path: root/usr.bin/ktrace/ktrace.1

.\"	$OpenBSD: ktrace.1,v 1.29 2016/07/18 09:36:50 guenther 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.
.\"
.\"	from: @(#)ktrace.1	8.1 (Berkeley) 6/6/93
.\"
.Dd $Mdocdate: July 18 2016 $
.Dt KTRACE 1
.Os
.Sh NAME
.Nm ktrace
.Nd enable kernel process tracing
.Sh SYNOPSIS
.Nm ktrace
.Op Fl aBCcdi
.Op Fl f Ar trfile
.Op Fl g Ar pgid
.Op Fl p Ar pid
.Op Fl t Ar trstr
.Nm ktrace
.Op Fl adi
.Op Fl f Ar trfile
.Op Fl t Ar trstr
.Ar command
.Sh DESCRIPTION
.Nm ktrace
enables kernel trace logging for the specified processes.
By default, kernel trace data is logged to the file
.Pa ktrace.out ,
unless overridden by the
.Fl f
option.
The kernel operations traced are system calls, namei translations,
signal processing and 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
The options are as follows:
.Bl -tag -width 9n
.It Fl a
Append to the trace file instead of recreating it.
.It Fl B
Set the
.Ev LD_BIND_NOW
environment variable to specify that the dynamic linker should process
relocations immediately instead of as they are encountered.
This eliminates the resulting
.Xr ld.so 1
relocation sequences.
.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 trace file or any specified
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 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 p Ar pid
Enable (disable) tracing on the indicated process ID (only one
.Fl p
flag is permitted).
.It Fl t Ar trstr
The string argument represents the kernel trace points, one per letter.
By default all trace points except for
.Cm X
are enabled.
The following table equates the letters with the trace points:
.Pp
.Bl -tag -width flag -offset indent -compact
.It Cm c
trace system calls
.It Cm i
trace I/O
.It Cm n
trace namei translations
.It Cm p
trace violation of
.Xr pledge 2
restrictions
.It Cm s
trace signal processing
.It Cm t
trace various structures
.It Cm u
trace user data coming from
.Xr utrace 2
.It Cm x
trace argument vector in
.Xr execve 2
.It Cm X
trace environment in
.Xr execve 2
.It Cm +
trace the default points
.El
.It Ar command
Execute
.Ar command
with the specified trace flags.
.El
.Pp
The
.Fl p ,
.Fl g ,
and
.Ar command
options are mutually exclusive.
.Sh FILES
.Bl -tag -width ktrace.out -compact
.It Pa ktrace.out
default ktrace dump file
.El
.Sh EXAMPLES
Trace all kernel operations of process ID 34:
.Dl $ ktrace -p 34
.Pp
Trace all kernel operations of processes in process group 15 and
pass the trace flags to all current and future children:
.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 I/O on process 67:
.Dl $ ktrace -ti -p 67
.Pp
Run the command
.Xr w 1 ,
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
.Sh SEE ALSO
.Xr kdump 1 ,
.Xr ktrace 2 ,
.Xr utrace 2
.Sh HISTORY
The
.Nm ktrace
command appeared in
.Bx 4.4 .