From cfd894f446f356ed1c0fb37d88aee8c34bb4e40c Mon Sep 17 00:00:00 2001
From: Marco Molteni <marco.molteni@mailbox.org>
Date: Sun, 19 Jan 2020 19:40:53 +0100
Subject: [PATCH] usage: if the program supports subcommands, mention it

---
 example_test.go | 2 +-
 usage.go        | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/example_test.go b/example_test.go
index ea123e4..be3cd12 100644
--- a/example_test.go
+++ b/example_test.go
@@ -193,7 +193,7 @@ func Example_helpTextWithSubcommand() {
 	MustParse(&args)
 
 	// output:
-	// Usage: example [--verbose]
+	// Usage: example [--verbose] <command> [<args>]
 	//
 	// Options:
 	//   --verbose
diff --git a/usage.go b/usage.go
index 57935fd..b07280b 100644
--- a/usage.go
+++ b/usage.go
@@ -88,6 +88,13 @@ func (p *Parser) writeUsageForCommand(w io.Writer, cmd *command) {
 			fmt.Fprint(w, spec.placeholder)
 		}
 	}
+
+	// if the program supports subcommands and the command-line doesn't contain any,
+	// give a hint to the user about the existence of these subcommands.
+	if len(p.cmd.subcommands) > 0 && p.cmd == cmd {
+		fmt.Fprint(w, " <command> [<args>]")
+	}
+
 	fmt.Fprint(w, "\n")
 }