display help page on unknown commands (#176)

* display help page on unknown commands

* point user to --help page instead of printing the whole page

* make grammar make sense

* linting

pkg/cmd/root.go

@@ -5,6 +5,7 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
@@ -53,7 +54,18 @@ func Execute() {
 	rootCmd.SetUsageTemplate(getUsageTemplate())
 	rootCmd.SetVersionTemplate(version.Template)
 	if err := rootCmd.Execute(); err != nil {
-		fmt.Println(err)
+		if strings.Contains(err.Error(), "unknown command") {
+			suggestions := rootCmd.SuggestionsFor(os.Args[1])
+			suggStr := "\nS"
+			if len(suggestions) > 0 {
+				suggStr = fmt.Sprintf(" Did you mean \"%s\"?\nIf not, s", suggestions[0])
+			}
+			fmt.Println(fmt.Sprintf("Unknown command \"%s\" for \"%s\".%s"+
+				"ee \"stripe --help\" for a list of available commands.",
+				os.Args[1], rootCmd.CommandPath(), suggStr))
+		} else {
+			fmt.Println(err)
+		}
 		os.Exit(1)
 	}
 }