improving usage warnings for di-maker

diff --git a/di-maker b/di-maker
index 5e377d80be6f9c2200dd8749efc5034100985f5f..86b34b2047d5ff8c34ee590d2adc186c0c6d773e 100755 (executable)
--- a/di-maker
+++ b/di-maker
@@ -21,7 +21,7 @@ ARCH=${ARCH:-amd64}
 DISTRO=${DISTRO:-debian}
 
 if [ -z "$output" ] ; then
-    printf "you must specify a file name for the image to be built" >&2
+    printf "Usage: di-maker ISOFILE [FILE ...]\n" >&2
     exit 1
 fi