LTTng » LTTng-tools

If you were to do:

$ lttng create snaps --snapshot
Session snaps created.
Default snapshot output set to: /home/daniel/lttng-traces/snaps-20130729-143544
Snapshot mode set. Every channel enabled for that session will be set in overwrite mode and mmap output.
$ lttng enable-channel ch0 --buffers-pid -u
UST channel ch0 enabled for session snaps
$ lttng enable-event -a -c ch0 -u
All UST events are enabled in channel ch0
$ lttng start
Tracing started for session snaps
$ /usr/src/lttng-ust-2.3.0-rc1/doc/examples/easy-ust/sample
sample starting
sample done
$ lttng snapshot del-output snapshot
Snapshot output snapshot successfully deleted for session snaps
$ lttng snapshot list-output
Snapshot output list for session snaps
    None
$ lttng snapshot record
Snapshot recorded successfully for session snaps

But of course no actual snapshot is recorded to disc. You should really get an error if you try to snapshot record while no "output" (output parameter set) is defined.