Merge pull request docker#5233 from thaJeztah/nicer_errors

cli: FlagErrorFunc: don't print long usage output for invalid flags

cli/cobra.go

@@ -92,12 +92,8 @@ func FlagErrorFunc(cmd *cobra.Command, err error) error {
 		return nil
 	}
 
-	usage := ""
-	if cmd.HasSubCommands() {
-		usage = "\n\n" + cmd.UsageString()
-	}
 	return StatusError{
-		Status:     fmt.Sprintf("%s\nSee '%s --help'.%s", err, cmd.CommandPath(), usage),
+		Status:     fmt.Sprintf("%s\n\nUsage:  %s\n\nRun '%s --help' for more information", err, cmd.UseLine(), cmd.CommandPath()),
 		StatusCode: 125,
 	}
 }

e2e/cli-plugins/help_test.go

@@ -78,6 +78,6 @@ func TestGlobalHelp(t *testing.T) {
 		})
 		assert.Assert(t, is.Equal(res2.Stdout(), ""))
 		assert.Assert(t, is.Contains(res2.Stderr(), "unknown flag: --badopt"))
-		assert.Assert(t, is.Contains(res2.Stderr(), "See 'docker --help"))
+		assert.Assert(t, is.Contains(res2.Stderr(), "Run 'docker --help' for more information"))
 	})
 }