NAME    [Toc]    [Back]

     ktrace - enable kernel process tracing

SYNOPSIS    [Toc]    [Back]

     ktrace [-aCcdi] [-f trfile] [-g pgid] [-p pid] [-t trstr]
     ktrace [-adi] [-f trfile] [-t trstr] command

DESCRIPTION    [Toc]    [Back]

     ktrace enables kernel trace logging for the  specified  processes.  By default,
  kernel  trace data is logged to the file ktrace.out,
unless overridden
 by the -f option.  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 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
               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 default flags are c, e, i, n, and s.
The following
 table equates  the  letters  with  the  tracepoints:

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

     command   Execute command with the specified trace flags.

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

FILES    [Toc]    [Back]

     ktrace.out  default ktrace dump file

EXAMPLES    [Toc]    [Back]

     # 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    [Toc]    [Back]

     kdump(1)

HISTORY    [Toc]    [Back]

     The ktrace command appeared in 4.4BSD.

OpenBSD      3.6                           June      6,      1993