cmd/stepd: Serve a named directory

Closes #8

cmd/stepd/main.go

@@ -41,15 +41,22 @@ func main () {
 		flagErrorDocument,
 		flagDirectories,
 		cli.NewHelp())
+	cmd.Syntax = "[OPTIONS]... [DIRECTORY]"
 	cmd.ParseOrExit(os.Args)
-	if len(cmd.Args) > 0 {
-		cmd.Usage()
-		os.Exit(1)
-	}
 	
 	log.Println(`==========| STEP |===========`)
 	log.Println(`Scriptable Template Processor`)
 	log.Println(`... initializing`)
+
+	// the single argument is for the directory to serve. we actually cd
+	// there.
+	if len(cmd.Args) == 1 {
+		err := os.Chdir(cmd.Args[0])
+		if err != nil { log.Fatalln("XXX", err) }
+	} else if len(cmd.Args) > 1 {
+		cmd.Usage()
+		os.Exit(1)
+	}
 	
 	// set up the environment
 	environment := step.Environment { }
@@ -97,7 +104,7 @@ func main () {
 	
 	log.Printf("(i) listening on %s\n", httpServer.Addr)
 	if err := manager.Run(ctx); err != nil && !errors.Is(err, context.Canceled) {
-		log.Fatalln(err)
+		log.Fatalln("XXX", err)
 	}
 }