'\" t
.\"     Title: lttng-clear
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2 April 2020
.\"    Manual: LTTng Manual
.\"    Source: LTTng 2.12.3
.\"  Language: English
.\"
.TH "LTTNG\-CLEAR" "1" "2 April 2020" "LTTng 2\&.12\&.3" "LTTng Manual"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
lttng-clear \- Clear a tracing session
.SH "SYNOPSIS"
.sp
.nf
\fBlttng\fR [\fIGENERAL OPTIONS\fR] \fBclear\fR [\fISESSION\fR | \fB--all\fR]
.fi
.SH "DESCRIPTION"
.sp
The \fBlttng clear\fR command clears one or more tracing sessions, that is, it deletes the contents of their tracing buffers and all their local and streamed trace data\&.
.sp
If no options are specified, the current tracing session is cleared (see \fBlttng-create\fR(1) for more information about the current tracing session)\&.
.sp
If \fISESSION\fR is specified, the existing tracing session named \fISESSION\fR is cleared\&.
.sp
With the \fB--all\fR option, \fBall\fR the tracing sessions, as listed in the output of \fBlttng list\fR (see \fBlttng-list\fR(1)), are cleared\&.
.sp
If a tracing session is configured in snapshot mode (see the \fBlttng-create\fR(1) command\(cqs \fB--snapshot\fR option), only the tracing buffers are cleared\&.
.sp
For a given tracing session, if at least one rotation occurred (see \fBlttng-rotate\fR(1)), only its tracing buffers and its current trace chunk are cleared; its archived trace chunks are NOT cleared\&.
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
The \fB--disallow-clear\fR option and the \fBLTTNG_RELAYD_DISALLOW_CLEAR\fR environment variable of \fBlttng-relayd\fR(8) can disable remote clearing operations\&. If LTTng sends tracing data over the network for \fISESSION\fR (or for any tracing session with the \fB--all\fR option) to a relay daemon configured as such, \fBlttng clear\fR fails\&.
.sp .5v
.RE
.SH "OPTIONS"
.sp
General options are described in \fBlttng\fR(1)\&.
.SS "Target"
.PP
\fB-a\fR, \fB--all\fR
.RS 4
Clear all the tracing sessions instead of the current tracing session or the tracing session named
\fISESSION\fR\&.
.RE
.SS "Program information"
.PP
\fB-h\fR, \fB--help\fR
.RS 4
Show command help\&.
.sp
This option, like
\fBlttng-help\fR(1), attempts to launch
\fB/usr/bin/man\fR
to view the command\(cqs man page\&. The path to the man pager can be overridden by the
\fBLTTNG_MAN_BIN_PATH\fR
environment variable\&.
.RE
.PP
\fB--list-options\fR
.RS 4
List available command options\&.
.RE
.SH "ENVIRONMENT VARIABLES"
.PP
\fBLTTNG_ABORT_ON_ERROR\fR
.RS 4
Set to 1 to abort the process after the first error is encountered\&.
.RE
.PP
\fBLTTNG_HOME\fR
.RS 4
Overrides the
\fB$HOME\fR
environment variable\&. Useful when the user running the commands has a non\-writable home directory\&.
.RE
.PP
\fBLTTNG_MAN_BIN_PATH\fR
.RS 4
Absolute path to the man pager to use for viewing help information about LTTng commands (using
\fBlttng-help\fR(1)
or
\fBlttng COMMAND --help\fR)\&.
.RE
.PP
\fBLTTNG_SESSION_CONFIG_XSD_PATH\fR
.RS 4
Path in which the
\fBsession.xsd\fR
session configuration XML schema may be found\&.
.RE
.PP
\fBLTTNG_SESSIOND_PATH\fR
.RS 4
Full session daemon binary path\&.
.sp
The
\fB--sessiond-path\fR
option has precedence over this environment variable\&.
.RE
.sp
Note that the \fBlttng-create\fR(1) command can spawn an LTTng session daemon automatically if none is running\&. See \fBlttng-sessiond\fR(8) for the environment variables influencing the execution of the session daemon\&.
.SH "FILES"
.PP
\fB$LTTNG_HOME/.lttngrc\fR
.RS 4
User LTTng runtime configuration\&.
.sp
This is where the per\-user current tracing session is stored between executions of
\fBlttng\fR(1)\&. The current tracing session can be set with
\fBlttng-set-session\fR(1)\&. See
\fBlttng-create\fR(1)
for more information about tracing sessions\&.
.RE
.PP
\fB$LTTNG_HOME/lttng-traces\fR
.RS 4
Default output directory of LTTng traces\&. This can be overridden with the
\fB--output\fR
option of the
\fBlttng-create\fR(1)
command\&.
.RE
.PP
\fB$LTTNG_HOME/.lttng\fR
.RS 4
User LTTng runtime and configuration directory\&.
.RE
.PP
\fB$LTTNG_HOME/.lttng/sessions\fR
.RS 4
Default location of saved user tracing sessions (see
\fBlttng-save\fR(1)
and
\fBlttng-load\fR(1))\&.
.RE
.PP
\fB/etc/lttng/sessions\fR
.RS 4
System\-wide location of saved tracing sessions (see
\fBlttng-save\fR(1)
and
\fBlttng-load\fR(1))\&.
.RE
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
\fB$LTTNG_HOME\fR defaults to \fB$HOME\fR when not explicitly set\&.
.sp .5v
.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 "BUGS"
.sp
If you encounter any issue or usability problem, please report it on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>\&.
.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
.\}
Git repositories <http://git.lttng.org>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
GitHub organization <http://github.com/lttng>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Continuous integration <http://ci.lttng.org/>
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Mailing list <http://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 "COPYRIGHTS"
.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-create\fR(1), \fBlttng-rotate\fR(1), \fBlttng-set-session\fR(1), \fBlttng-relayd\fR(8), \fBlttng\fR(1)