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The ternary if-then-else operator generally has the following syntax: E ? X : Y where E is a Boolean expression and if true, the statement is assigned the value Y.
True or False?
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trace-cmd-start(1) [centos man page]


trace-cmd-start - start the Ftrace Linux kernel tracer without recording SYNOPSIS
trace-cmd start [OPTIONS] DESCRIPTION
The trace-cmd(1) start enables all the Ftrace tracing the same way trace-cmd-record(1) does. The difference is that it does not run threads to create a trace.dat file. This is useful just to enable Ftrace and you are only interested in the trace after some event has occurred and the trace is stopped. Then the trace can be read straight from the Ftrace pseudo file system or can be extracted with trace-cmd-extract(1). OPTIONS
The options are the same as trace-cmd-record(1), except that it does not take options specific to recording (-s, -o, -F, -N, and -t). SEE ALSO
trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-reset(1), trace-cmd-split(1), trace-cmd-list(1), trace-cmd-listen(1) AUTHOR
Written by Steven Rostedt, <[1]> RESOURCES
git:// COPYING
Copyright (C) 2010 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL). NOTES
1. 06/11/2014 TRACE-CMD-START(1)

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trace-cmd-extract - extract out the data from the Ftrace Linux tracer. SYNOPSIS
trace-cmd extract [OPTIONS] DESCRIPTION
The trace-cmd(1) extract is usually used after trace-cmd-start(1) and trace-cmd-stop(1). It can be used after the Ftrace tracer has been started manually through the Ftrace pseudo file system. The extract command creates a trace.dat file that can be used by trace-cmd-report(1) to read from. It reads the kernel internal ring buffer to produce the trace.dat file. OPTIONS
-p plugin Although extract does not start any traces, some of the plugins require just reading the output in ASCII format. These are the latency tracers, since the latency tracers have a separate internal buffer. The plugin option is therefore only necessary for the wakeup, wakeup-rt, irqsoff, preemptoff and preemptirqsoff plugins. With out this option, the extract command will extract from the internal Ftrace buffers. -O option If a latency tracer is being extracted, and the -p option is used, then there are some Ftrace options that can change the format. This will update those options before extracting. To see the list of options see trace-cmd-list. To enable an option, write its name, to disable the option append the characters no to it. For example: noprint-parent will disable the print-parent option that prints the parent function in printing a function event. -o outputfile By default, the extract command will create a trace.dat file. This option will change where the file is written to. SEE ALSO
trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1), trace-cmd-stop(1), trace-cmd-reset(1), trace-cmd-split(1), trace-cmd-list(1), trace-cmd-listen(1) AUTHOR
Written by Steven Rostedt, <[1]> RESOURCES
git:// COPYING
Copyright (C) 2010 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL). NOTES
1. 06/11/2014 TRACE-CMD-EXTRACT(1)

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