From riyazdf's review

Prior to this patch, if we provide a value to the output flag, we
write both to the file as well as stdout which is not consistent
with the flag description and also not the intended.

Signed-off-by: Hu Keping <[email protected]>

cmd/notary/util.go

@@ -12,7 +12,7 @@ func getPayload(t *tufCommander) ([]byte, error) {
 
 	// Reads from the given file
 	if t.input != "" {
-		// Please be noticed that ReadFile will cut off the size if it was over 1e9.
+		// Please note that ReadFile will cut off the size if it was over 1e9.
 		// Thus, if the size of the file exceeds 1GB, the over part will not be
 		// loaded into the buffer.
 		payload, err := ioutil.ReadFile(t.input)
@@ -33,17 +33,15 @@ func getPayload(t *tufCommander) ([]byte, error) {
 // feedback is a helper function to print the payload to a file or STDOUT or keep quiet
 // due to the value of flag "quiet" and "output".
 func feedback(t *tufCommander, payload []byte) error {
-	// We only get here when everythings goes well, since the flag "quiet" was
+	// We only get here when everything goes well, since the flag "quiet" was
 	// provided, we output nothing but just return.
 	if t.quiet {
 		return nil
 	}
 
 	// Flag "quiet" was not "true", that's why we get here.
 	if t.output != "" {
-		if err := ioutil.WriteFile(t.output, payload, 0644); err != nil {
-			return err
-		}
+		return ioutil.WriteFile(t.output, payload, 0644)
 	}
 
 	os.Stdout.Write(payload)