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https://github.com/systemd/systemd-stable.git
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dca6219e04
Previously, when the main data hash table grows too full the performance simply started to decrease drastically. Instead, now simply rotate to a new journal file as the hash table gets to full, so that we can start with a new fresh empty hash table.
339 lines
16 KiB
XML
339 lines
16 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="journalctl">
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<refentryinfo>
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<title>journalctl</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>journalctl</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>journalctl</refname>
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<refpurpose>Query the systemd journal</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>journalctl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">MATCHES</arg></command>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>journalctl</command> may be used to
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query the contents of the
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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journal as written by
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<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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<para>If called without parameter will show the full
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contents of the journal, starting with the oldest
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entry collected.</para>
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<para>If one or more match arguments are passed the
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output is filtered accordingly. A match is in the
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format <literal>FIELD=VALUE</literal>,
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e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>,
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referring to the components of a structured journal
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entry. See
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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for a list of well-known fields. If multiple matches
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are specified matching different fields the log
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entries are filtered by both, i.e. the resulting output
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will show only entries matching all the specified
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matches of this kind. If two matches apply to the same
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field, then they are automatically matched as
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alternatives, i.e. the resulting output will show
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entries matching any of the specified matches for the
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same field. Finally, if the character
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"<literal>+</literal>" appears as separate word on the
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command line all matches before and after are combined
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in a disjunction (i.e. logical OR).</para>
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<para>Output is interleaved from all accessible
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journal files, whether they are rotated or currently
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being written, and regardless whether they belong to the
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system itself or are accessible user journals.</para>
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<para>All users are granted access to their private
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per-user journals. However, by default only root and
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users who are members of the <literal>adm</literal>
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group get access to the system journal and the
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journals of other users.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The following options are understood:</para>
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<variablelist>
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<varlistentry>
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<term><option>--help</option></term>
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<term><option>-h</option></term>
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<listitem><para>Prints a short help
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text and exits.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--version</option></term>
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<listitem><para>Prints a short version
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string and exits.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--no-pager</option></term>
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<listitem><para>Do not pipe output into a
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pager.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--all</option></term>
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<term><option>-a</option></term>
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<listitem><para>Show all fields in
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full, even if they include unprintable
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characters or are very
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long.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--follow</option></term>
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<term><option>-f</option></term>
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<listitem><para>Show only most recent
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journal entries, and continuously print
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new entries as they are appended to
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the journal.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--lines=</option></term>
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<term><option>-n</option></term>
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<listitem><para>Controls the number of
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journal lines to show, counting from
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the most recent ones. Takes a positive
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integer argument. In follow mode
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defaults to 10, otherwise is unset
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thus not limiting how many lines are
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shown.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--no-tail</option></term>
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<listitem><para>Show all stored output
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lines, even in follow mode. Undoes the
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effect of
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<option>--lines=</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--output=</option></term>
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<term><option>-o</option></term>
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<listitem><para>Controls the
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formatting of the journal entries that are
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shown. Takes one of
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<literal>short</literal>,
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<literal>short-monotonic</literal>,
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<literal>verbose</literal>,
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<literal>export</literal>,
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<literal>json</literal>,
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<literal>cat</literal>. <literal>short</literal>
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is the default and generates an output
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that is mostly identical to the
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formatting of classic syslog log
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files, showing one line per journal
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entry. <literal>short-monotonic</literal>
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is very similar but shows monotonic
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timestamps instead of wallclock
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timestamps. <literal>verbose</literal>
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shows the full structured entry items
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with all
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fields. <literal>export</literal>
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serializes the journal into a binary
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(but mostly text-based) stream
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suitable for backups and network
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transfer. <literal>json</literal>
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formats entries as JSON data
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structures. <literal>cat</literal>
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generates a very terse output only
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showing the actual message of each
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journal entry with no meta data, not
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even a timestamp.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--quiet</option></term>
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<term><option>-q</option></term>
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<listitem><para>Suppresses any warning
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message regarding inaccessible system
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journals when run as normal
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user.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--local</option></term>
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<term><option>-l</option></term>
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<listitem><para>Show only locally
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generated messages.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--this-boot</option></term>
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<term><option>-b</option></term>
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<listitem><para>Show data only from
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current boot.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--directory=</option></term>
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<term><option>-D</option></term>
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<listitem><para>Takes an absolute
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directory path as argument. If
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specified will operate on the
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specified journal directory instead of
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the default runtime and system journal
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paths.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--new-id128</option></term>
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<listitem><para>Instead of showing
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journal contents generate a new 128
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bit ID suitable for identifying
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messages. This is intended for usage
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by developers who need a new
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identifier for a new message they
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introduce and want to make
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recognizable. Will print the new ID in
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three different formats which can be
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copied into source code or
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similar.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--header</option></term>
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<listitem><para>Instead of showing
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journal contents show internal header
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information of the journal fiels
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accessed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Exit status</title>
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<para>On success 0 is returned, a non-zero failure
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code otherwise.</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist>
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<varlistentry>
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<term><varname>$SYSTEMD_PAGER</varname></term>
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<listitem><para>Pager to use when
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<option>--no-pager</option> is not given;
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overrides <varname>$PAGER</varname>. Setting
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this to an empty string or the value
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<literal>cat</literal> is equivalent to passing
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<option>--no-pager</option>.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>Without arguments all collected logs are shown
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unfiltered:</para>
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<programlisting>journalctl</programlisting>
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<para>With one match specified all entries with a field matching the expression are shown:</para>
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<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service</programlisting>
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<para>If two different fields are matched only entries matching both expressions at the same time are shown:</para>
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<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097</programlisting>
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<para>If two matches refer to the same field all entries matching either expression are shown:</para>
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<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _SYSTEMD_UNIT=dbus.service</programlisting>
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<para>If the separator "<literal>+</literal>" is used
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two expression may be combined in a logical OR. The
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following will show all messages from the Avahi
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service process with the PID 28097 plus all messages
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from the D-Bus service (from any of its
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processes):</para>
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<programlisting>journalctl _SYSTEMD_UNIT=avahi-daemon.service _PID=28097 + _SYSTEMD_UNIT=dbus.service</programlisting>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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