KTRACE(1)                  OpenBSD Reference 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
     ktrace 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 ei-
     ther the process exits or the trace point is cleared.  A traced process
     can generate enormous amounts of log data quickly; It is strongly sug-
     gested 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 pro-
             cesses.

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

     -f file
             Log trace records to file 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 des-
             ignated 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 trace-
             points:

             c     trace system calls
             e     trace emulation changes
             n     trace namei translations
             i     trace I/O
             s     trace signal processing

     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.

OpenBSD 2.6                      June 6, 1993                                2
