path: root/man/journalctl.xml

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<refentry id="journalctl">

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

        <refnamediv>
                <refname>journalctl</refname>
                <refpurpose>Query the systemd journal</refpurpose>
        </refnamediv>

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

        <refsect1>
                <title>Description</title>

                <para><command>journalctl</command> may be used to
                query the contents of the
                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                journal as written by
                <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>

                <para>If called without parameter it will show the full
                contents of the journal, 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, if the character
                "<literal>+</literal>" appears as separate word on the
                command line all matches before and after are combined
                in a disjunction (i.e. logical OR).</para>

                <para>As shortcuts for a few types of field/value
                matches file paths may be specified. If a file path
                refers to an executable file, this is equivalent to an
                <literal>_EXE=</literal> match for the canonicalized
                binary path. Similar, if a path refers to a device
                node, this is equivalent to a
                <literal>_KERNEL_DEVICE=</literal> match for the
                device.</para>

                <para>Output is interleaved from all accessible
                journal files, whether they are rotated or currently
                being written, and regardless whether they belong to the
                system itself or are accessible user journals.</para>

                <para>All users are granted access to their private
                per-user journals. However, by default only root and
                users who are members of the <literal>adm</literal>
                group get access to the system journal and the
                journals of other users.</para>
        </refsect1>

        <refsect1>
                <title>Options</title>

                <para>The following options are understood:</para>

                <variablelist>
                        <varlistentry>
                                <term><option>--help</option></term>
                                <term><option>-h</option></term>

                                <listitem><para>Prints a short help
                                text and exits.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--version</option></term>

                                <listitem><para>Prints a short version
                                string and exits.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Do not pipe output into a
                                pager.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Show all fields in
                                full, even if they include unprintable
                                characters or are very
                                long.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Controls the number of
                                journal lines to show, counting from
                                the most recent ones. The argument is
                                optional, and if specified is a
                                positive integer. If not specified and
                                in follow mode defaults to 10. If this
                                option is not passed and follow mode
                                is not enabled, how many lines are
                                shown is not
                                limited.</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>--output=</option></term>
                                <term><option>-o</option></term>

                                <listitem><para>Controls the
                                formatting of the journal entries that
                                are shown. Takes one of
                                <literal>short</literal>,
                                <literal>short-monotonic</literal>,
                                <literal>verbose</literal>,
                                <literal>export</literal>,
                                <literal>json</literal>,
                                <literal>json-pretty</literal>,
                                <literal>cat</literal>. <literal>short</literal>
                                is the default and generates an output
                                that is mostly identical to the
                                formatting of classic syslog log
                                files, showing one line per journal
                                entry. <literal>short-monotonic</literal>
                                is very similar but shows monotonic
                                timestamps instead of wallclock
                                timestamps. <literal>verbose</literal>
                                shows the full structured entry items
                                with all
                                fields. <literal>export</literal>
                                serializes the journal into a binary
                                (but mostly text-based) stream
                                suitable for backups and network
                                transfer (see <ulink
                                url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
                                Export Format</ulink> for more
                                information). <literal>json</literal>
                                formats entries as JSON data
                                structures, one per
                                line. <literal>json-pretty</literal>
                                also formats entries as JSON data
                                structures, but formats them in
                                multiple lines in order to make them
                                more readable for
                                humans. <literal>cat</literal>
                                generates a very terse output only
                                showing the actual message of each
                                journal entry with no meta data, not
                                even a timestamp.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Suppresses any warning
                                message regarding inaccessible system
                                journals when run as normal
                                user.</para></listitem>
                        </varlistentry>

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

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

                        <varlistentry>
                                <term><option>--this-boot</option></term>
                                <term><option>-b</option></term>

                                <listitem><para>Show data only from
                                current boot.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Jump to the location
                                in the journal specified by the passed
                                cursor.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Takes an absolute
                                directory path as argument. If
                                specified journalctl will operate on the
                                specified journal directory instead of
                                the default runtime and system journal
                                paths.</para></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><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.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--new-id128</option></term>

                                <listitem><para>Instead of showing
                                journal contents generate a new 128
                                bit ID suitable for identifying
                                messages. This is intended for usage
                                by developers who need a new
                                identifier for a new message they
                                introduce and want to make
                                recognizable. Will print the new ID in
                                three different formats which can be
                                copied into source code or
                                similar.</para></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></listitem>
                        </varlistentry>

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

                                <listitem><para>Shows the current disk
                                usage of all
                                journal files.</para></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.</para></listitem>
                        </varlistentry>

                        <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></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></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></listitem>
                        </varlistentry>

                </variablelist>
        </refsect1>

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

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

        <refsect1>
                <title>Environment</title>

                <variablelist>
                        <varlistentry>
                                <term><varname>$SYSTEMD_PAGER</varname></term>
                                <listitem><para>Pager to use when
                                <option>--no-pager</option> is not given;
                                overrides <varname>$PAGER</varname>.  Setting
                                this to an empty string or the value
                                <literal>cat</literal> is equivalent to passing
                                <option>--no-pager</option>.</para></listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

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

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

                <para>Show all logs of the kernel device node <filename>/dev/sda</filename>:</para>

                <programlisting>journalctl /dev/sda</programlisting>

        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>