Do not record if no plugin or event was specified

An new user may just try doing a record and see what happens, and
will be surprised when there is no output to show.

This patch adds an error message if no event or plugin is specified.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/trace-cmd.c b/trace-cmd.c
index 22441b8..52ae03c 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -1191,7 +1191,7 @@ int main (int argc, char **argv)
                         case 'o':
                                 if (!record)
                                         die("start does not take output\n"
-                                            "Did you mean 'record'?\n");
+                                            "Did you mean 'record'?");
                                 if (output)
                                         die("only one output file allowed");
                                 output = optarg;
@@ -1264,6 +1264,9 @@ int main (int argc, char **argv)
                 die("Command start does not take any commands\n"
                     "Did you mean 'record'?");
 
+        if (!events && !plugin)
+                die("no event or plugin was specified... aborting");
+
         if (record) {
                 if (output)
                         output_file = output;