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.\" @(#)core.5 8.3 (Berkeley) 12/11/93 33.\" $FreeBSD: src/share/man/man5/core.5,v 1.8.2.5 2003/01/07 22:03:50 keramida Exp $ 34.\" $DragonFly: src/share/man/man5/core.5,v 1.3 2004/03/11 12:28:56 hmp Exp $ 35.\" 36.Dd January 9, 2002 37.Dt CORE 5 38.Os 39.Sh NAME 40.Nm core 41.Nd memory image file format 42.Sh SYNOPSIS 43.In sys/param.h 44.Sh DESCRIPTION 45A small number of signals which cause abnormal termination of a process 46also cause a record of the process's in-core state to be written 47to disk for later examination by one of the available debuggers. 48(See 49.Xr sigaction 2 . ) 50This memory image is written to a file named by default 51.Nm programname.core 52in the working directory; 53provided the terminated process had write permission in the directory, 54and provided the abnormality did not cause 55a system crash. 56(In this event, the decision to save the core file is arbitrary, see 57.Xr savecore 8 . ) 58.Pp 59The maximum size of a core file is limited by 60.Xr setrlimit 2 . 61Files which would be larger than the limit are not created. 62.Pp 63The name of the file is controlled via the 64.Xr sysctl 8 65variable 66.Va kern.corefile . 67The contents of this variable describes a filename to store 68the core image to. 69This filename can be absolute, or relative (which 70will resolve to the current working directory of the program 71generating it). 72Any sequence of 73.Em \&%N 74in this filename template will be replaced by the process name, 75.Em \&%P 76by the processes PID, and 77.Em \&%U 78by the UID. 79The name defaults to 80.Em \&%N.core , 81yielding the traditional 82.Dx 83behaviour. 84.Pp 85By default, a process that changes user or group credentials whether 86real or effective will not create a corefile. 87This behaviour can be 88changed to generate a core dump by setting the 89.Xr sysctl 8 90variable 91.Va kern.sugid_coredump 92to 1. 93.Pp 94The core file consists of the 95.Fa u. 96area, whose size (in pages) is 97defined by the 98.Dv UPAGES 99manifest in the 100.Aq Pa sys/param.h 101file. 102The 103.Fa u. 104area starts with a 105.Fa user 106structure as given in 107.Aq Pa sys/user.h . 108The remainder of the core 109file consists of the data pages followed by 110the stack pages of the process image. 111The amount of data space image in the core 112file is given (in pages) by the 113variable 114.Fa u_dsize 115in the 116.Fa u. 117area. 118The amount of stack image in the core file is given (in pages) by the 119variable 120.Fa u_ssize 121in the 122.Fa u. 123area. 124The size of a ``page'' is given by the constant 125.Dv PAGE_SIZE 126(also from 127.Aq Pa sys/param.h ) . 128.Sh EXAMPLES 129In order to store all core images in per-user private areas under 130.Pa /var/coredumps , 131the following 132.Xr sysctl 8 133command can be used: 134.Pp 135.Dl sysctl kern.corefile="/var/coredumps/\&%U/\&%N.core" 136.Sh SEE ALSO 137.Xr gdb 1 , 138.Xr kgdb 1 , 139.Xr setrlimit 2 , 140.Xr sigaction 2 , 141.Xr sysctl 8 142.Sh HISTORY 143A 144.Nm 145file format appeared in 146.At v6 . 147