.\"	$NetBSD: ktrace.1,v 1.39 2007/08/27 16:35:47 dsl Exp $
.\"
.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)ktrace.1	8.1 (Berkeley) 6/6/93
.\"
.Dd August 27, 2007
.Dt KTRACE 1
.Os
.Sh NAME
.Nm ktrace , ktruss
.Nd enable kernel process tracing
.Sh SYNOPSIS
.Nm
.Op Fl aCcdins
.Op Fl f Ar trfile
.Op Fl g Ar pgrp
.Op Fl p Ar pid
.Op Fl t Ar trstr
.Nm
.Op Fl adis
.Op Fl f Ar trfile
.Op Fl t Ar trstr
.Ar command
.Nm ktruss
.Op Fl aCcdilnRT
.Op Fl e Ar emulation
.Op Fl f Ar infile
.Op Fl g Ar pgrp
.Op Fl m Ar maxdata
.Op Fl o Ar outfile
.Op Fl p Ar pid
.Op Fl t Ar trstr
.Nm ktruss
.Op Fl adinRT
.Op Fl e Ar emulation
.Op Fl m Ar maxdata
.Op Fl o Ar outfile
.Op Fl t Ar trstr
.Op Fl v Ar vers
command
.Sh DESCRIPTION
.Nm
enables kernel trace logging for the specified processes.
Kernel trace data is logged to the file
.Pa ktrace.out .
The kernel operations that are traced include system calls, namei
translations, signal processing, and
.Tn I/O .
.Pp
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:
.Pp
.Dl \&$ ktrace -C
.Pp
The trace file is not human readable; use
.Xr kdump 1
to decode it.
.Pp
.Nm ktruss
is functionally the same as
.Nm ktrace
except that trace output is printed
on standard output or to the file specified with the
.Fl o
option.
.Nm ktruss
is useful to see the kernel operations interleaved with
the program output.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl a
Append to the trace file instead of truncating it.
.It Fl C
Disable tracing on all user owned processes, and, if executed by root, all
processes in the system.
.It Fl c
Clear the trace points associated with the specified file or processes.
.It Fl d
Descendants; perform the operation for all current children of the
designated processes.
.It Fl f Ar trfile
Log trace records to
.Ar trfile
instead of
.Pa ktrace.out .
.It Fl f Ar infile
Read the trace records from
.Ar infile
and print them in a human readable format to standard out.
.It Fl g Ar pgid
Enable (disable) tracing on all processes in the process group (only one
.Fl g
flag is permitted).
.It Fl i
Inherit; pass the trace flags to all future children of the designated
processes.
.It Fl l
Poll the trace file for new data and print it to standard out.
Only for use together with the
.Fl f
option.
.It Fl m Ar maxdata
Print at most
.Ar maxdata
bytes of data.
This is used for pointer type arguments, e.g., strings.
The data will be escaped in C-style unless
.Fl x
is specified when it will be output in hex and ascii.
.It Fl n
Stop tracing if attempts to write to the trace file would block.
This option always affects
.Nm ktruss
and only affects
.Nm ktrace
when writing to
.Dv stdout .
If this flag is not set, then the traced program will block until it can
write more data to the trace file descriptor.
.It Fl o Ar outfile
Log trace records to
.Ar outfile .
Without this option
.Nm ktruss
will print its output in a human
readable format to standard out.
.It Fl p Ar pid
Enable (disable) tracing on the indicated process id (only one
.Fl p
flag is permitted).
.It Fl s
Write to the trace file with synchronized I/O.
.It Fl R
Display relative time stamps to output.
.It Fl T
Same as the
.Fl R
option, but use absolute timestamps instead.
.It Fl t Ar trstr
The string argument represents the kernel trace points, one per letter.
The following table equates the letters with the tracepoints:
.Pp
.Bl -tag -width flag -compact
.It Cm A
trace all tracepoints
.It Cm a
trace exec arguments
.It Cm c
trace system calls
.It Cm e
trace emulation changes
.It Cm i
trace
.Tn I/O
.It Cm l
trace Mach out of line data when running Mach binaries with COMPAT_MACH
(currently limited to i386 and powerpc ports).
.It Cm m
trace Mach messages when running Mach binaries with COMPAT_MACH
(currently limited to i386 and powerpc ports).
.It Cm n
trace namei translations
.It Cm S
trace MIB access (sysctl)
.It Cm s
trace signal processing
.\" .It Cm U
.\" trace scheduler activations upcall data
.It Cm u
trace user data
.It Cm v
trace exec environment
.It Cm w
trace context switches
.It Cm +
trace the default set of trace points (c, e, i, l, m, n, s, u)
.It Cm -
do not trace following trace points
.El
.It Fl e Ar emulation
If an emulation of a process is unknown,
interpret system call maps assuming the named emulation instead of
default "netbsd".
.It Ar command
Execute
.Ar command
with the specified trace flags.
.It Fl v Ar version
Determines the
.Ar version
of the file generated.
Version 0 is the compatible ktrace format, and
version 1 is the new format with lwp IDs and nanosecond (instead of
microsecond) timestamps.
.El
.Pp
The
.Fl p ,
.Fl g ,
and
.Ar command
options are mutually exclusive.
The
.Fl R
and
.Fl T
options are also mutually exclusive.
.Sh EXAMPLES
# trace all kernel operations of process id 34
.Dl $ ktrace -p 34
.Pp
.Bd -literal
# trace all kernel operations of processes in process group 15 and
# pass the trace flags to all current and future children
.Ed
.Dl $ ktrace -idg 15
.Pp
# disable all tracing of process 65
.Dl $ ktrace -cp 65
.Pp
# disable tracing signals on process 70 and all current children
.Dl $ ktrace -t s -cdp 70
.Pp
# enable tracing of
.Tn I/O
on process 67
.Dl $ ktrace -ti -p 67
.Pp
# run the command "w", tracing only system calls
.Dl $ ktrace -tc w
.Pp
# disable all tracing to the file "tracedata"
.Dl $ ktrace -c -f tracedata
.Pp
# disable tracing of all processes owned by the user
.Dl $ ktrace -C
.Pp
# run the command "w", displaying to standard output
.Dl $ ktruss w
.Pp
# trace process 42 and log the records to "ktruss.out"
.Dl $ ktruss -p 42 -o ktruss.out
.Pp
# poll ktruss.out for available records and print them
.Dl $ ktruss -lf ktruss.out
.Sh SEE ALSO
.Xr kdump 1 ,
.Xr ktrace 2
.Sh HISTORY
The
.Nm
command appears in
.Bx 4.4 .