X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/cc556a86ae6a83ba4cf5b7125fbabe704207ae60..cc952178056bf6d29471f6986306fb673dcf394a:/lib/cmd/cmd.go

diff --git a/lib/cmd/cmd.go b/lib/cmd/cmd.go
index 353167e800..9292ef7e5f 100644
--- a/lib/cmd/cmd.go
+++ b/lib/cmd/cmd.go
@@ -36,8 +36,9 @@ func (v Version) RunCommand(prog string, args []string, stdin io.Reader, stdout,
 	return 0
 }
 
-// Multi is a Handler that looks up its first argument in a map, and
-// invokes the resulting Handler with the remaining args.
+// Multi is a Handler that looks up its first argument in a map (after
+// stripping any "arvados-" or "crunch-" prefix), and invokes the
+// resulting Handler with the remaining args.
 //
 // Example:
 //
@@ -52,19 +53,15 @@ func (v Version) RunCommand(prog string, args []string, stdin io.Reader, stdout,
 type Multi map[string]Handler
 
 func (m Multi) RunCommand(prog string, args []string, stdin io.Reader, stdout, stderr io.Writer) int {
-	if len(args) < 1 {
-		fmt.Fprintf(stderr, "usage: %s command [args]\n", prog)
-		m.Usage(stderr)
-		return 2
-	}
 	_, basename := filepath.Split(prog)
-	if strings.HasPrefix(basename, "arvados-") {
-		basename = basename[8:]
-	} else if strings.HasPrefix(basename, "crunch-") {
-		basename = basename[7:]
-	}
+	basename = strings.TrimPrefix(basename, "arvados-")
+	basename = strings.TrimPrefix(basename, "crunch-")
 	if cmd, ok := m[basename]; ok {
 		return cmd.RunCommand(prog, args, stdin, stdout, stderr)
+	} else if len(args) < 1 {
+		fmt.Fprintf(stderr, "usage: %s command [args]\n", prog)
+		m.Usage(stderr)
+		return 2
 	} else if cmd, ok = m[args[0]]; ok {
 		return cmd.RunCommand(prog+" "+args[0], args[1:], stdin, stdout, stderr)
 	} else {