dpidc: give usage upon unknown operation

1 files changed, 3 insertions, 1 deletions

diff --git a/dpid/dpidc.c b/dpid/dpidc.c
index f4accaf2..54fa3b0a 100644
--- a/dpid/dpidc.c
+++ b/dpid/dpidc.c
@@ -95,7 +95,9 @@ int main(int argc, char *argv[])
        bzero(buffer,256);
        fgets(buffer,255,stdin);
     } else {
-       MSG_ERR("main: Unknown operation '%s'\n", argv[1]);
+       MSG_ERR("main: Unknown operation '%s'\n"
+               "Usage:\n"
+               "%s {stop|register|chat}\n\n", argv[1], argv[0]);
        exit(1);
     }