freebsd-skq/usr.bin/gcore/gcore.1

.\" Copyright (c) 1983, 1990, 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)gcore.1	8.2 (Berkeley) 4/18/94
.\" $FreeBSD$
.\"
.Dd April 24, 2021
.Dt GCORE 1
.Os
.Sh NAME
.Nm gcore
.Nd get core images of running process
.Sh SYNOPSIS
.Nm
.Op Fl f
.Op Fl k
.Op Fl c Ar core
.Op Ar executable
.Ar pid
.Sh DESCRIPTION
The
.Nm
utility creates a core image of the specified process,
suitable for use with
.Xr gdb 1 .
By default, the core is written to the file
.Dq Pa core.<pid> .
The process identifier,
.Ar pid ,
must be given on the command line.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl c
Write the core file to the specified file instead of
.Dq Pa core.<pid> .
.It Fl f
Dumps all available segments, excluding only malformed and undumpable
segments.
Unlike the default invocation, this flag dumps mappings of devices which
may invalidate the state of device transactions or trigger other unexpected
behavior.
As a result, this flag should only be used when the behavior of the
application and any devices it has mapped is fully understood and any side
effects can be controlled or tolerated.
.It Fl k
Use the
.Xr ptrace 2
.Dv PT_COREDUMP
kernel facility to write the core dump, instead of reading the process'
memory and constructing the dump file in
.Nm
itself.
This is faster, and the dump is written by the
same kernel code that writes core dumps upon fatal signals.
.El
.Sh FILES
.Bl -tag -width /var/log/messages -compact
.It Pa core.<pid>
the core image
.El
.Sh HISTORY
A
.Nm
utility appeared in
.Bx 4.2 .
.Sh BUGS
Because of the
.Xr ptrace 2
usage
.Nm
may not work with processes which are actively being investigated with
.Xr truss 1
or
.Xr gdb 1 .
Additionally, interruptable sleeps may exit with EINTR.
.Pp
The
.Nm
utility is not compatible with the original
.Bx 4.2
version.
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.\" Copyright (c) 1983, 1990, 1992, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96 2017-02-28 23:42:47 +00:00			`.\" 3. Neither the name of the University nor the names of its contributors`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
			`.\" @(#)gcore.1 8.2 (Berkeley) 4/18/94`
$Id$ -> $FreeBSD$ 1999-08-28 01:08:13 +00:00			`.\" $FreeBSD$`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.\"`
gcore: add option to dump core using kernel facility -k switch causes gcore to use ptrace(PT_COREDUMP) instead of manually reading process memory and constructing the core. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D29955 2021-04-24 11:20:24 +00:00			`.Dd April 24, 2021`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Dt GCORE 1`
mdoc(7) police: removed HISTORY info from the .Os call. 2001-07-10 14:16:33 +00:00			`.Os`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Sh NAME`
			`.Nm gcore`
			`.Nd get core images of running process`
			`.Sh SYNOPSIS`
Remove whitespace at EOL. 2001-07-15 08:06:20 +00:00			`.Nm`
Fix the way the segments are included in the gcore outputs (with the default invokation): - Right now if segments are not writable are not included. Remove this. - Right now if a segment is mapped with NOCORE the check is not honoured. Change this by checking the newly added flag, from libutil, KVME_FLAG_NOCOREDUMP. Besides that, add a new flag (-f) that forces a 'full' dump of all the segments excluding just the malformed ones. This might be used very carefully as, among the reported segments, there could be memory mapped areas that could be vital to program execution. Sponsored by: Sandvine Incorporated Discussed with: kib Reviewed by: emaste Tested by: Sandvine Incorporated MFC after: 2 weeks 2010-07-14 17:16:25 +00:00			`.Op Fl f`
gcore: add option to dump core using kernel facility -k switch causes gcore to use ptrace(PT_COREDUMP) instead of manually reading process memory and constructing the core. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D29955 2021-04-24 11:20:24 +00:00			`.Op Fl k`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Op Fl c Ar core`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`.Op Ar executable`
Don't require an executable file name. If no executable image is specified, use /proc/<pid>/file. Document it. PR: bin/7915 Suggested-By: Wolfram Schneider <wosch@panke.de.freebsd.org> 1998-09-14 10:09:30 +00:00			`.Ar pid`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Sh DESCRIPTION`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`The`
			`.Nm`
			`utility creates a core image of the specified process,`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`suitable for use with`
Deal with double whitespace. 2004-07-03 00:24:45 +00:00			`.Xr gdb 1 .`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`By default, the core is written to the file`
			`.Dq Pa core.<pid> .`
Don't require an executable file name. If no executable image is specified, use /proc/<pid>/file. Document it. PR: bin/7915 Suggested-By: Wolfram Schneider <wosch@panke.de.freebsd.org> 1998-09-14 10:09:30 +00:00			`The process identifier,`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Ar pid ,`
Remove single-space hard sentence breaks. These degrade the quality of the typeset output, tend to make diffs harder to read and provide bad examples for new-comers to mdoc. 2000-03-01 12:20:22 +00:00			`must be given on the command line.`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Pp`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`The following options are available:`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Bl -tag -width indent`
			`.It Fl c`
			`Write the core file to the specified file instead of`
			`.Dq Pa core.<pid> .`
Fix the way the segments are included in the gcore outputs (with the default invokation): - Right now if segments are not writable are not included. Remove this. - Right now if a segment is mapped with NOCORE the check is not honoured. Change this by checking the newly added flag, from libutil, KVME_FLAG_NOCOREDUMP. Besides that, add a new flag (-f) that forces a 'full' dump of all the segments excluding just the malformed ones. This might be used very carefully as, among the reported segments, there could be memory mapped areas that could be vital to program execution. Sponsored by: Sandvine Incorporated Discussed with: kib Reviewed by: emaste Tested by: Sandvine Incorporated MFC after: 2 weeks 2010-07-14 17:16:25 +00:00			`.It Fl f`
gcore: add option to dump core using kernel facility -k switch causes gcore to use ptrace(PT_COREDUMP) instead of manually reading process memory and constructing the core. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D29955 2021-04-24 11:20:24 +00:00			`Dumps all available segments, excluding only malformed and undumpable`
			`segments.`
Start sentences on a new line to ease life for translators. Tweak the wording in a few places. MFC after: 1 week 2010-12-28 18:58:15 +00:00			`Unlike the default invocation, this flag dumps mappings of devices which`
			`may invalidate the state of device transactions or trigger other unexpected`
			`behavior.`
			`As a result, this flag should only be used when the behavior of the`
			`application and any devices it has mapped is fully understood and any side`
			`effects can be controlled or tolerated.`
gcore: add option to dump core using kernel facility -k switch causes gcore to use ptrace(PT_COREDUMP) instead of manually reading process memory and constructing the core. Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D29955 2021-04-24 11:20:24 +00:00			`.It Fl k`
			`Use the`
			`.Xr ptrace 2`
			`.Dv PT_COREDUMP`
			`kernel facility to write the core dump, instead of reading the process'`
			`memory and constructing the dump file in`
			`.Nm`
			`itself.`
			`This is faster, and the dump is written by the`
			`same kernel code that writes core dumps upon fatal signals.`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.El`
			`.Sh FILES`
			`.Bl -tag -width /var/log/messages -compact`
			`.It Pa core.<pid>`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`the core image`
Fixed typo: .EL -> .El 2000-11-06 09:20:09 +00:00			`.El`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Sh HISTORY`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`A`
			`.Nm`
			`utility appeared in`
Use the .Bx macro where appropriate. 1996-08-23 20:36:11 +00:00			`.Bx 4.2 .`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Sh BUGS`
Change gcore in order to get rid of the procfs accesses and use FreeBSD's specific sysctls and ptrace interfaces. This change switches a bit gcore POLA that is summarized here: - now gcore can recognize threads within the process and handle dumps on thread-scope - the process to be analyzed will be stopped during its gcore run - gcore may not work with processes which are actively being analyzed by gdb or truss - the ptrace interface may cause syscalls to return EINTR, thus interferring with signals handling within the process Side note: <janitor task> the interface can be further lifted in order to get rid of the very last procfs interfaces remnants and made more suitable for copying with sysctl/ptrace interface </janitor task>. Obtained from: Sandvine Incorporated Reviewed by: emaste, rwatson Sponsored by: Sandvine Incorporated MFC: 1 month 2009-11-25 15:23:14 +00:00			`Because of the`
			`.Xr ptrace 2`
			`usage`
Use err(3) instead of local redefinition. 1997-07-08 11:04:19 +00:00			`.Nm`
Start sentences on a new line to ease life for translators. Tweak the wording in a few places. MFC after: 1 week 2010-12-28 18:58:15 +00:00			`may not work with processes which are actively being investigated with`
Change gcore in order to get rid of the procfs accesses and use FreeBSD's specific sysctls and ptrace interfaces. This change switches a bit gcore POLA that is summarized here: - now gcore can recognize threads within the process and handle dumps on thread-scope - the process to be analyzed will be stopped during its gcore run - gcore may not work with processes which are actively being analyzed by gdb or truss - the ptrace interface may cause syscalls to return EINTR, thus interferring with signals handling within the process Side note: <janitor task> the interface can be further lifted in order to get rid of the very last procfs interfaces remnants and made more suitable for copying with sysctl/ptrace interface </janitor task>. Obtained from: Sandvine Incorporated Reviewed by: emaste, rwatson Sponsored by: Sandvine Incorporated MFC: 1 month 2009-11-25 15:23:14 +00:00			`.Xr truss 1`
			`or`
			`.Xr gdb 1 .`
			`Additionally, interruptable sleeps may exit with EINTR.`
BSD 4.4 Lite Usr.bin Sources 1994-05-27 12:33:43 +00:00			`.Pp`
Use `The .Nm utility' 2002-04-19 23:44:58 +00:00			`The`
			`.Nm`
			`utility is not compatible with the original`
Remove whitespace at EOL. 2001-07-15 08:06:20 +00:00			`.Bx 4.2`
Use the .Bx macro where appropriate. 1996-08-23 20:36:11 +00:00			`version.`