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KTRACE(1)		     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  command  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 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  desig-
	     nated 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
	     n	   trace namei translations
	     i	   trace I/O
	     s	   trace signal processing
	     u	   userland traces
	     w	   context switches

     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)

BUGS
     Only works if file is a regular file.

HISTORY
     The ktrace command appeared in 4.4BSD.

Darwin 8.0.1			  June 6, 1993			       KTRACE(1)
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