From 22505cd2a1f6006c50a90999561463eba57897de Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Tue, 15 Apr 2014 20:05:56 -0400
Subject: [PATCH] cmd/pack: print error along with usage

My cmd/go got in a weird state where it started invoking pack grcP.
Change pack to print a 1-line explanation of the usage problem
before the generic usage message.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/87770047
---
 src/cmd/pack/pack.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/cmd/pack/pack.go b/src/cmd/pack/pack.go
index ce73164171..468104deb6 100644
--- a/src/cmd/pack/pack.go
+++ b/src/cmd/pack/pack.go
@@ -52,6 +52,8 @@ func main() {
 	log.SetPrefix("pack: ")
 	// need "pack op archive" at least.
 	if len(os.Args) < 3 {
+		log.Print("not enough arguments")
+		fmt.Fprintln(os.Stderr)
 		usage()
 	}
 	setOp(os.Args[1])
@@ -75,6 +77,8 @@ func main() {
 		ar = archive(os.Args[2], os.O_RDONLY, os.Args[3:])
 		ar.scan(ar.extractContents)
 	default:
+		log.Printf("invalid operation %q", os.Args[1])
+		fmt.Fprintln(os.Stderr)
 		usage()
 	}
 	if len(ar.files) > 0 {
-- 
2.50.0