contents/using-lttng/controlling-tracing/saving-loading-tracing-session.md

   1 ---
   2 id: saving-loading-tracing-session
   3 ---
   4
   5 Configuring a tracing session may be long: creating and enabling
   6 channels with specific parameters, enabling kernel and user space
   7 domain events with specific log levels and filters, adding context
   8 to some channels, etc. If you're going to use LTTng to solve real
   9 world problems, chances are you're going to have to record events using
  10 the same tracing session setup over and over, modifying a few variables
  11 each time in your instrumented program or environment. To avoid
  12 constant tracing session reconfiguration, the `lttng` tool is able to
  13 save and load tracing session configurations to/from XML files.
  14
  15 To save a given tracing session configuration, do:
  16
  17 <pre class="term">
  18 lttng save my-session
  19 </pre>
  20
  21 where `my-session` is the name of the tracing session to save. Tracing
  22 session configurations are saved to `~/.lttng/sessions` by default;
  23 use the `--output-path` option to change this destination directory.
  24
  25 All configuration parameters are saved:
  26
  27   * tracing session name
  28   * trace data output path
  29   * channels with their state and all their parameters
  30   * context information added to channels
  31   * events with their state, log level and filter
  32   * tracing activity (started or stopped)
  33
  34 To load a tracing session, simply do:
  35
  36 <pre class="term">
  37 lttng load my-session
  38 </pre>
  39
  40 or, if you used a custom path:
  41
  42 <pre class="term">
  43 lttng load --input-path /path/to/my-session.lttng
  44 </pre>
  45
  46 Your saved tracing session is restored as if you just configured
  47 it manually.