KTRACE(1) OpenBSD Reference Manual KTRACE(1)NAMEktrace - enable kernel process tracing
SYNOPSISktrace [-aCcdi] [-f trfile] [-g pgid] [-p pid] [-t trstr]
ktrace [-adi] [-f trfile] [-t trstr] command
DESCRIPTIONktrace 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 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 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
ktrace.out default ktrace dump file
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(1), 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 ALSOkdump(1), ktrace(2)HISTORY
The ktrace command appeared in 4.4BSD.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9
