'\" t
.\"     Title: trace-cmd-show
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 09/11/2020
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "TRACE\-CMD\-SHOW" "1" "09/11/2020" "\ \&" "\ \&"
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.SH "NAME"
trace-cmd-show \- show the contents of the Ftrace Linux kernel tracing buffer\&.
.SH "SYNOPSIS"
.sp
\fBtrace\-cmd show\fR [\fIOPTIONS\fR]
.SH "DESCRIPTION"
.sp
The trace\-cmd(1) show displays the contents of one of the Ftrace Linux kernel tracing files: trace, snapshot, or trace_pipe\&. It is basically the equivalent of doing:
.sp
.if n \{\
.RS 4
.\}
.nf
cat /sys/kernel/debug/tracing/trace
.fi
.if n \{\
.RE
.\}
.SH "OPTIONS"
.PP
\fB\-p\fR
.RS 4
Instead of displaying the contents of the "trace" file, use the "trace_pipe" file\&. The difference between the two is that the "trace" file is static\&. That is, if tracing is stopped, the "trace" file will show the same contents each time\&.
.sp
.if n \{\
.RS 4
.\}
.nf
The "trace_pipe" file is a consuming read, where a read of the file
will consume the output of what was read and it will not read the
same thing a second time even if tracing is stopped\&. This file
als will block\&. If no data is available, trace\-cmd show will stop
and wait for data to appear\&.
.fi
.if n \{\
.RE
.\}
.RE
.PP
\fB\-s\fR
.RS 4
Instead of reading the "trace" file, read the snapshot file\&. The snapshot is made by an application writing into it and the kernel will perform as swap between the currently active buffer and the current snapshot buffer\&. If no more swaps are made, the snapshot will remain static\&. This is not a consuming read\&.
.RE
.PP
\fB\-c\fR \fIcpu\fR
.RS 4
Read only the trace file for a specified CPU\&.
.RE
.PP
\fB\-f\fR
.RS 4
Display the full path name of the file that is being displayed\&.
.RE
.PP
\fB\-B\fR \fIbuf\fR
.RS 4
If a buffer instance was created, then the
\fB\-B\fR
option will access the files associated with the given buffer\&.
.RE
.PP
\fB\-\-tracing_on\fR
.RS 4
Show if tracing is on for the given instance\&.
.RE
.PP
\fB\-\-current_tracer\fR
.RS 4
Show what the current tracer is\&.
.RE
.PP
\fB\-\-buffer_size\fR
.RS 4
Show the current buffer size (per\-cpu)
.RE
.PP
\fB\-\-buffer_total_size\fR
.RS 4
Show the total size of all buffers\&.
.RE
.PP
\fB\-\-ftrace_filter\fR
.RS 4
Show what function filters are set\&.
.RE
.PP
\fB\-\-ftrace_notrace\fR
.RS 4
Show what function disabled filters are set\&.
.RE
.PP
\fB\-\-ftrace_pid\fR
.RS 4
Show the PIDs the function tracer is limited to (if any)\&.
.RE
.PP
\fB\-\-graph_function\fR
.RS 4
Show the functions that will be graphed\&.
.RE
.PP
\fB\-\-graph_notrace\fR
.RS 4
Show the functions that will not be graphed\&.
.RE
.PP
\fB\-\-cpumask\fR
.RS 4
Show the mask of CPUs that tracing will trace\&.
.RE
.SH "SEE ALSO"
.sp
trace\-cmd(1), trace\-cmd\-record(1), trace\-cmd\-report(1), trace\-cmd\-start(1), trace\-cmd\-extract(1), trace\-cmd\-reset(1), trace\-cmd\-split(1), trace\-cmd\-list(1), trace\-cmd\-listen(1)
.SH "AUTHOR"
.sp
Written by Steven Rostedt, <\m[blue]\fBrostedt@goodmis\&.org\fR\m[]\&\s-2\u[1]\d\s+2>
.SH "RESOURCES"
.sp
git://git\&.kernel\&.org/pub/scm/linux/kernel/git/rostedt/trace\-cmd\&.git
.SH "COPYING"
.sp
Copyright (C) 2010 Red Hat, Inc\&. Free use of this software is granted under the terms of the GNU Public License (GPL)\&.
.SH "NOTES"
.IP " 1." 4
rostedt@goodmis.org
.RS 4
\%mailto:rostedt@goodmis.org
.RE