# lttng-regenerate

## NAME



           lttng-regenerate - Manage an LTTng tracing session's data
           regeneration
    


## SYNOPSIS



           Regenerate the metadata of a session:
    
           **lttng**[_GENERAL OPTIONS_] **regenerate metadata**[**--session** =_SESSION_]
    
           Regenerate the state dump of a session:
    
           **lttng**[_GENERAL OPTIONS_] **regenerate statedump**[**--session** =_SESSION_]
    


## DESCRIPTION



           The **lttng regenerate** command regenerates specific data of a
           tracing session.
    
           As of this version, the **metadata** and **statedump** actions are
           available.
    
       **Regenerating a tracing session’s metadata**
           The **lttng regenerate metadata** action can be used to resample the
           offset between the system’s monotonic clock and the wall-clock
           time.
    
           This action is meant to be used to resample the wall-clock time
           following a major NTP
           <https://en.wikipedia.org/wiki/Network_Time_Protocol> correction.
           As such, a system booting with an incorrect wall time can be
           traced before its wall time is NTP-corrected. Regenerating the
           tracing session’s metadata ensures that trace viewers can
           accurately determine the events time relative to Unix Epoch.
    
           If you use lttng-rotate(1) or lttng-enable-rotation(1) to make
           tracing session rotations, this action regenerates the current and
           next trace chunks’s metadata files.
    
       **Regenerating a tracing session’s state dump**
           The **lttng regenerate statedump** action can be used to collect
           up-to-date state dump information during the tracing session. This
           is particularly useful in snapshot (see lttng-snapshot(1)) or
           trace file rotation (see lttng-enable-channel(1)) modes where the
           state dump information may be lost.
    


## OPTIONS



           General options are described in lttng(1).
    
           **-s** _SESSION_ , **--session** =_SESSION_
               Regenerate the data of the tracing session named _SESSION_
               instead of the current tracing session.
    
       **Program information**
           **-h** , **--help**
               Show command help.
    
               This option, like lttng-help(1), attempts to launch
               **/usr/bin/man** to view the command’s man page. The path to the
               man pager can be overridden by the **LTTNG_MAN_BIN_PATH**
               environment variable.
    
           **--list-options**
               List available command options.
    


## LIMITATIONS



           The **lttng regenerate metadata** command can only be used on kernel
           and user space tracing sessions (using per-user buffering), in
           non-live mode.
    
           See lttng-enable-channel(1) for more information about buffering
           schemes and lttng-create(1) for more information about the
           different tracing session modes.
    


## ENVIRONMENT VARIABLES



           **LTTNG_ABORT_ON_ERROR**
               Set to 1 to abort the process after the first error is
               encountered.
    
           **LTTNG_HOME**
               Overrides the **$HOME** environment variable. Useful when the user
               running the commands has a non-writable home directory.
    
           **LTTNG_MAN_BIN_PATH**
               Absolute path to the man pager to use for viewing help
               information about LTTng commands (using lttng-help(1) or **lttng**
               **COMMAND --help**).
    
           **LTTNG_SESSION_CONFIG_XSD_PATH**
               Path in which the **session.xsd** session configuration XML schema
               may be found.
    
           **LTTNG_SESSIOND_PATH**
               Full session daemon binary path.
    
               The **--sessiond-path** option has precedence over this
               environment variable.
    
           Note that the lttng-create(1) command can spawn an LTTng session
           daemon automatically if none is running. See lttng-sessiond(8) for
           the environment variables influencing the execution of the session
           daemon.
    


## FILES



           **$LTTNG_HOME/.lttngrc**
               User LTTng runtime configuration.
    
               This is where the per-user current tracing session is stored
               between executions of lttng(1). The current tracing session
               can be set with lttng-set-session(1). See lttng-create(1) for
               more information about tracing sessions.
    
           **$LTTNG_HOME/lttng-traces**
               Default output directory of LTTng traces. This can be
               overridden with the **--output** option of the lttng-create(1)
               command.
    
           **$LTTNG_HOME/.lttng**
               User LTTng runtime and configuration directory.
    
           **$LTTNG_HOME/.lttng/sessions**
               Default location of saved user tracing sessions (see
               lttng-save(1) and lttng-load(1)).
    
           **/usr/local/etc/lttng/sessions**
               System-wide location of saved tracing sessions (see
               lttng-save(1) and lttng-load(1)).
    
               **Note**
    
               **$LTTNG_HOME** defaults to **$HOME** when not explicitly set.
    


## EXIT STATUS



           **0**
               Success
    
           **1**
               Command error
    
           **2**
               Undefined command
    
           **3**
               Fatal error
    
           **4**
               Command warning (something went wrong during the command)
    


## BUGS



           If you encounter any issue or usability problem, please report it
           on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-
           tools>.
    


## RESOURCES



           •   LTTng project website <https://lttng.org>
    
           •   LTTng documentation <https://lttng.org/docs>
    
           •   Git repositories <http://git.lttng.org>
    
           •   GitHub organization <http://github.com/lttng>
    
           •   Continuous integration <http://ci.lttng.org/>
    
           •   Mailing list <http://lists.lttng.org> for support and
               development: **lttng-dev@lists.lttng.org**
    
           •   IRC channel <irc://irc.oftc.net/lttng>: **#lttng** on **irc.oftc.net**
    


## THANKS



           Special thanks to Michel Dagenais and the DORSAL laboratory
           <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal
           for the LTTng journey.
    
           Also thanks to the Ericsson teams working on tracing which helped
           us greatly with detailed bug reports and unusual test cases.
    


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