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

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