systemd/man/systemd-coredump.xml

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<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>Log and store 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> can be used as a helper
    binary by the kernel when a user space program receives a fatal
    signal and dumps core. For it to be used in this capacity, it must
    be specified by the
    <varname>kernel.core_pattern</varname> <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    setting. The syntax of this setting is explained in
    <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    Systemd installs <filename>/usr/lib/sysctl.d/50-coredump.conf</filename> which configures
    <varname>kernel.core_pattern</varname> to invoke <command>systemd-coredump</command>.
    This file may be masked or overridden to use a different setting following normal
    <citerefentry><refentrytitle>sysctl.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    rules.</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 coredump will only be processed when the
    related resource limits are high enough. For programs started by
    <command>systemd</command>, those may be set using
    <varname>LimitCore=</varname> (see
    <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
    </para>

    <para>The behaviour of <command>systemd-coredump</command> is configured through
    <filename>/etc/systemd/coredump.conf</filename> and other configuration files. See
    <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    for details. By default, <command>systemd-coredump</command> will log the coredump including a
    backtrace if possible, and store the core (contents of process' memory contents) in an external
    file on disk in <filename>/var/lib/systemd/coredump</filename>.</para>

    <para>When the kernel invokes <command>systemd-coredump</command> to handle a coredump,
    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 coredump. Hence <filename>systemd-coredump.socket</filename>
    and <filename>systemd-coredump@.service</filename> are helper units which do the actual
    processing of coredumps and are subject to normal service management.</para>

    <para>The log entry and a backtrace are stored in the journal, and can be viewed with
    <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
    <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    may be used to list and extract coredumps or load them in
    <citerefentry project='man-pages'><refentrytitle>gdb</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
    </para>

    <para>The coredump helper is invoked anew each time. Therefore, any configuration
    changes will take effect on the invocation of <command>systemd-coredump</command>.
    If the sysctl configuration is modified, it must be updated in the kernel before
    it takes effect, see
    <citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    and
    <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    </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 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>