1.\" Copyright (c) 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)ktrace.1 8.1 (Berkeley) 6/6/93 29.\" $FreeBSD$ 30.\" 31.Dd March 31, 2016 32.Dt KTRACE 1 33.Os 34.Sh NAME 35.Nm ktrace 36.Nd enable kernel process tracing 37.Sh SYNOPSIS 38.Nm 39.Op Fl aCcdi 40.Op Fl f Ar trfile 41.Op Fl g Ar pgrp | Fl p Ar pid 42.Op Fl t Ar trstr 43.Nm 44.Op Fl adi 45.Op Fl f Ar trfile 46.Op Fl t Ar trstr 47.Ar command 48.Sh DESCRIPTION 49The 50.Nm 51utility enables kernel trace logging for the specified processes. 52Kernel trace data is logged to the file 53.Pa ktrace.out . 54The kernel operations that are traced include system calls, namei 55translations, signal processing, and 56.Tn I/O . 57.Pp 58Once tracing is enabled on a process, trace data will be logged until 59either the process exits or the trace point is cleared. 60A traced process can generate enormous amounts of log data quickly; 61It is strongly suggested that users memorize how to disable tracing before 62attempting to trace a process. 63The following command is sufficient to disable tracing on all user-owned 64processes, and, if executed by root, all processes: 65.Pp 66.Dl \&$ ktrace -C 67.Pp 68The trace file is not human readable; use 69.Xr kdump 1 70to decode it. 71.Pp 72The utility may be used only with a kernel that has been built with the 73.Dq KTRACE 74option in the kernel configuration file. 75.Pp 76The options are: 77.Bl -tag -width indent 78.It Fl a 79Append to the trace file instead of recreating it. 80.It Fl C 81Disable tracing on all user-owned processes, and, if executed by root, all 82processes in the system. 83.It Fl c 84Clear the specified trace points associated with the given file or processes. 85.It Fl d 86Descendants; perform the operation for all current children of the 87designated processes. 88.It Fl f Ar trfile 89Log trace records to 90.Ar trfile 91instead of 92.Pa ktrace.out . 93.It Fl g Ar pgid 94Enable (disable) tracing on all processes in the process group (only one 95.Fl g 96flag is permitted). 97.It Fl i 98Inherit; pass the trace flags to all future children of the designated 99processes. 100.It Fl p Ar pid 101Enable (disable) tracing on the indicated process id (only one 102.Fl p 103flag is permitted). 104.It Fl t Ar trstr 105Specify the list of trace points to enable or disable, one per letter. 106If an explicit list is not specified, the default set of trace points is used. 107.Pp 108The following trace points are supported: 109.Pp 110.Bl -tag -width flag -compact 111.It Cm c 112trace system calls 113.It Cm f 114trace page faults 115.It Cm i 116trace 117.Tn I/O 118.It Cm n 119trace namei translations 120.It Cm p 121trace capability check failures 122.It Cm s 123trace signal processing 124.It Cm t 125trace various structures 126.It Cm u 127userland traces 128.It Cm w 129context switches 130.It Cm y 131trace 132.Xr sysctl 3 133requests 134.It Cm + 135trace the default set of trace points - 136.Cm c , i , n , p , s , t , u , y 137.El 138.It Ar command 139Execute 140.Ar command 141with the specified trace flags. 142.El 143.Pp 144The 145.Fl p , 146.Fl g , 147and 148.Ar command 149options are mutually exclusive. 150.Sh EXAMPLES 151# trace all kernel operations of process id 34 152.Dl $ ktrace -p 34 153.Pp 154# trace all kernel operations of processes in process group 15 and 155# pass the trace flags to all current and future children 156.Dl $ ktrace -idg 15 157.Pp 158# disable all tracing of process 65 159.Dl $ ktrace -cp 65 160.Pp 161# disable tracing signals on process 70 and all current children 162.Dl $ ktrace -t s -cdp 70 163.Pp 164# enable tracing of 165.Tn I/O 166on process 67 167.Dl $ ktrace -ti -p 67 168.Pp 169# run the command "w", tracing only system calls 170.Dl $ ktrace -tc w 171.Pp 172# disable all tracing to the file "tracedata" 173.Dl $ ktrace -c -f tracedata 174.Pp 175# disable tracing of all user-owned processes 176.Dl $ ktrace -C 177.Sh SEE ALSO 178.Xr kdump 1 , 179.Xr ktrace 2 180.Sh HISTORY 181The 182.Nm 183command appeared in 184.Bx 4.4 . 185.Sh BUGS 186Only works if 187.Ar trfile 188is a regular file. 189