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.Dd August 26, 2019 29.Dt KTRACE 1 30.Os 31.Sh NAME 32.Nm ktrace 33.Nd enable kernel process tracing 34.Sh SYNOPSIS 35.Nm 36.Op Fl aCcdi 37.Op Fl f Ar trfile 38.Op Fl g Ar pgrp | Fl p Ar pid 39.Op Fl t Ar trstr 40.Nm 41.Op Fl adi 42.Op Fl f Ar trfile 43.Op Fl t Ar trstr 44.Ar command 45.Sh DESCRIPTION 46The 47.Nm 48utility enables kernel trace logging for the specified processes. 49Kernel trace data is logged to the file 50.Pa ktrace.out . 51The kernel operations that are traced include system calls, namei 52translations, signal processing, and 53.Tn I/O . 54.Pp 55Once tracing is enabled on a process, trace data will be logged until 56either the process exits or the trace point is cleared. 57A traced process can generate enormous amounts of log data quickly; 58It is strongly suggested that users memorize how to disable tracing before 59attempting to trace a process. 60The following command is sufficient to disable tracing on all user-owned 61processes, and, if executed by root, all processes: 62.Pp 63.Dl \&$ ktrace -C 64.Pp 65The trace file is not human readable; use 66.Xr kdump 1 67to decode it. 68.Pp 69The utility may be used only with a kernel that has been built with the 70.Dq KTRACE 71option in the kernel configuration file. 72.Pp 73The options are: 74.Bl -tag -width indent 75.It Fl a 76Append to the trace file instead of recreating it. 77.It Fl C 78Disable tracing on all user-owned processes, and, if executed by root, all 79processes in the system. 80.It Fl c 81Clear the specified trace points associated with the given file or processes. 82.It Fl d 83Descendants; perform the operation for all current children of the 84designated processes. 85See also the 86.Fl i 87option. 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. 100See also the 101.Fl d 102option. 103.It Fl p Ar pid 104Enable (disable) tracing on the indicated process id (only one 105.Fl p 106flag is permitted). 107.It Fl t Ar trstr 108Specify the list of trace points to enable or disable, one per letter. 109If an explicit list is not specified, the default set of trace points is used. 110.Pp 111The following trace points are supported: 112.Pp 113.Bl -tag -width flag -compact 114.It Cm c 115trace system calls 116.It Cm f 117trace page faults 118.It Cm i 119trace 120.Tn I/O 121.It Cm n 122trace namei translations 123.It Cm p 124trace capability check failures 125.It Cm s 126trace signal processing 127.It Cm t 128trace various structures 129.It Cm u 130userland traces generated by 131.Xr utrace 2 132.It Cm w 133context switches 134.It Cm y 135trace 136.Xr sysctl 3 137requests 138.It Cm + 139trace the default set of trace points - 140.Cm c , i , n , p , s , t , u , y 141.El 142.It Ar command 143Execute 144.Ar command 145with the specified trace flags. 146.El 147.Pp 148The 149.Fl p , 150.Fl g , 151and 152.Ar command 153options are mutually exclusive. 154.Sh EXAMPLES 155Run "make", then trace it and any child processes: 156.Dl $ ktrace -i make 157.Pp 158Trace all kernel operations of process id 34: 159.Dl $ ktrace -p 34 160.Pp 161Trace all kernel operations of processes in process group 15 and 162pass the trace flags to all current and future children: 163.Dl $ ktrace -idg 15 164.Pp 165Disable all tracing of process 65: 166.Dl $ ktrace -cp 65 167.Pp 168Disable tracing signals on process 70 and all current children: 169.Dl $ ktrace -t s -cdp 70 170.Pp 171Enable tracing of 172.Tn I/O 173on process 67: 174.Dl $ ktrace -ti -p 67 175.Pp 176Disable all tracing to the file "tracedata": 177.Dl $ ktrace -c -f tracedata 178.Pp 179Disable tracing of all user-owned processes: 180.Dl $ ktrace -C 181.Sh SEE ALSO 182.Xr dtrace 1 , 183.Xr kdump 1 , 184.Xr truss 1 , 185.Xr ktrace 2 , 186.Xr utrace 2 187.Sh HISTORY 188The 189.Nm 190command appeared in 191.Bx 4.4 . 192.Sh BUGS 193Only works if 194.Ar trfile 195is a regular file. 196