[thirdparty/systemd.git] / man / journalctl.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="journalctl"
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>journalctl</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>journalctl</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>journalctl</refname>
    <refpurpose>Print log entries from the systemd journal</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>journalctl</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="opt" rep="repeat">MATCHES</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>journalctl</command> is used to print the log entries stored in the journal by
    <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    and
    <citerefentry><refentrytitle>systemd-journal-remote.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    </para>

    <para>If called without parameters, it will show the contents of the journal accessible to the calling
    user, starting with the oldest entry collected.</para>

    <para>If one or more match arguments are passed, the output is filtered accordingly. A match is in the
    format <literal>FIELD=VALUE</literal>, e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>, referring to
    the components of a structured journal entry. See
    <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    for a list of well-known fields. If multiple matches are specified matching different fields, the log
    entries are filtered by both, i.e. the resulting output will show only entries matching all the specified
    matches of this kind. If two matches apply to the same field, then they are automatically matched as
    alternatives, i.e. the resulting output will show entries matching any of the specified matches for the
    same field. Finally, the character <literal>+</literal> may appear as a separate word between other terms
    on the command line. This causes all matches before and after to be combined in a disjunction
    (i.e. logical OR).</para>

    <para>It is also possible to filter the entries by specifying an absolute file path as an argument. The
    file path may be a file or a symbolic link and the file must exist at the time of the query. If a file
    path refers to an executable binary, an <literal>_EXE=</literal> match for the canonicalized binary path
    is added to the query. If a file path refers to an executable script, a <literal>_COMM=</literal> match
    for the script name is added to the query. If a file path refers to a device node,
    <literal>_KERNEL_DEVICE=</literal> matches for the kernel name of the device and for each of its ancestor
    devices is added to the query. Symbolic links are dereferenced, kernel names are synthesized, and parent
    devices are identified from the environment at the time of the query. In general, a device node is the
    best proxy for an actual device, as log entries do not usually contain fields that identify an actual
    device. For the resulting log entries to be correct for the actual device, the relevant parts of the
    environment at the time the entry was logged, in particular the actual device corresponding to the device
    node, must have been the same as those at the time of the query. Because device nodes generally change
    their corresponding devices across reboots, specifying a device node path causes the resulting entries to
    be restricted to those from the current boot.</para>

    <para>Additional constraints may be added using options <option>--boot</option>,
    <option>--unit=</option>, etc., to further limit what entries will be shown (logical AND).</para>

    <para>Output is interleaved from all accessible journal files, whether they are rotated or currently
    being written, and regardless of whether they belong to the system itself or are accessible user
    journals. The <option>--header</option> option can be used to identify which files
    <emphasis>are</emphasis> being shown.</para>

    <para>The set of journal files which will be used can be modified using the <option>--user</option>,
    <option>--system</option>, <option>--directory=</option>, and <option>--file=</option> options, see
    below.</para>

    <para>All users are granted access to their private per-user journals. However, by default, only root and
    users who are members of a few special groups are granted access to the system journal and the journals
    of other users. Members of the groups <literal>systemd-journal</literal>, <literal>adm</literal>, and
    <literal>wheel</literal> can read all journal files. Note that the two latter groups traditionally have
    additional privileges specified by the distribution. Members of the <literal>wheel</literal> group can
    often perform administrative tasks.</para>

    <para>The output is paged through <command>less</command> by default, and long lines are "truncated" to
    screen width. The hidden part can be viewed by using the left-arrow and right-arrow keys. Paging can be
    disabled; see the <option>--no-pager</option> option and the "Environment" section below.</para>

    <para>When outputting to a tty, lines are colored according to priority: lines of level ERROR and higher
    are colored red; lines of level WARNING are colored yellow; lines of level NOTICE are highlighted;
    lines of level INFO are displayed normally; lines of level DEBUG are colored grey.</para>

    <para>To write entries <emphasis>to</emphasis> the journal, a few methods may be used. In general, output
    from systemd units is automatically connected to the journal, see
    <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    In addition,
    <citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    may be used to send messages to the journal directly.</para>
  </refsect1>

  <refsect1>
    <title>Source Options</title>

    <para>The following options control where to read journal records from:</para>

    <variablelist>
      <varlistentry>
        <term><option>--system</option></term>
        <term><option>--user</option></term>

        <listitem><para>Show messages from system services and the kernel (with
        <option>--system</option>). Show messages from service of current user (with
        <option>--user</option>).  If neither is specified, show all messages that the user can see.
        </para>

        <para>The <option>--user</option> option affects how <option>--unit=</option> arguments are
        treated. See <option>--unit=</option>.</para>

        <para>Note that <option>--user</option> only works if persistent logging is enabled, via the
        <varname>Storage=</varname> setting in
        <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

        <xi:include href="version-info.xml" xpointer="v205"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-M</option></term>
        <term><option>--machine=</option></term>

        <listitem><para>Show messages from a running, local container. Specify a container name to connect
        to.</para>

        <xi:include href="version-info.xml" xpointer="v209"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-m</option></term>
        <term><option>--merge</option></term>

        <listitem><para>Show entries interleaved from all available journals, including remote
        ones.</para>

        <xi:include href="version-info.xml" xpointer="v190"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-D <replaceable>DIR</replaceable></option></term>
        <term><option>--directory=<replaceable>DIR</replaceable></option></term>

        <listitem><para>Takes a directory path as argument. If specified, journalctl will operate on the
        specified journal directory <replaceable>DIR</replaceable> instead of the default runtime and system
        journal paths.</para>

        <xi:include href="version-info.xml" xpointer="v187"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-i <replaceable>GLOB</replaceable></option></term>
        <term><option>--file=<replaceable>GLOB</replaceable></option></term>

        <listitem><para>Takes a file glob as an argument. If specified, journalctl will operate on the
        specified journal files matching <replaceable>GLOB</replaceable> instead of the default runtime and
        system journal paths. May be specified multiple times, in which case files will be suitably
        interleaved.</para>

        <xi:include href="version-info.xml" xpointer="v205"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--root=<replaceable>ROOT</replaceable></option></term>

        <listitem><para>Takes a directory path as an argument. If specified, <command>journalctl</command>
        will operate on journal directories and catalog file hierarchy underneath the specified directory
        instead of the root directory (e.g. <option>--update-catalog</option> will create
        <filename><replaceable>ROOT</replaceable>/var/lib/systemd/catalog/database</filename>, and journal
        files under <filename><replaceable>ROOT</replaceable>/run/journal/</filename> or
        <filename><replaceable>ROOT</replaceable>/var/log/journal/</filename> will be displayed).
        </para>

        <xi:include href="version-info.xml" xpointer="v201"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--image=<replaceable>IMAGE</replaceable></option></term>

        <listitem><para>Takes a path to a disk image file or block device node. If specified,
        <command>journalctl</command> will operate on the file system in the indicated disk image. This
        option is similar to <option>--root=</option>, but operates on file systems stored in disk images or
        block devices, thus providing an easy way to extract log data from disk images. The disk image should
        either contain just a file system or a set of file systems within a GPT partition table, following
        the <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">Discoverable Partitions
        Specification</ulink>. For further information on supported disk images, see
        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
        switch of the same name.</para>

        <xi:include href="version-info.xml" xpointer="v247"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="image-policy-open" />

      <varlistentry>
        <term><option>--namespace=<replaceable>NAMESPACE</replaceable></option></term>

        <listitem><para>Takes a journal namespace identifier string as argument. If not specified the data
        collected by the default namespace is shown. If specified shows the log data of the specified
        namespace instead. If the namespace is specified as <literal>*</literal> data from all namespaces is
        shown, interleaved. If the namespace identifier is prefixed with <literal>+</literal> data from the
        specified namespace and the default namespace is shown, interleaved, but no other. For details about
        journal namespaces see
        <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Filtering Options</title>

    <para>The following options control how to filter journal records:</para>

    <variablelist>
      <varlistentry>
        <term><option>-S</option></term>
        <term><option>--since=</option></term>
        <term><option>-U</option></term>
        <term><option>--until=</option></term>

        <listitem><para>Start showing entries on or newer than the specified date, or on or older than the
        specified date, respectively. Date specifications should be of the format <literal>2012-10-30
        18:17:16</literal>.  If the time part is omitted, <literal>00:00:00</literal> is assumed.  If only
        the seconds component is omitted, <literal>:00</literal> is assumed. If the date component is
        omitted, the current day is assumed. Alternatively the strings <literal>yesterday</literal>,
        <literal>today</literal>, <literal>tomorrow</literal> are understood, which refer to 00:00:00 of the
        day before the current day, the current day, or the day after the current day,
        respectively. <literal>now</literal> refers to the current time. Finally, relative times may be
        specified, prefixed with <literal>-</literal> or <literal>+</literal>, referring to times before or
        after the current time, respectively. For complete time and date specification, see
        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Note
        that <option>--output=short-full</option> prints timestamps that follow precisely this format.
        </para>

        <xi:include href="version-info.xml" xpointer="v195"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-c</option></term>
        <term><option>--cursor=</option></term>

        <listitem><para>Start showing entries from the location in the journal specified by the passed
        cursor.</para>

        <xi:include href="version-info.xml" xpointer="v193"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--after-cursor=</option></term>

        <listitem><para>Start showing entries from the location in the journal <emphasis>after</emphasis>
        the location specified by the passed cursor.  The cursor is shown when the
        <option>--show-cursor</option> option is used.</para>

        <xi:include href="version-info.xml" xpointer="v206"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--cursor-file=<replaceable>FILE</replaceable></option></term>

        <listitem><para>If <replaceable>FILE</replaceable> exists and contains a cursor, start showing
        entries <emphasis>after</emphasis> this location.  Otherwise show entries according to the other
        given options. At the end, write the cursor of the last entry to
        <replaceable>FILE</replaceable>. Use this option to continually read the journal by sequentially
        calling <command>journalctl</command>.</para>

        <xi:include href="version-info.xml" xpointer="v242"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-b <optional><optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>
        <term><option>--boot<optional>=<optional><replaceable>ID</replaceable></optional><optional><replaceable>±offset</replaceable></optional>|<constant>all</constant></optional></option></term>

        <listitem><para>Show messages from a specific boot. This will add a match for
        <literal>_BOOT_ID=</literal>.</para>

        <para>The argument may be empty, in which case logs for the current boot will be shown.</para>

        <para>If the boot ID is omitted, a positive <replaceable>offset</replaceable> will look up the boots
        starting from the beginning of the journal, and an equal-or-less-than zero
        <replaceable>offset</replaceable> will look up boots starting from the end of the journal. Thus,
        <constant>1</constant> means the first boot found in the journal in chronological order,
        <constant>2</constant> the second and so on; while <constant>-0</constant> is the last boot,
        <constant>-1</constant> the boot before last, and so on. An empty <replaceable>offset</replaceable>
        is equivalent to specifying <constant>-0</constant>, except when the current boot is not the last
        boot (e.g. because <option>--directory=</option> was specified to look at logs from a different
        machine).</para>

        <para>If the 32-character <replaceable>ID</replaceable> is specified, it may optionally be followed
        by <replaceable>offset</replaceable> which identifies the boot relative to the one given by boot
        <replaceable>ID</replaceable>. Negative values mean earlier boots and positive values mean later
        boots. If <replaceable>offset</replaceable> is not specified, a value of zero is assumed, and the
        logs for the boot given by <replaceable>ID</replaceable> are shown.</para>

        <para>The special argument <constant>all</constant> can be used to negate the effect of an earlier
        use of <option>-b</option>.</para>

        <xi:include href="version-info.xml" xpointer="v186"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-u</option></term>
        <term><option>--unit=<replaceable>UNIT</replaceable>|<replaceable>PATTERN</replaceable></option></term>

        <listitem><para>Show messages for the specified systemd unit <replaceable>UNIT</replaceable> (such as
        a service unit), or for any of the units matched by <replaceable>PATTERN</replaceable>.  If a pattern
        is specified, a list of unit names found in the journal is compared with the specified pattern and
        all that match are used. For each unit name, a match is added for messages from the unit
        (<literal>_SYSTEMD_UNIT=<replaceable>UNIT</replaceable></literal>), along with additional matches for
        messages from systemd and messages about coredumps for the specified unit. A match is also added for
        <literal>_SYSTEMD_SLICE=<replaceable>UNIT</replaceable></literal>, such that if the provided
        <replaceable>UNIT</replaceable> is a
        <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        unit, all logs of children of the slice will be shown.</para>

        <para>With <option>--user</option>, all <option>--unit=</option> arguments will be converted to match
        user messages as if specified with <option>--user-unit=</option>.</para>

        <para>This parameter can be specified multiple times.</para>

        <xi:include href="version-info.xml" xpointer="v195"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--user-unit=</option></term>

        <listitem><para>Show messages for the specified user session unit. This will add a match for messages
        from the unit (<literal>_SYSTEMD_USER_UNIT=</literal> and <literal>_UID=</literal>) and additional
        matches for messages from session systemd and messages about coredumps for the specified unit. A
        match is also added for <literal>_SYSTEMD_USER_SLICE=<replaceable>UNIT</replaceable></literal>, such
        that if the provided <replaceable>UNIT</replaceable> is a
        <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        unit, all logs of children of the unit will be shown.</para>

        <para>This parameter can be specified multiple times.</para>

        <xi:include href="version-info.xml" xpointer="v198"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-t</option></term>
        <term><option>--identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>

        <listitem><para>Show messages for the specified syslog identifier
        <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>

        <para>This parameter can be specified multiple times.</para>

        <xi:include href="version-info.xml" xpointer="v217"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-T</option></term>
        <term><option>--exclude-identifier=<replaceable>SYSLOG_IDENTIFIER</replaceable></option></term>

        <listitem><para>Exclude messages for the specified syslog identifier
        <replaceable>SYSLOG_IDENTIFIER</replaceable>.</para>

        <para>This parameter can be specified multiple times.</para>

        <xi:include href="version-info.xml" xpointer="v256"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-p</option></term>
        <term><option>--priority=</option></term>

        <listitem><para>Filter output by message priorities or priority ranges. Takes either a single numeric
        or textual log level (i.e. between 0/<literal>emerg</literal> and 7/<literal>debug</literal>), or a
        range of numeric/text log levels in the form FROM..TO. The log levels are the usual syslog log levels
        as documented in <citerefentry
        project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
        i.e. <literal>emerg</literal> (0), <literal>alert</literal> (1), <literal>crit</literal> (2),
        <literal>err</literal> (3), <literal>warning</literal> (4), <literal>notice</literal> (5),
        <literal>info</literal> (6), <literal>debug</literal> (7). If a single log level is specified, all
        messages with this log level or a lower (hence more important) log level are shown. If a range is
        specified, all messages within the range are shown, including both the start and the end value of the
        range. This will add <literal>PRIORITY=</literal> matches for the specified
        priorities.</para>

        <xi:include href="version-info.xml" xpointer="v188"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--facility=</option></term>

        <listitem><para>Filter output by syslog facility. Takes a comma-separated list of numbers or
        facility names. The names are the usual syslog facilities as documented in <citerefentry
        project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
        <option>--facility=help</option> may be used to display a list of known facility names and exit.
        </para>

        <xi:include href="version-info.xml" xpointer="v245"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-g</option></term>
        <term><option>--grep=</option></term>

        <listitem><para>Filter output to entries where the <varname>MESSAGE=</varname> field matches the
        specified regular expression. PERL-compatible regular expressions are used, see <citerefentry
        project='url'><refentrytitle
        url='http://pcre.org/current/doc/html/pcre2pattern.html'>pcre2pattern</refentrytitle><manvolnum>3</manvolnum></citerefentry>
        for a detailed description of the syntax.</para>

        <para>If the pattern is all lowercase, matching is case insensitive.  Otherwise, matching is case
        sensitive. This can be overridden with the <option>--case-sensitive</option> option, see
        below.</para>

        <para>When used with <option>--lines=</option> (not prefixed with <literal>+</literal>),
        <option>--reverse</option> is implied.</para>

        <xi:include href="version-info.xml" xpointer="v237"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--case-sensitive<optional>=BOOLEAN</optional></option></term>

        <listitem><para>Make pattern matching case sensitive or case insensitive.</para>

        <xi:include href="version-info.xml" xpointer="v237"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-k</option></term>
        <term><option>--dmesg</option></term>

        <listitem><para>Show only kernel messages. This implies <option>-b</option> and adds the match
        <literal>_TRANSPORT=kernel</literal>.</para>

        <xi:include href="version-info.xml" xpointer="v205"/></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Output Options</title>

    <para>The following options control how journal records are printed:</para>

    <variablelist>
      <varlistentry>
        <term><option>-o</option></term>
        <term><option>--output=</option></term>

        <listitem><para>Controls the formatting of the journal entries that are shown. Takes one of the
        following options:</para>

        <variablelist>
          <varlistentry>
            <term><option>short</option></term>
            <listitem><para>is the default and generates an output that is mostly identical to the
            formatting of classic syslog files, showing one line per journal entry.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-full</option></term>
            <listitem><para>is very similar, but shows timestamps in the format the
            <option>--since=</option> and <option>--until=</option> options accept. Unlike the timestamp
            information shown in <option>short</option> output mode this mode includes weekday, year and
            timezone information in the output, and is locale-independent.</para>

            <xi:include href="version-info.xml" xpointer="v232"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-iso</option></term>
            <listitem><para>is very similar, but shows timestamps in the
            <ulink url="https://tools.ietf.org/html/rfc3339">RFC 3339</ulink> profile of ISO 8601.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-iso-precise</option></term>
            <listitem><para>as for <option>short-iso</option> but includes full microsecond
            precision.</para>

            <xi:include href="version-info.xml" xpointer="v234"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-precise</option></term>
            <listitem><para>is very similar, but shows classic syslog timestamps with full microsecond
            precision.</para>

            <xi:include href="version-info.xml" xpointer="v207"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-monotonic</option></term>
            <listitem><para>is very similar, but shows monotonic timestamps instead of wallclock
            timestamps.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-delta</option></term>
            <listitem><para>as for <option>short-monotonic</option> but includes the time difference
            to the previous entry.
            Maybe unreliable time differences are marked by a <literal>*</literal>.</para>

            <xi:include href="version-info.xml" xpointer="v252"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>short-unix</option></term>
            <listitem><para>is very similar, but shows seconds passed since January 1st 1970 UTC instead of
            wallclock timestamps ("UNIX time"). The time is shown with microsecond accuracy.</para>

            <xi:include href="version-info.xml" xpointer="v230"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>verbose</option></term>
            <listitem><para>shows the full-structured entry items with all fields.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>export</option></term>
            <listitem><para>serializes the journal into a binary (but mostly text-based) stream suitable
            for backups and network transfer (see <ulink
            url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-export-format">Journal Export
            Format</ulink> for more information). To import the binary stream back into native journald
            format use
            <citerefentry><refentrytitle>systemd-journal-remote</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>json</option></term>
            <listitem><para>formats entries as JSON objects, separated by newline characters (see <ulink
            url="https://systemd.io/JOURNAL_EXPORT_FORMATS#journal-json-format">Journal JSON Format</ulink>
            for more information). Field values are generally encoded as JSON strings, with three exceptions:
            <orderedlist>
              <listitem><para>Fields larger than 4096 bytes are encoded as <constant>null</constant>
              values. (This may be turned off by passing <option>--all</option>, but be aware that this may
              allocate overly long JSON objects.)</para></listitem>

              <listitem><para>Journal entries permit non-unique fields within the same log entry. JSON does
              not allow non-unique fields within objects. Due to this, if a non-unique field is encountered a
              JSON array is used as field value, listing all field values as elements.</para></listitem>

              <listitem><para>Fields containing non-printable or non-UTF8 bytes are encoded as arrays
              containing the raw bytes individually formatted as unsigned numbers.</para></listitem>
            </orderedlist>

            Note that this encoding is reversible (with the exception of the size limit).</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>json-pretty</option></term>
            <listitem><para>formats entries as JSON data structures, but formats them in multiple lines in
            order to make them more readable by humans.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>json-sse</option></term>
            <listitem><para>formats entries as JSON data structures, but wraps them in a format suitable for
            <ulink
            url="https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events">Server-Sent
            Events</ulink>.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>json-seq</option></term>
            <listitem><para>formats entries as JSON data structures, but prefixes them with an ASCII Record
            Separator character (0x1E) and suffixes them with an ASCII Line Feed character (0x0A), in
            accordance with <ulink url="https://tools.ietf.org/html/rfc7464">JavaScript Object Notation
            (JSON) Text Sequences </ulink> (<literal>application/json-seq</literal>).</para>

            <xi:include href="version-info.xml" xpointer="v240"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>cat</option></term>
            <listitem><para>generates a very terse output, only showing the actual message of each journal
            entry with no metadata, not even a timestamp. If combined with the
            <option>--output-fields=</option> option will output the listed fields for each log record,
            instead of the message.</para>

            <xi:include href="version-info.xml" xpointer="v206"/></listitem>
          </varlistentry>

          <varlistentry>
            <term><option>with-unit</option></term>
            <listitem><para>similar to <option>short-full</option>, but prefixes the unit and user unit names
            instead of the traditional syslog identifier. Useful when using templated instances, as it will
            include the arguments in the unit names.</para>

            <xi:include href="version-info.xml" xpointer="v239"/></listitem>
          </varlistentry>
        </variablelist></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--truncate-newline</option></term>

        <listitem><para>Truncate each log message at the first newline character on output, so that only the
        first line of each message is displayed.</para>

        <xi:include href="version-info.xml" xpointer="v254"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--output-fields=</option></term>

        <listitem><para>A comma separated list of the fields which should be included in the output. This
        has an effect only for the output modes which would normally show all fields
        (<option>verbose</option>, <option>export</option>, <option>json</option>,
        <option>json-pretty</option>, <option>json-sse</option> and <option>json-seq</option>), as well as
        on <option>cat</option>. For the former, the <literal>__CURSOR</literal>,
        <literal>__REALTIME_TIMESTAMP</literal>, <literal>__MONOTONIC_TIMESTAMP</literal>, and
        <literal>_BOOT_ID</literal> fields are always printed.</para>

        <xi:include href="version-info.xml" xpointer="v236"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-n</option></term>
        <term><option>--lines=</option></term>

        <listitem><para>Show the most recent journal events and limit the number of events shown. The argument
        is a positive integer or <literal>all</literal> to disable the limit. Additionally, if the number is
        prefixed with <literal>+</literal>, the oldest journal events are used instead. The default value is
        10 if no argument is given.</para>

        <para>If <option>--follow</option> is used, this option is implied. When not prefixed with <literal>+</literal>
        and used with <option>--grep=</option>, <option>--reverse</option> is implied.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-r</option></term>
        <term><option>--reverse</option></term>

        <listitem><para>Reverse output so that the newest entries are displayed first.</para>

        <xi:include href="version-info.xml" xpointer="v198"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--show-cursor</option></term>

        <listitem><para>The cursor is shown after the last entry after two dashes:</para>
        <programlisting>-- cursor: s=0639…</programlisting>
        <para>The format of the cursor is private and subject to change.</para>

        <xi:include href="version-info.xml" xpointer="v209"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--utc</option></term>

        <listitem><para>Express time in Coordinated Universal Time (UTC).</para>

        <xi:include href="version-info.xml" xpointer="v217"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-x</option></term>
        <term><option>--catalog</option></term>

        <listitem><para>Augment log lines with explanation texts from the message catalog. This will add
        explanatory help texts to log messages in the output where this is available. These short help texts
        will explain the context of an error or log event, possible solutions, as well as pointers to support
        forums, developer documentation, and any other relevant manuals. Note that help texts are not
        available for all messages, but only for selected ones. For more information on the message catalog,
        please refer to the <ulink url="https://www.freedesktop.org/wiki/Software/systemd/catalog">Message
        Catalog Developer Documentation</ulink>.</para>

        <para>Note: when attaching <command>journalctl</command> output to bug reports, please do
        <emphasis>not</emphasis> use <option>-x</option>.</para>

        <xi:include href="version-info.xml" xpointer="v196"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-hostname</option></term>

        <listitem><para>Don't show the hostname field of log messages originating from the local host. This
        switch has an effect only on the <option>short</option> family of output modes (see above).</para>

        <para>Note: this option does not remove occurrences of the hostname from log entries themselves, so
        it does not prevent the hostname from being visible in the logs.</para>

        <xi:include href="version-info.xml" xpointer="v230"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-full</option></term>
        <term><option>--full</option></term>
        <term><option>-l</option></term>

        <listitem><para>Ellipsize fields when they do not fit in available columns.  The default is to show
        full fields, allowing them to wrap or be truncated by the pager, if one is used.</para>

        <para>The old options <option>-l</option>/<option>--full</option> are not useful anymore, except to
        undo <option>--no-full</option>.</para>

        <xi:include href="version-info.xml" xpointer="v196"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-a</option></term>
        <term><option>--all</option></term>

        <listitem><para>Show all fields in full, even if they include unprintable characters or are very
        long. By default, fields with unprintable characters are abbreviated as "blob data". (Note that the
        pager may escape unprintable characters again.)</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-f</option></term>
        <term><option>--follow</option></term>

        <listitem><para>Show only the most recent journal entries, and continuously print new entries as
        they are appended to the journal.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-tail</option></term>

        <listitem><para>Show all stored output lines, even in follow mode. Undoes the effect of
        <option>--lines=</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-q</option></term>
        <term><option>--quiet</option></term>

        <listitem><para>Suppresses all informational messages (i.e. "-- Journal begins at …", "-- Reboot
        --"), any warning messages regarding inaccessible system journals when run as a normal
        user.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Pager Control Options</title>

    <para>The following options control page support:</para>

    <variablelist>

      <xi:include href="standard-options.xml" xpointer="no-pager" />

      <varlistentry>
        <term><option>-e</option></term>
        <term><option>--pager-end</option></term>

        <listitem><para>Immediately jump to the end of the journal inside the implied pager tool. This
        implies <option>-n1000</option> to guarantee that the pager will not buffer logs of unbounded
        size. This may be overridden with an explicit <option>-n</option> with some other numeric value,
        while <option>-nall</option> will disable this cap.  Note that this option is only supported for
        the <citerefentry
        project='man-pages'><refentrytitle>less</refentrytitle><manvolnum>1</manvolnum></citerefentry>
        pager.</para>

        <xi:include href="version-info.xml" xpointer="v198"/></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Forward Secure Sealing (FSS) Options</title>

    <para>The following options may be used together with the <option>--setup-keys</option> command described
    below:</para>

    <variablelist>
      <varlistentry>
        <term><option>--interval=</option></term>

        <listitem><para>Specifies the change interval for the sealing key when generating an FSS key pair
        with <option>--setup-keys</option>. Shorter intervals increase CPU consumption but shorten the time
        range of undetectable journal alterations. Defaults to 15min.</para>

        <xi:include href="version-info.xml" xpointer="v189"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--verify-key=</option></term>

        <listitem><para>Specifies the FSS verification key to use for the <option>--verify</option>
        operation.</para>

        <xi:include href="version-info.xml" xpointer="v189"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--force</option></term>

        <listitem><para>When <option>--setup-keys</option> is passed and Forward Secure Sealing (FSS) has
        already been configured, recreate FSS keys.</para>

        <xi:include href="version-info.xml" xpointer="v206"/></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Commands</title>

    <para>The following commands are understood. If none is specified the default is to display journal records:</para>

    <variablelist>
      <varlistentry>
        <term><option>-N</option></term>
        <term><option>--fields</option></term>

        <listitem><para>Print all field names currently used in all entries of the journal.</para>

        <xi:include href="version-info.xml" xpointer="v229"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-F</option></term>
        <term><option>--field=</option></term>

        <listitem><para>Print all possible data values the specified field can take in all entries of the
        journal.</para>

        <xi:include href="version-info.xml" xpointer="v195"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--list-boots</option></term>

        <listitem><para>Show a tabular list of boot numbers (relative to the current boot), their IDs, and
        the timestamps of the first and last message pertaining to the boot.</para>

        <xi:include href="version-info.xml" xpointer="v209"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--disk-usage</option></term>

        <listitem><para>Shows the current disk usage of all journal files. This shows the sum of the disk
        usage of all archived and active journal files.</para>

        <xi:include href="version-info.xml" xpointer="v190"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--vacuum-size=</option></term>
        <term><option>--vacuum-time=</option></term>
        <term><option>--vacuum-files=</option></term>

        <listitem><para><option>--vacuum-size=</option> removes the oldest archived journal files until the
        disk space they use falls below the specified size. Accepts the usual <literal>K</literal>,
        <literal>M</literal>, <literal>G</literal> and <literal>T</literal> suffixes (to the base of
        1024).</para>

        <para><option>--vacuum-time=</option> removes archived journal files older than the specified
        timespan. Accepts the usual <literal>s</literal> (default), <literal>m</literal>,
        <literal>h</literal>, <literal>days</literal>, <literal>weeks</literal>, <literal>months</literal>,
        and <literal>years</literal> suffixes, see
        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
        details.</para>

        <para><option>--vacuum-files=</option> leaves only the specified number of separate journal
        files.</para>

        <para>Note that running <option>--vacuum-size=</option> has only an indirect effect on the output
        shown by <option>--disk-usage</option>, as the latter includes active journal files, while the
        vacuuming operation only operates on archived journal files. Similarly,
        <option>--vacuum-files=</option> might not actually reduce the number of journal files to below the
        specified number, as it will not remove active journal files.</para>

        <para><option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
        <option>--vacuum-files=</option> may be combined in a single invocation to enforce any combination of
        a size, a time and a number of files limit on the archived journal files. Specifying any of these
        three parameters as zero is equivalent to not enforcing the specific limit, and is thus
        redundant.</para>

        <para>These three switches may also be combined with <option>--rotate</option> into one command. If
        so, all active files are rotated first, and the requested vacuuming operation is executed right
        after. The rotation has the effect that all currently active files are archived (and potentially new,
        empty journal files opened as replacement), and hence the vacuuming operation has the greatest effect
        as it can take all log data written so far into account.</para>

        <xi:include href="version-info.xml" xpointer="v218"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--verify</option></term>

        <listitem><para>Check the journal file for internal consistency. If the file has been generated
        with FSS enabled and the FSS verification key has been specified with
        <option>--verify-key=</option>, authenticity of the journal file is verified.</para>

        <xi:include href="version-info.xml" xpointer="v189"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--sync</option></term>

        <listitem><para>Asks the journal daemon to write all yet unwritten journal data to the backing file
        system and synchronize all journals. This call does not return until the synchronization operation
        is complete. This command guarantees that any log messages written before its invocation are safely
        stored on disk at the time it returns.</para>

        <xi:include href="version-info.xml" xpointer="v228"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--relinquish-var</option></term>

        <listitem><para>Asks the journal daemon for the reverse operation to <option>--flush</option>: if
        requested the daemon will write further log data to <filename>/run/log/journal/</filename> and
        stops writing to <filename>/var/log/journal/</filename>. A subsequent call to
        <option>--flush</option> causes the log output to switch back to
        <filename>/var/log/journal/</filename>, see above.</para>

        <xi:include href="version-info.xml" xpointer="v243"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--smart-relinquish-var</option></term>

        <listitem><para>Similar to <option>--relinquish-var</option>, but executes no operation if the root
        file system and <filename>/var/log/journal/</filename> reside on the same mount point. This operation
        is used during system shutdown in order to make the journal daemon stop writing data to
        <filename>/var/log/journal/</filename> in case that directory is located on a mount point that needs
        to be unmounted.</para>

        <xi:include href="version-info.xml" xpointer="v243"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--flush</option></term>

        <listitem><para>Asks the journal daemon to flush any log data stored in
        <filename>/run/log/journal/</filename> into <filename>/var/log/journal/</filename>, if persistent
        storage is enabled. This call does not return until the operation is complete. Note that this call is
        idempotent: the data is only flushed from <filename>/run/log/journal/</filename> into
        <filename>/var/log/journal/</filename> once during system runtime (but see
        <option>--relinquish-var</option> below), and this command exits cleanly without executing any
        operation if this has already happened. This command effectively guarantees that all data is flushed
        to <filename>/var/log/journal/</filename> at the time it returns.</para>

        <xi:include href="version-info.xml" xpointer="v217"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--rotate</option></term>

        <listitem><para>Asks the journal daemon to rotate journal files. This call does not return until
        the rotation operation is complete. Journal file rotation has the effect that all currently active
        journal files are marked as archived and renamed, so that they are never written to in future. New
        (empty) journal files are then created in their place. This operation may be combined with
        <option>--vacuum-size=</option>, <option>--vacuum-time=</option> and
        <option>--vacuum-file=</option> into a single command, see above.</para>

        <xi:include href="version-info.xml" xpointer="v227"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--header</option></term>

        <listitem><para>Instead of showing journal contents, show internal header information of the
        journal fields accessed.</para>

        <para>This option is particularly useful when trying to identify out-of-order journal entries, as
        happens for example when the machine is booted with the wrong system time.</para>

        <xi:include href="version-info.xml" xpointer="v187"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--list-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>

        <listitem><para>List the contents of the message catalog as a table of message IDs, plus their
        short description strings.</para>

        <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
        shown.</para>

        <xi:include href="version-info.xml" xpointer="v196"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--dump-catalog <optional><replaceable>128-bit-ID…</replaceable></optional></option></term>

        <listitem><para>Show the contents of the message catalog, with entries separated by a line
        consisting of two dashes and the ID (the format is the same as <filename>.catalog</filename>
        files).</para>

        <para>If any <replaceable>128-bit-ID</replaceable>s are specified, only those entries are
        shown.</para>

        <xi:include href="version-info.xml" xpointer="v199"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--update-catalog</option></term>

        <listitem><para>Update the message catalog index. This command needs to be executed each time new
        catalog files are installed, removed, or updated to rebuild the binary catalog
        index.</para>

        <xi:include href="version-info.xml" xpointer="v196"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--setup-keys</option></term>

        <listitem><para>Instead of showing journal contents, generate a new key pair for Forward Secure
        Sealing (FSS). This will generate a sealing key and a verification key. The sealing key is stored in
        the journal data directory and shall remain on the host. The verification key should be stored
        externally. Refer to the <option>Seal=</option> option in
        <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
        information on Forward Secure Sealing and for a link to a refereed scholarly paper detailing the
        cryptographic theory it is based on.</para>

        <xi:include href="version-info.xml" xpointer="v189"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned; otherwise, a non-zero failure code is returned.</para>
  </refsect1>

  <xi:include href="common-variables.xml" />

  <refsect1>
    <title>Examples</title>

    <para>Without arguments, all collected logs are shown unfiltered:</para>

    <programlisting>journalctl</programlisting>

    <para>With one match specified, all entries with a field matching the expression are shown:</para>

    <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service
journalctl _SYSTEMD_CGROUP=/user.slice/user-42.slice/session-c1.scope</programlisting>

    <para>If two different fields are matched, only entries matching both expressions at the same time are
    shown:</para>

    <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>

    <para>If two matches refer to the same field, all entries matching either expression are shown:</para>

    <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>

    <para>If the separator <literal>+</literal> is used, two expressions may be combined in a logical OR. The
    following will show all messages from the Avahi service process with the PID 28097 plus all messages from
    the D-Bus service (from any of its processes):</para>

    <programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>

    <para>To show all fields emitted <emphasis>by</emphasis> a unit and <emphasis>about</emphasis> the unit,
    option <option>-u</option>/<option>--unit=</option> should be used. <command>journalctl -u
    <replaceable>name</replaceable></command> expands to a complex filter similar to

    <programlisting>_SYSTEMD_UNIT=<replaceable>name</replaceable>.service
  + UNIT=<replaceable>name</replaceable>.service _PID=1
  + OBJECT_SYSTEMD_UNIT=<replaceable>name</replaceable>.service _UID=0
  + COREDUMP_UNIT=<replaceable>name</replaceable>.service _UID=0 MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1</programlisting>

    (see
    <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    for an explanation of those patterns).</para>

    <para>Show all logs generated by the D-Bus executable:</para>

    <programlisting>journalctl /usr/bin/dbus-daemon</programlisting>

    <para>Show all kernel logs from previous boot:</para>

    <programlisting>journalctl -k -b -1</programlisting>

    <para>Show a live log display from a system service <filename>apache.service</filename>:</para>

    <programlisting>journalctl -f -u apache</programlisting>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-journal-remote.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>systemd-journal-upload.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>
</refentry>