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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)ktrace.1 8.1 (Berkeley) 6/6/93 33.\" $FreeBSD$ 34.\" 35.Dd February 23, 2008 36.Dt KTRACE 1 37.Os 38.Sh NAME 39.Nm ktrace 40.Nd enable kernel process tracing 41.Sh SYNOPSIS 42.Nm 43.Op Fl aCcdi 44.Op Fl f Ar trfile 45.Op Fl g Ar pgrp | Fl p Ar pid 46.Op Fl t Ar trstr 47.Nm 48.Op Fl adi 49.Op Fl f Ar trfile 50.Op Fl t Ar trstr 51.Ar command 52.Sh DESCRIPTION 53The 54.Nm 55utility enables kernel trace logging for the specified processes. 56Kernel trace data is logged to the file 57.Pa ktrace.out . 58The kernel operations that are traced include system calls, namei 59translations, signal processing, and 60.Tn I/O . 61.Pp 62Once tracing is enabled on a process, trace data will be logged until 63either the process exits or the trace point is cleared. 64A traced process can generate enormous amounts of log data quickly; 65It is strongly suggested that users memorize how to disable tracing before 66attempting to trace a process. 67The following command is sufficient to disable tracing on all user-owned 68processes, and, if executed by root, all processes: 69.Pp 70.Dl \&$ ktrace -C 71.Pp 72The trace file is not human readable; use 73.Xr kdump 1 74to decode it. 75.Pp 76The utility may be used only with a kernel that has been built with the 77.Dq KTRACE 78option in the kernel configuration file. 79.Pp 80The options are: 81.Bl -tag -width indent 82.It Fl a 83Append to the trace file instead of recreating it. 84.It Fl C 85Disable tracing on all user-owned processes, and, if executed by root, all 86processes in the system. 87.It Fl c 88Clear the trace points associated with the specified file or processes. 89.It Fl d 90Descendants; perform the operation for all current children of the 91designated processes. 92.It Fl f Ar trfile 93Log trace records to 94.Ar trfile 95instead of 96.Pa ktrace.out . 97.It Fl g Ar pgid 98Enable (disable) tracing on all processes in the process group (only one 99.Fl g 100flag is permitted). 101.It Fl i 102Inherit; pass the trace flags to all future children of the designated 103processes. 104.It Fl p Ar pid 105Enable (disable) tracing on the indicated process id (only one 106.Fl p 107flag is permitted). 108.It Fl t Ar trstr 109The string argument represents the kernel trace points, one per letter. 110The following table equates the letters with the tracepoints: 111.Pp 112.Bl -tag -width flag -compact 113.It Cm c 114trace system calls 115.It Cm n 116trace namei translations 117.It Cm i 118trace 119.Tn I/O 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 + 129trace the default set of trace points - 130.Cm c , n , i , s , t , u 131.El 132.It Ar command 133Execute 134.Ar command 135with the specified trace flags. 136.El 137.Pp 138The 139.Fl p , 140.Fl g , 141and 142.Ar command 143options are mutually exclusive. 144.Sh EXAMPLES 145# trace all kernel operations of process id 34 146.Dl $ ktrace -p 34 147.Pp 148# trace all kernel operations of processes in process group 15 and 149# pass the trace flags to all current and future children 150.Dl $ ktrace -idg 15 151.Pp 152# disable all tracing of process 65 153.Dl $ ktrace -cp 65 154.Pp 155# disable tracing signals on process 70 and all current children 156.Dl $ ktrace -t s -cdp 70 157.Pp 158# enable tracing of 159.Tn I/O 160on process 67 161.Dl $ ktrace -ti -p 67 162.Pp 163# run the command "w", tracing only system calls 164.Dl $ ktrace -tc w 165.Pp 166# disable all tracing to the file "tracedata" 167.Dl $ ktrace -c -f tracedata 168.Pp 169# disable tracing of all user-owned processes 170.Dl $ ktrace -C 171.Sh SEE ALSO 172.Xr kdump 1 173.Sh HISTORY 174The 175.Nm 176command appeared in 177.Bx 4.4 . 178.Sh BUGS 179Only works if 180.Ar trfile 181is a regular file. 182