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trace-cmd-extract(1) [centos man page]


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)

Check Out this Related Man Page

trace(1)						      General Commands Manual							  trace(1)

       trace - trace system calls of programs

       trace [options] cmd args...

       The  command  with  no flag arguments traces for the given cmd and args all system calls made and prints a time stamp, the PID, call and/or
       return values and arguments and puts its output in the file trace.dump.

       -f filename
	       Puts dump in file filename.

       -z      Echos arguments only.

       Only one of the following option arguments can be specified at one time.

       -c#     Traces given PIDs and their children.  Up to sixteen PIDs can be specified.

       -g#     Traces given groups only.  Up to sixteen Group IDs can be specified.

       -p#     Traces given PIDs only.	Up to sixteen PIDs can be specified.

       -s#     Traces given system calls only.	Up to sixteen PIDs can be specified.

       -u#     Traces given UIDs only.	Up to sixteen PIDs can be specified.

       trace -f ls.dump ls -l /dev >ls.out
       runs the cmd ls -l /dev and puts the trace in ls.dump and output in ls.out.
       trace -f csh.trace -p $$ &
       will trace your login shell in the background. To stop the trace just send it a termination signal (that is, kill -TERM trace_pid).

       Due to security, no one, not even the super-user can trace anyone else's programs. This sort of negates some of the usefulness  of  the	-g
       and -u flags.

       The program cannot be traced.

       Only 16 numbers can be given to the -c, -p, -g, -u, and -s flags.

       The kernel configuration file must contain the following:
       options	       SYS_TRACE
       pseudo-device   sys_trace

       In addition, the superuser must use the following command sequence to create the device:
       cd /dev
       MAKEDEV trace
       If both lines are not in the configuration file or if the device is not made, the message "Cannot open /dev/trace" appears.

       /dev/trace     read only character special device for reading syscall data.

       trace.dump     default file for the system call trace data.

See Also
       open(2), close(2), ioctl(2), select(2), read(2), trace(5)


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