1.\" Copyright (c) 1980, 1991, 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.\" From: @(#)swapon.8 8.1 (Berkeley) 6/5/93 33.\" $Id$ 34.\" 35.Dd May 12, 1995 36.Dt DUMPON 8 37.Os FreeBSD 2.1 38.Sh NAME 39.Nm dumpon 40.Nd "specify a device for crash dumps" 41.Sh SYNOPSIS 42.Nm dumpon 43.Op Fl v 44.Ar special_file 45.Sh DESCRIPTION 46.Nm Dumpon 47is used to specify a device where the kernel can save a crash dump in 48the case of a panic. 49The system begins with no dump area configured for safety, unless a 50.Dq dumps on 51clause was specified in the input to 52.Xr config 8 . 53The dump device must be one of the swap areas 54specified in the configuration file, and it must be at least the size 55of physical memory. 56Calls to 57.Nm dumpon 58normally occur in the system multi-user initialization file 59.Pa /etc/rc , 60before the 61.Xr savecore 8 62program is run. 63The 64.Fl v 65flag can be specified to cause the 66.Nm 67program to be verbose about its activity. 68.Pp 69The 70.Nm 71program operates by setting the 72.Xr sysctl 3 73MIB variable 74.Dq kern.dumpdev 75to the device number of the designated 76.Ar special_file 77or to 78.Dv NODEV 79(meaning that no dumps are to be taken) if 80.Ar special_file 81is the text string 82.Dq Li off . 83.Sh SEE ALSO 84.Xr dumpon 2 , 85.Xr init 8 , 86.Xr rc 8 , 87.Xr savecore 8 88.Sh FILES 89.Bl -tag -width /dev/[ws]d?b -compact 90.It Pa /dev/[ws]d?b 91standard paging devices 92.El 93.Sh BUGS 94Because the filesystem layer is already dead by the time a crash dump 95is taken, it is not possible to send crash dumps directly to a file. 96.Sh HISTORY 97The 98.Nm 99command appeared in 100.Tn FreeBSD 1012.1. 102