lttng.c: show basic help when no arguments are provided

Fixes #1011

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng/lttng.c b/src/bin/lttng/lttng.c
index b498539c76ea7847baafb177f23ee792f50fa901..02903becdab2ca4783b147d3e060063f1e460855 100644 (file)
--- a/src/bin/lttng/lttng.c
+++ b/src/bin/lttng/lttng.c
@@ -242,6 +242,55 @@ end:
        return ret;
 }
 
+static void show_basic_help(void)
+{
+       puts("Usage: lttng [--group=GROUP] [--mi=TYPE] [--no-sessiond | --sessiond-path=PATH]");
+       puts("             [--quiet | -v | -vv | -vvv] COMMAND [COMMAND OPTIONS]");
+       puts("");
+       puts("Available commands:");
+       puts("");
+       puts("Tracing sessions:");
+       puts("  create            " CONFIG_CMD_DESCR_CREATE);
+       puts("  destroy           " CONFIG_CMD_DESCR_DESTROY);
+       puts("  load              " CONFIG_CMD_DESCR_LOAD);
+       puts("  metadata          " CONFIG_CMD_DESCR_METADATA);
+       puts("  save              " CONFIG_CMD_DESCR_SAVE);
+       puts("  set-session       " CONFIG_CMD_DESCR_SET_SESSION);
+       puts("");
+       puts("Channels:");
+       puts("  add-context       " CONFIG_CMD_DESCR_ADD_CONTEXT);
+       puts("  disable-channel   " CONFIG_CMD_DESCR_DISABLE_CHANNEL);
+       puts("  enable-channel    " CONFIG_CMD_DESCR_ENABLE_CHANNEL);
+       puts("");
+       puts("Event rules:");
+       puts("  disable-event     " CONFIG_CMD_DESCR_DISABLE_EVENT);
+       puts("  enable-event      " CONFIG_CMD_DESCR_ENABLE_EVENT);
+       puts("");
+       puts("Status:");
+       puts("  list              " CONFIG_CMD_DESCR_LIST);
+       puts("  status            " CONFIG_CMD_DESCR_STATUS);
+       puts("");
+       puts("Control:");
+       puts("  snapshot          " CONFIG_CMD_DESCR_SNAPSHOT);
+       puts("  start             " CONFIG_CMD_DESCR_START);
+       puts("  stop              " CONFIG_CMD_DESCR_STOP);
+       puts("");
+       puts("Resource tracking:");
+       puts("  track             " CONFIG_CMD_DESCR_TRACK);
+       puts("  untrack           " CONFIG_CMD_DESCR_UNTRACK);
+       puts("");
+       puts("Miscellaneous:");
+       puts("  calibrate         " CONFIG_CMD_DESCR_CALIBRATE);
+       puts("  help              " CONFIG_CMD_DESCR_HELP);
+       puts("  version           " CONFIG_CMD_DESCR_VERSION);
+       puts("  view              " CONFIG_CMD_DESCR_VIEW);
+       puts("");
+       puts("Run `lttng help COMMAND` or `lttng COMMAND --help` to get help with");
+       puts("command COMMAND.");
+       puts("");
+       puts("See `man lttng` for more help with the lttng command.");
+}
+
 /*
  * Parse command line arguments.
  *
@@ -258,6 +307,7 @@ static int parse_args(int argc, char **argv)
        }
 
        if (argc < 2) {
+               show_basic_help();
                clean_exit(EXIT_FAILURE);
        }