+        out_file.write_all(line.as_bytes())?;
+        for _ in 1..opts.lines {
             line.clear();
             match reader.read_line(&mut line)? {
                 0 => {
@@ -105,6 +106,7 @@ fn try_main() -> Result<(), Box<dyn Error>> {
                 }
             };
         }
+        line.clear();
     }
 
     // see if there's anything left for the remainder file