128 lines
6.2 KiB
XML
128 lines
6.2 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2014 Zbigniew Jędrzejewski-Szmek
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd-coredump" conditional='ENABLE_COREDUMP'
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>systemd-coredump</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd-coredump</refentrytitle>
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<manvolnum>8</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd-coredump</refname>
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<refname>systemd-coredump.socket</refname>
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<refname>systemd-coredump@.service</refname>
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<refpurpose>Log and store core dumps</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>/usr/lib/systemd/systemd-coredump</filename></para>
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<para><filename>systemd-coredump@.service</filename></para>
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<para><filename>systemd-coredump.socket</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>systemd-coredump</command> can be used as a helper
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binary by the kernel when a user space program receives a fatal
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signal and dumps core. For it to be used in this capacity, it must
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be specified by the
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<varname>kernel.core_pattern</varname> <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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setting. The syntax of this setting is explained in
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<citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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Systemd installs <filename>/usr/lib/sysctl.d/50-coredump.conf</filename> which configures
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<varname>kernel.core_pattern</varname> to invoke <command>systemd-coredump</command>.
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This file may be masked or overridden to use a different setting following normal
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<citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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rules.</para>
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<para>The behavior of a specific program upon reception of a
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signal is governed by a few factors which are described in detail
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in <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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In particular, the coredump will only be processed when the
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related resource limits are high enough. For programs started by
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<command>systemd</command>, those may be set using
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<varname>LimitCore=</varname> (see
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
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</para>
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<para>The behaviour of <command>systemd-coredump</command> is configured through
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<filename>/etc/systemd/coredump.conf</filename> and other configuration files. See
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<citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details. By default, <command>systemd-coredump</command> will log the coredump including a
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backtrace if possible, and store the core (contents of process' memory contents) in an external
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file on disk in <filename>/var/lib/systemd/coredump</filename>.</para>
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<para>When the kernel invokes <command>systemd-coredump</command> to handle a coredump,
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it will connect to the socket created by the <filename>systemd-coredump.socket</filename>
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unit, which in turn will spawn a <filename>systemd-coredump@.service</filename> instance
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to process the coredump. Hence <filename>systemd-coredump.socket</filename>
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and <filename>systemd-coredump@.service</filename> are helper units which do the actual
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processing of coredumps and are subject to normal service management.</para>
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<para>The log entry and a backtrace are stored in the journal, and can be viewed with
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
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<citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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may be used to list and extract coredumps or load them in
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<citerefentry project='man-pages'><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
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</para>
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<para>The coredump helper is invoked anew each time. Therefore, any configuration
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changes will take effect on the invocation of <command>systemd-coredump</command>.
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If the sysctl configuration is modified, it must be updated in the kernel before
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it takes effect, see
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<citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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and
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<citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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</para>
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</refsect1>
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</refentry>
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