'\" t
.\"     Title: lttng-regenerate
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 14 June 2021
.\"    Manual: LTTng Manual
.\"    Source: LTTng 2.13.15
.\"  Language: English
.\"
.TH "LTTNG\-REGENERATE" "1" "14 June 2021" "LTTng 2\&.13\&.15" "LTTng Manual"
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.SH "NAME"
lttng-regenerate \- Regenerate specific data of an LTTng recording session
.SH "SYNOPSIS"
.sp
Regenerate the metadata of a recording session:
.sp
.nf
\fBlttng\fR [\fIGENERAL OPTIONS\fR] \fBregenerate metadata\fR [\fB--session\fR=\fISESSION\fR]
.fi
.sp
Regenerate the state dump event records of a recording session:
.sp
.nf
\fBlttng\fR [\fIGENERAL OPTIONS\fR] \fBregenerate statedump\fR [\fB--session\fR=\fISESSION\fR]
.fi
.SH "DESCRIPTION"
.sp
The \fBlttng regenerate\fR command regenerates specific data of:
.PP
With the \fB--session\fR=\fISESSION\fR option
.RS 4
The recording session named
\fISESSION\fR\&.
.RE
.PP
Without the \fB--session\fR option
.RS 4
The current recording session (see
\fBlttng-concepts\fR(7)
to learn more about the current recording session)\&.
.RE
.sp
See \fBlttng-concepts\fR(7) to learn more about recording sessions\&.
.sp
As of this version, the \fBmetadata\fR and \fBstatedump\fR targets are available\&.
.sp
See the \(lqEXAMPLES\(rq section below for usage examples\&.
.SS "Regenerate the metadata of a recording session"
.sp
Use the \fBmetadata\fR target to resample the offset between the monotonic clock and the wall time of the system, and then regenerate the metadata stream files\&.
.sp
More specifically, you may want to resample the wall time following a major NTP <https://en.wikipedia.org/wiki/Network_Time_Protocol> correction\&. As such, LTTng can trace a system booting with an incorrect wall time before its wall time is NTP\-corrected\&. Regenerating the metadata of the selected recording session ensures that trace readers can accurately determine the event record timestamps relative to the Unix epoch\&.
.sp
Note that if you plan to rotate (see \fBlttng-concepts\fR(7) to learn more) the selected recording session, this target only regenerates the metadata stream files of the current and next trace chunks\&.
.if n \{\
.sp
.\}
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBImportant\fR
.ps -1
.br
.RS 4
.sp
You can only use the \fBmetadata\fR target when the selected recording session:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Is not in live mode (\fB--live\fR
option of
\fBlttng-create\fR(1))\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
If it has user space channels, they\(cqre configured to use a per\-user buffering scheme (\fB--buffers-uid\fR
option of
\fBlttng-enable-channel\fR(1))\&.
.sp
See
\fBlttng-concepts\fR(7)
to learn more about channels\&.
.RE
.sp .5v
.RE
.SS "Regenerate the state dump event records of a recording session"
.sp
Use the \fBstatedump\fR target to collect up\-to\-date state dump information and create corresponding event records\&.
.sp
This is particularly useful if the selected recording session is in snapshot mode (\fB--snapshot\fR option of the \fBlttng-create\fR(1) command) or if LTTng rotates trace files for one of its channels (see \fBlttng-concepts\fR(7)): in both cases, the state dump information may be lost\&.
.SH "OPTIONS"
.sp
See \fBlttng\fR(1) for \fIGENERAL OPTIONS\fR\&.
.PP
\fB-s\fR \fISESSION\fR, \fB--session\fR=\fISESSION\fR
.RS 4
Regenerate specific data of the recording session named
\fISESSION\fR
instead of the current recording session\&.
.RE
.SS "Program information"
.PP
\fB-h\fR, \fB--help\fR
.RS 4
Show help\&.
.sp
This option attempts to launch
\fB/usr/bin/man\fR
to view this manual page\&. Override the manual pager path with the
\fBLTTNG_MAN_BIN_PATH\fR
environment variable\&.
.RE
.PP
\fB--list-options\fR
.RS 4
List available command options and quit\&.
.RE
.SH "EXIT STATUS"
.PP
\fB0\fR
.RS 4
Success
.RE
.PP
\fB1\fR
.RS 4
Command error
.RE
.PP
\fB2\fR
.RS 4
Undefined command
.RE
.PP
\fB3\fR
.RS 4
Fatal error
.RE
.PP
\fB4\fR
.RS 4
Command warning (something went wrong during the command)
.RE
.SH "ENVIRONMENT"
.PP
\fBLTTNG_ABORT_ON_ERROR\fR
.RS 4
Set to
\fB1\fR
to abort the process after the first error is encountered\&.
.RE
.PP
\fBLTTNG_HOME\fR
.RS 4
Path to the LTTng home directory\&.
.sp
Defaults to
\fB$HOME\fR\&.
.sp
Useful when the Unix user running the commands has a non\-writable home directory\&.
.RE
.PP
\fBLTTNG_MAN_BIN_PATH\fR
.RS 4
Absolute path to the manual pager to use to read the LTTng command\-line help (with
\fBlttng-help\fR(1)
or with the
\fB--help\fR
option) instead of
\fB/usr/bin/man\fR\&.
.RE
.PP
\fBLTTNG_SESSION_CONFIG_XSD_PATH\fR
.RS 4
Path to the directory containing the
\fBsession.xsd\fR
recording session configuration XML schema\&.
.RE
.PP
\fBLTTNG_SESSIOND_PATH\fR
.RS 4
Absolute path to the LTTng session daemon binary (see
\fBlttng-sessiond\fR(8)) to spawn from the
\fBlttng-create\fR(1)
command\&.
.sp
The
\fB--sessiond-path\fR
general option overrides this environment variable\&.
.RE
.SH "FILES"
.PP
\fB$LTTNG_HOME/.lttngrc\fR
.RS 4
Unix user\(cqs LTTng runtime configuration\&.
.sp
This is where LTTng stores the name of the Unix user\(cqs current recording session between executions of
\fBlttng\fR(1)\&.
\fBlttng-create\fR(1)
and
\fBlttng-set-session\fR(1)
set the current recording session\&.
.RE
.PP
\fB$LTTNG_HOME/lttng-traces\fR
.RS 4
Default output directory of LTTng traces in local and snapshot modes\&.
.sp
Override this path with the
\fB--output\fR
option of the
\fBlttng-create\fR(1)
command\&.
.RE
.PP
\fB$LTTNG_HOME/.lttng\fR
.RS 4
Unix user\(cqs LTTng runtime and configuration directory\&.
.RE
.PP
\fB$LTTNG_HOME/.lttng/sessions\fR
.RS 4
Default directory containing the Unix user\(cqs saved recording session configurations (see
\fBlttng-save\fR(1)
and
\fBlttng-load\fR(1))\&.
.RE
.PP
\fB/usr/local/etc/lttng/sessions\fR
.RS 4
Directory containing the system\-wide saved recording session configurations (see
\fBlttng-save\fR(1)
and
\fBlttng-load\fR(1))\&.
.RE
.if n \{\
.sp
.\}
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.RS 4
.sp
\fB$LTTNG_HOME\fR defaults to the value of the \fBHOME\fR environment variable\&.
.sp .5v
.RE
.SH "EXAMPLES"
.PP
\fBExample\ \&1.\ \&Regenerate the metadata of the current recording session\&.\fR
.RS 4
.sp
.if n \{\
.RS 4
.\}
.nf
$ lttng regenerate metadata
.fi
.if n \{\
.RE
.\}
.RE
.PP
\fBExample\ \&2.\ \&Regenerate the state dump event records of a specific recording session\&.\fR
.RS 4
.sp
See the \fB--session\fR option\&.
.sp
.if n \{\
.RS 4
.\}
.nf
$ lttng regenerate statedump \-\-session=my\-session
.fi
.if n \{\
.RE
.\}
.RE
.SH "RESOURCES"
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
LTTng project website <https://lttng.org>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
LTTng documentation <https://lttng.org/docs>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
LTTng bug tracker <https://bugs.lttng.org>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Git repositories <https://git.lttng.org>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
GitHub organization <https://github.com/lttng>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Continuous integration <https://ci.lttng.org/>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Mailing list <https://lists.lttng.org/>
for support and development:
\fBlttng-dev@lists.lttng.org\fR
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
IRC channel <irc://irc.oftc.net/lttng>:
\fB#lttng\fR
on
\fBirc.oftc.net\fR
.RE
.SH "COPYRIGHT"
.sp
This program is part of the LTTng\-tools project\&.
.sp
LTTng\-tools is distributed under the GNU General Public License version\ \&2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>\&. See the \fBLICENSE\fR <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file for details\&.
.SH "THANKS"
.sp
Special thanks to Michel Dagenais and the DORSAL laboratory <http://www.dorsal.polymtl.ca/> at \('Ecole Polytechnique de Montr\('eal for the LTTng journey\&.
.sp
Also thanks to the Ericsson teams working on tracing which helped us greatly with detailed bug reports and unusual test cases\&.
.SH "SEE ALSO"
.sp
\fBlttng\fR(1), \fBlttng-concepts\fR(7)