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KTRACE(1)               FreeBSD General Commands Manual              KTRACE(1)

NAME
     ktrace - enable kernel process tracing

SYNOPSIS
     ktrace [-aCcdi] [-f trfile] [-g pgrp | -p pid] [-t trstr]
     ktrace [-adi] [-f trfile] [-t trstr] command

DESCRIPTION
     The ktrace utility enables kernel trace logging for the specified
     processes.  Kernel trace data is logged to the file ktrace.out.  The
     kernel operations that are traced include system calls, namei
     translations, signal processing, and I/O.

     Once tracing is enabled on a process, trace data will be logged until
     either the process exits or the trace point is cleared.  A traced process
     can generate enormous amounts of log data quickly; It is strongly
     suggested that users memorize how to disable tracing before attempting to
     trace a process.  The following command is sufficient to disable tracing
     on all user owned processes, and, if executed by root, all processes:

           $ ktrace -C

     The trace file is not human readable; use kdump(1) to decode it.

     The options are as follows:

     -a      Append to the trace file instead of recreating it.

     -C      Disable tracing on all user owned processes, and, if executed by
             root, all processes in the system.

     -c      Clear the trace points associated with the specified file or
             processes.

     -d      Descendants; perform the operation for all current children of
             the designated processes.

     -f trfile
             Log trace records to trfile instead of ktrace.out.

     -g pgid
             Enable (disable) tracing on all processes in the process group
             (only one -g flag is permitted).

     -i      Inherit; pass the trace flags to all future children of the
             designated processes.

     -p pid  Enable (disable) tracing on the indicated process id (only one -p
             flag is permitted).

     -t trstr
             The string argument represents the kernel trace points, one per
             letter.  The following table equates the letters with the
             tracepoints:

             c     trace system calls
             n     trace namei translations
             i     trace I/O
             s     trace signal processing
             u     userland traces
             w     context switches
             +     trace the default set of trace points - c, n, i, s, u

     command
             Execute command with the specified trace flags.

     The -p, -g, and command options are mutually exclusive.

EXAMPLES
     # trace all kernel operations of process id 34
           $ ktrace -p 34

     # trace all kernel operations of processes in process group 15 and # pass
     the trace flags to all current and future children
           $ ktrace -idg 15

     # disable all tracing of process 65
           $ ktrace -cp 65

     # disable tracing signals on process 70 and all current children
           $ ktrace -t s -cdp 70

     # enable tracing of I/O on process 67
           $ ktrace -ti -p 67

     # run the command "w", tracing only system calls
           $ ktrace -tc w

     # disable all tracing to the file "tracedata"
           $ ktrace -c -f tracedata

     # disable tracing of all processes owned by the user
           $ ktrace -C

SEE ALSO
     kdump(1)

HISTORY
     The ktrace command appeared in 4.4BSD.

BUGS
     Only works if trfile is a regular file.

FreeBSD 11.0-PRERELEASE          June 6, 1993          FreeBSD 11.0-PRERELEASE

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | HISTORY | BUGS

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