<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2014 Zbigniew Jędrzejewski-Szmek systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="systemd-coredump" conditional='ENABLE_COREDUMP' xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>systemd-coredump</title> <productname>systemd</productname> <authorgroup> <author> <contrib>Developer</contrib> <firstname>Lennart</firstname> <surname>Poettering</surname> <email>lennart@poettering.net</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>systemd-coredump</refentrytitle> <manvolnum>8</manvolnum> </refmeta> <refnamediv> <refname>systemd-coredump</refname> <refname>systemd-coredump.socket</refname> <refname>systemd-coredump@.service</refname> <refpurpose>Acquire, save and process core dumps</refpurpose> </refnamediv> <refsynopsisdiv> <para><filename>/usr/lib/systemd/systemd-coredump</filename></para> <para><filename>systemd-coredump@.service</filename></para> <para><filename>systemd-coredump.socket</filename></para> </refsynopsisdiv> <refsect1> <title>Description</title> <para><command>systemd-coredump</command> is a system service that can acquire core dumps from the kernel and handle them in various ways.</para> <para>Core dumps can be written to the journal or saved as a file. Once saved they can be retrieved for further processing, for example in <citerefentry project='man-pages'><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry>. </para> <para>By default, <command>systemd-coredump</command> will log the core dump including a backtrace if possible to the journal and store the core dump itself in an external file in <filename>/var/lib/systemd/coredump</filename>.</para> <para>When the kernel invokes <command>systemd-coredump</command> to handle a core dump, it will connect to the socket created by the <filename>systemd-coredump.socket</filename> unit, which in turn will spawn a <filename>systemd-coredump@.service</filename> instance to process the core dump. Hence <filename>systemd-coredump.socket</filename> and <filename>systemd-coredump@.service</filename> are helper units which do the actual processing of core dumps and are subject to normal service management.</para> <para>The behavior of a specific program upon reception of a signal is governed by a few factors which are described in detail in <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>. In particular, the core dump will only be processed when the related resource limits are sufficient. </para> </refsect1> <refsect1> <title>Configuration</title> <para>For programs started by <command>systemd</command> process resource limits can be set by directive <varname>LimitCore=</varname>, see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. </para> <para>In order to be used <command>systemd-coredump</command> must be configured in <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> parameter <varname>kernel.core_pattern</varname>. The syntax of this parameter is explained in <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Systemd installs the file <filename>/usr/lib/sysctl.d/50-coredump.conf</filename> which configures <varname>kernel.core_pattern</varname> accordingly. This file may be masked or overridden to use a different setting following normal <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> rules. If the sysctl configuration is modified, it must be updated in the kernel before it takes effect, see <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry> and <citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>. </para> <para>The behavior of <command>systemd-coredump</command> itself is configured through the configuration file <filename>/etc/systemd/coredump.conf</filename> and corresponding snippets <filename>/etc/systemd/coredump.conf.d/*.conf</filename>, see <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A new instance of <command>systemd-coredump</command> is invoked upon receiving every core dump. Therefore, changes in these files will take effect the next time a core dump is received.</para> <para>Resources used by core dump files are restricted in two ways. Parameters like maximum size of acquired core dumps and files can be set in files <filename>/etc/systemd/coredump.conf</filename> and snippets mentioned above. In addition the storage time of core dump files is restricted by <command>systemd-tmpfiles</command>, corresponding settings are by default in <filename>/usr/lib/tmpfiles.d/systemd.conf</filename>.</para> </refsect1> <refsect1> <title>Usage</title> <para>Data stored in the journal can be viewed with <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> as usual. <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> can be used to retrieve saved core dumps independent of their location, to display information and to process them e.g. by passing to the GNU debugger (gdb).</para> </refsect1> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>, <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. </para> </refsect1> </refentry>