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.\" 3. 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 July 24, 2017 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. 88See also the 89.Fl i 90option. 91.It Fl f Ar trfile 92Log trace records to 93.Ar trfile 94instead of 95.Pa ktrace.out . 96.It Fl g Ar pgid 97Enable (disable) tracing on all processes in the process group (only one 98.Fl g 99flag is permitted). 100.It Fl i 101Inherit; pass the trace flags to all future children of the designated 102processes. 103See also the 104.Fl d 105option. 106.It Fl p Ar pid 107Enable (disable) tracing on the indicated process id (only one 108.Fl p 109flag is permitted). 110.It Fl t Ar trstr 111Specify the list of trace points to enable or disable, one per letter. 112If an explicit list is not specified, the default set of trace points is used. 113.Pp 114The following trace points are supported: 115.Pp 116.Bl -tag -width flag -compact 117.It Cm c 118trace system calls 119.It Cm f 120trace page faults 121.It Cm i 122trace 123.Tn I/O 124.It Cm n 125trace namei translations 126.It Cm p 127trace capability check failures 128.It Cm s 129trace signal processing 130.It Cm t 131trace various structures 132.It Cm u 133userland traces 134.It Cm w 135context switches 136.It Cm y 137trace 138.Xr sysctl 3 139requests 140.It Cm + 141trace the default set of trace points - 142.Cm c , i , n , p , s , t , u , y 143.El 144.It Ar command 145Execute 146.Ar command 147with the specified trace flags. 148.El 149.Pp 150The 151.Fl p , 152.Fl g , 153and 154.Ar command 155options are mutually exclusive. 156.Sh EXAMPLES 157Run "make", then trace it and any child processes: 158.Dl $ ktrace -i make 159.Pp 160Trace all kernel operations of process id 34: 161.Dl $ ktrace -p 34 162.Pp 163Trace all kernel operations of processes in process group 15 and 164pass the trace flags to all current and future children: 165.Dl $ ktrace -idg 15 166.Pp 167Disable all tracing of process 65: 168.Dl $ ktrace -cp 65 169.Pp 170Disable tracing signals on process 70 and all current children: 171.Dl $ ktrace -t s -cdp 70 172.Pp 173Enable tracing of 174.Tn I/O 175on process 67: 176.Dl $ ktrace -ti -p 67 177.Pp 178Disable all tracing to the file "tracedata": 179.Dl $ ktrace -c -f tracedata 180.Pp 181Disable tracing of all user-owned processes: 182.Dl $ ktrace -C 183.Sh SEE ALSO 184.Xr dtrace 1 , 185.Xr kdump 1 , 186.Xr truss 1 , 187.Xr ktrace 2 188.Sh HISTORY 189The 190.Nm 191command appeared in 192.Bx 4.4 . 193.Sh BUGS 194Only works if 195.Ar trfile 196is a regular file. 197