cli: Make sure to add --help flag for subcommands. (#3773)

--help is now back and prints properly with command
help template.

cmd/main.go

@@ -104,6 +104,10 @@ func registerApp() *cli.App {
 	registerCommand(updateCmd)
 
 	// Set up app.
+	cli.HelpFlag = cli.BoolFlag{
+		Name:  "help, h",
+		Usage: "Show help.",
+	}
 	app := cli.NewApp()
 	app.Name = "Minio"
 	app.Author = "Minio.io"
@@ -111,6 +115,8 @@ func registerApp() *cli.App {
 	app.Usage = "Cloud Storage Server."
 	app.Description = `Minio is an Amazon S3 compatible object storage server. Use it to store photos, videos, VMs, containers, log files, or any blob of data as objects.`
 	app.Flags = globalFlags
+	app.HideVersion = true     // Hide `--version` flag, we already have `minio version`.
+	app.HideHelpCommand = true // Hide `help, h` command, we already have `minio --help`.
 	app.Commands = commands
 	app.CustomAppHelpTemplate = minioHelpTemplate
 	app.CommandNotFound = func(ctx *cli.Context, command string) {

cmd/server-main.go

@@ -79,7 +79,6 @@ EXAMPLES:
       $ export MINIO_SECRET_KEY=miniostorage
       $ {{.HelpName}} http://192.168.1.11/mnt/export/ http://192.168.1.12/mnt/export/ \
           http://192.168.1.13/mnt/export/ http://192.168.1.14/mnt/export/
-
 `,
 }
 

cmd/update-main.go

@@ -46,7 +46,7 @@ var updateCmd = cli.Command{
    {{.HelpName}} - {{.Usage}}
 
 USAGE:
-   {{.HelpName}} {{if .VisibleFlags}}[FLAGS]{{end}}
+   {{.HelpName}}{{if .VisibleFlags}} [FLAGS]{{end}}
 {{if .VisibleFlags}}
 FLAGS:
   {{range .VisibleFlags}}{{.}}
@@ -56,8 +56,10 @@ EXIT STATUS:
    1 - New update is available.
   -1 - Error in getting update information.
 
-VERSION:
-  ` + Version + `{{"\n"}}`,
+EXAMPLES:
+   1. Check if there is a new update available:
+       $ {{.HelpName}}
+`,
 }
 
 const releaseTagTimeLayout = "2006-01-02T15-04-05Z"

cmd/version-main.go

@@ -29,10 +29,15 @@ var versionCmd = cli.Command{
    {{.HelpName}} - {{.Usage}}
 
 USAGE:
-   {{.HelpName}}
-
-VERSION:
-  ` + Version + `{{"\n"}}`,
+   {{.HelpName}}{{if .VisibleFlags}} [FLAGS]{{end}}
+{{if .VisibleFlags}}
+FLAGS:
+  {{range .VisibleFlags}}{{.}}
+  {{end}}{{end}}
+EXAMPLES:
+   1. Prints server version:
+       $ {{.HelpName}}
+`,
 }
 
 func mainVersion(ctx *cli.Context) {