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 May 31, 2012 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 trace points associated with the specified 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 105The string argument represents the kernel trace points, one per letter. 106The following table equates the letters with the tracepoints: 107.Pp 108.Bl -tag -width flag -compact 109.It Cm c 110trace system calls 111.It Cm f 112trace page faults 113.It Cm i 114trace 115.Tn I/O 116.It Cm n 117trace namei translations 118.It Cm p 119trace capability check failures 120.It Cm s 121trace signal processing 122.It Cm t 123trace various structures 124.It Cm u 125userland traces 126.It Cm w 127context switches 128.It Cm y 129trace 130.Xr sysctl 3 131requests 132.It Cm + 133trace the default set of trace points - 134.Cm c , i , n , p , s , t , u , y 135.El 136.It Ar command 137Execute 138.Ar command 139with the specified trace flags. 140.El 141.Pp 142The 143.Fl p , 144.Fl g , 145and 146.Ar command 147options are mutually exclusive. 148.Sh EXAMPLES 149# trace all kernel operations of process id 34 150.Dl $ ktrace -p 34 151.Pp 152# trace all kernel operations of processes in process group 15 and 153# pass the trace flags to all current and future children 154.Dl $ ktrace -idg 15 155.Pp 156# disable all tracing of process 65 157.Dl $ ktrace -cp 65 158.Pp 159# disable tracing signals on process 70 and all current children 160.Dl $ ktrace -t s -cdp 70 161.Pp 162# enable tracing of 163.Tn I/O 164on process 67 165.Dl $ ktrace -ti -p 67 166.Pp 167# run the command "w", tracing only system calls 168.Dl $ ktrace -tc w 169.Pp 170# disable all tracing to the file "tracedata" 171.Dl $ ktrace -c -f tracedata 172.Pp 173# disable tracing of all user-owned processes 174.Dl $ ktrace -C 175.Sh SEE ALSO 176.Xr kdump 1 177.Sh HISTORY 178The 179.Nm 180command appeared in 181.Bx 4.4 . 182.Sh BUGS 183Only works if 184.Ar trfile 185is a regular file. 186