register_event_command
extern int register_event_command(struct event_command *cmd);
ret = register_event_command(&trigger_hist_cmd);
ret = register_event_command(&trigger_hist_enable_cmd);
ret = register_event_command(&trigger_hist_disable_cmd);
ret = register_event_command(&trigger_snapshot_cmd);
ret = register_event_command(&trigger_stacktrace_cmd);
ret = register_event_command(&trigger_enable_cmd);
ret = register_event_command(&trigger_disable_cmd);
ret = register_event_command(&trigger_traceon_cmd);
ret = register_event_command(&trigger_traceoff_cmd);