man/systemd-coredump.xml

   1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   This file is part of systemd.
   7
   8   Copyright 2014 Zbigniew Jędrzejewski-Szmek
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="systemd-coredump" conditional='ENABLE_COREDUMP'
  25           xmlns:xi="http://www.w3.org/2001/XInclude">
  26
  27   <refentryinfo>
  28     <title>systemd-coredump</title>
  29     <productname>systemd</productname>
  30
  31     <authorgroup>
  32       <author>
  33         <contrib>Developer</contrib>
  34         <firstname>Lennart</firstname>
  35         <surname>Poettering</surname>
  36         <email>lennart@poettering.net</email>
  37       </author>
  38     </authorgroup>
  39   </refentryinfo>
  40
  41   <refmeta>
  42     <refentrytitle>systemd-coredump</refentrytitle>
  43     <manvolnum>8</manvolnum>
  44   </refmeta>
  45
  46   <refnamediv>
  47     <refname>systemd-coredump</refname>
  48     <refname>systemd-coredump.socket</refname>
  49     <refname>systemd-coredump@.service</refname>
  50     <refpurpose>Acquire, save and process core dumps</refpurpose>
  51   </refnamediv>
  52
  53   <refsynopsisdiv>
  54     <para><filename>/usr/lib/systemd/systemd-coredump</filename></para>
  55     <para><filename>systemd-coredump@.service</filename></para>
  56     <para><filename>systemd-coredump.socket</filename></para>
  57   </refsynopsisdiv>
  58
  59   <refsect1>
  60     <title>Description</title>
  61     <para><command>systemd-coredump</command> is a system service that can acquire core dumps
  62     from the kernel and handle them in various ways.</para>
  63
  64     <para>Core dumps can be written to the journal or saved as a file. Once saved they can be retrieved
  65     for further processing, for example in
  66     <citerefentry project='man-pages'><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
  67     </para>
  68
  69     <para>By default, <command>systemd-coredump</command> will log the core dump including a backtrace
  70     if possible to the journal and store the core dump itself in an external file in
  71     <filename>/var/lib/systemd/coredump</filename>.</para>
  72
  73     <para>When the kernel invokes <command>systemd-coredump</command> to handle a core dump,
  74     it will connect to the socket created by the <filename>systemd-coredump.socket</filename>
  75     unit, which in turn will spawn a <filename>systemd-coredump@.service</filename> instance
  76     to process the core dump. Hence <filename>systemd-coredump.socket</filename>
  77     and <filename>systemd-coredump@.service</filename> are helper units which do the actual
  78     processing of core dumps and are subject to normal service management.</para>
  79
  80     <para>The behavior of a specific program upon reception of a signal is governed by a few
  81     factors which are described in detail in
  82     <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
  83     In particular, the core dump will only be processed when the related resource limits are sufficient.
  84     </para>
  85   </refsect1>
  86
  87   <refsect1>
  88     <title>Configuration</title>
  89     <para>For programs started by <command>systemd</command> process resource limits can be set by directive
  90     <varname>LimitCore=</varname>, see
  91     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
  92     </para>
  93
  94     <para>In order to be used <command>systemd-coredump</command> must be configured in
  95     <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  96     parameter <varname>kernel.core_pattern</varname>. The syntax of this parameter is explained in
  97     <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
  98     Systemd installs the file <filename>/usr/lib/sysctl.d/50-coredump.conf</filename> which configures
  99     <varname>kernel.core_pattern</varname> accordingly. This file may be masked or overridden to use a different
 100     setting following normal
 101     <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 102     rules.
 103     If the sysctl configuration is modified, it must be updated in the kernel before
 104     it takes effect, see
 105     <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 106     and
 107     <citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 108     </para>
 109
 110     <para>The behaviour of <command>systemd-coredump</command> itself is configured through the configuration file
 111     <filename>/etc/systemd/coredump.conf</filename> and corresponding snippets
 112     <filename>/etc/systemd/coredump.conf.d/*.conf</filename>, see
 113     <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>. A new
 114     instance of <command>systemd-coredump</command> is invoked upon receiving every core dump. Therefore, changes
 115     in these files will take effect the next time a core dump is received.</para>
 116
 117     <para>Resources used by core dump files are restricted in two ways. Parameters like maximum size of acquired
 118     core dumps and files can be set in files <filename>/etc/systemd/coredump.conf</filename> and snippets mentioned
 119     above. In addition the storage time of core dump files is restricted by <command>systemd-tmpfiles</command>,
 120     corresponding settings are by default in <filename>/usr/lib/tmpfiles.d/systemd.conf</filename>.</para>
 121   </refsect1>
 122
 123   <refsect1>
 124     <title>Usage</title>
 125     <para>Data stored in the journal can be viewed with
 126     <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 127     as usual.
 128     <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 129     can be used to retrieve saved core dumps independent of their location, to display information and to process
 130     them e.g. by passing to the GNU debugger (gdb).</para>
 131   </refsect1>
 132
 133   <refsect1>
 134     <title>See Also</title>
 135     <para>
 136       <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 137       <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 138       <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 139       <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 140       <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 141       <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 142       <citerefentry><refentrytitle>systemd-sysctl.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 143     </para>
 144   </refsect1>
 145 </refentry>