coredump: Improve man pages

man/coredump.conf.xml

@@ -45,7 +45,7 @@
   <refnamediv>
     <refname>coredump.conf</refname>
     <refname>coredump.conf.d</refname>
-    <refpurpose>Coredump storage configuration files</refpurpose>
+    <refpurpose>Core dump storage configuration files</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
@@ -86,7 +86,7 @@
         <listitem><para>Controls where to store cores. One of
         <literal>none</literal>, <literal>external</literal>,
         <literal>journal</literal>, and <literal>both</literal>. When
-        <literal>none</literal>, the coredumps will be logged but not
+        <literal>none</literal>, the core dumps will be logged but not
         stored permanently. When <literal>external</literal> (the
         default), cores will be stored in <filename>/var/lib/systemd/coredump</filename>.
         When <literal>journal</literal>, cores will be stored in
@@ -114,7 +114,7 @@
         <term><varname>ProcessSizeMax=</varname></term>
 
         <listitem><para>The maximum size in bytes of a core
-        which will be processed. Coredumps exceeding this size
+        which will be processed. Core dumps exceeding this size
         will be logged, but the backtrace will not be generated
         and the core will not be stored.</para></listitem>
       </varlistentry>
@@ -132,14 +132,14 @@
         <term><varname>KeepFree=</varname></term>
 
         <listitem><para>Enforce limits on the disk space taken up by
-        externally stored coredumps. <option>MaxUse=</option> makes
+        externally stored core dumps. <option>MaxUse=</option> makes
-        sure that old coredumps are removed as soon as the total disk
+        sure that old core dumps are removed as soon as the total disk
-        space taken up by coredumps grows beyond this limit (defaults
+        space taken up by core dumps grows beyond this limit (defaults
         to 10% of the total disk size). <option>KeepFree=</option>
         controls how much disk space to keep free at least (defaults
         to 15% of the total disk size). Note that the disk space used
-        by coredumps might temporarily exceed these limits while
+        by core dumps might temporarily exceed these limits while
-        coredumps are processed. Note that old coredumps are also
+        core dumps are processed. Note that old core dumps are also
         removed based on time via
         <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>. Set
         either value to 0 to turn off size-based

man/coredumpctl.xml

@@ -45,7 +45,7 @@
 
   <refnamediv>
     <refname>coredumpctl</refname>
-    <refpurpose>Retrieve coredumps from the journal</refpurpose>
+    <refpurpose>Retrieve and process saved core dumps and metadata</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
@@ -60,9 +60,10 @@
   <refsect1>
     <title>Description</title>
 
-    <para><command>coredumpctl</command> may be used to
+    <para><command>coredumpctl</command> is a tool that can be used to retrieve and process core
-    retrieve coredumps from
+    dumps and metadata which were saved by
-    <citerefentry><refentrytitle>systemd-journald</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
+    <citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+    </para>
   </refsect1>
 
   <refsect1>
@@ -71,18 +72,23 @@
     <para>The following options are understood:</para>
 
     <variablelist>
+
+      <xi:include href="standard-options.xml" xpointer="help" />
+      <xi:include href="standard-options.xml" xpointer="version" />
+
       <varlistentry>
         <term><option>--no-legend</option></term>
 
-        <listitem><para>Do not print column headers.
+        <listitem><para>Do not print column headers.</para></listitem>
-        </para></listitem>
       </varlistentry>
 
+      <xi:include href="standard-options.xml" xpointer="no-pager" />
+
       <varlistentry>
         <term><option>-1</option></term>
 
-        <listitem><para>Show information of a single coredump only,
+        <listitem><para>Show information of a single core dump only, instead of listing
-        instead of listing all known coredumps. </para></listitem>
+        all known core dumps.</para></listitem>
       </varlistentry>
 
       <varlistentry>
@@ -90,7 +96,7 @@
         <term><option>--field=</option><replaceable>FIELD</replaceable></term>
 
         <listitem><para>Print all possible data values the specified
-        field takes in matching coredump entries of the
+        field takes in matching core dump entries of the
         journal.</para></listitem>
       </varlistentry>
 
@@ -110,11 +116,11 @@
         </para></listitem>
       </varlistentry>
 
-      <xi:include href="standard-options.xml" xpointer="help" />
-      <xi:include href="standard-options.xml" xpointer="version" />
-      <xi:include href="standard-options.xml" xpointer="no-pager" />
-
     </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Commands</title>
 
     <para>The following commands are understood:</para>
 
@@ -122,23 +128,31 @@
       <varlistentry>
         <term><command>list</command></term>
 
-        <listitem><para>List coredumps captured in the journal
+        <listitem><para>List core dumps captured in the journal
         matching specified characteristics. If no command is
-        specified, this is the implied default.</para></listitem>
+        specified, this is the implied default.</para>
+
+        <para>It's worth noting that different restrictions apply to
+        data saved in the journal and core dump files saved in
+        <filename>/var/lib/systemd/coredump</filename>, see overview in
+        <citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+        Thus it may very well happen that a particular core dump is still listed
+        in the journal while its corresponding core dump file has already been
+        removed.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><command>info</command></term>
 
-        <listitem><para>Show detailed information about coredumps
+        <listitem><para>Show detailed information about core dumps
         captured in the journal.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><command>dump</command></term>
 
-        <listitem><para>Extract the last coredump matching specified
+        <listitem><para>Extract the last core dump matching specified
-        characteristics. The coredump will be written on standard
+        characteristics. The core dump will be written on standard
         output, unless an output file is specified with
         <option>--output=</option>. </para></listitem>
       </varlistentry>
@@ -146,7 +160,7 @@
       <varlistentry>
         <term><command>gdb</command></term>
 
-        <listitem><para>Invoke the GNU debugger on the last coredump
+        <listitem><para>Invoke the GNU debugger on the last core dump
         matching specified characteristics. </para></listitem>
       </varlistentry>
 
@@ -197,7 +211,7 @@
   <refsect1>
     <title>Exit status</title>
     <para>On success, 0 is returned; otherwise, a non-zero failure
-    code is returned. Not finding any matching coredumps is treated as
+    code is returned. Not finding any matching core dumps is treated as
     failure.
     </para>
   </refsect1>
@@ -206,13 +220,13 @@
     <title>Examples</title>
 
     <example>
-      <title>List all the coredumps of a program named foo</title>
+      <title>List all the core dumps of a program named foo</title>
 
       <programlisting># coredumpctl list foo</programlisting>
     </example>
 
     <example>
-      <title>Invoke gdb on the last coredump</title>
+      <title>Invoke gdb on the last core dump</title>
 
       <programlisting># coredumpctl gdb</programlisting>
     </example>
@@ -225,7 +239,7 @@
     </example>
 
     <example>
-      <title>Extract the last coredump of /usr/bin/bar to a file named
+      <title>Extract the last core dump of /usr/bin/bar to a file named
       <filename noindex="true">bar.coredump</filename></title>
 
       <programlisting># coredumpctl -o bar.coredump dump /usr/bin/bar</programlisting>

man/systemd-coredump.xml

@@ -47,7 +47,7 @@
     <refname>systemd-coredump</refname>
     <refname>systemd-coredump.socket</refname>
     <refname>systemd-coredump@.service</refname>
-    <refpurpose>Log and store core dumps</refpurpose>
+    <refpurpose>Acquire, save and process core dumps</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
@@ -58,59 +58,76 @@
 
   <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><command>systemd-coredump</command> can be used as a helper
+    <para>Core dumps can be written to the journal or saved as a file. Once saved they can be retrieved
-    binary by the kernel when a user space program receives a fatal
+    for further processing, for example in
-    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
+    <para>By default, <command>systemd-coredump</command> will log the core dump including a backtrace
-    changes will take effect on the invocation of <command>systemd-coredump</command>.
+    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><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+    <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
     and
-    <citerefentry project='man-pages'><refentrytitle>sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
+    <citerefentry><refentrytitle>systemd-sysctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
     </para>
+
+    <para>The behaviour 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>
@@ -119,6 +136,7 @@
       <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>.