The
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 utility may be used only with a kernel that has been built with the
``KTRACE''
option in the kernel configuration file.
The options are:
-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 cnistuw
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
t
trace various structures
u
userland traces
w
context switches
+
trace the default set of trace points -
c , n , i , s , t , 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
