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12b42c7667
This did not really work out as we had hoped. Trying to do this upstream introduced several problems that probably makes it better suited as a downstream patch after all. At any rate, it is not releaseable in the current state, so we at least need to revert this before the release. * by adjusting the path to binaries, but not do the same thing to the search path we end up with inconsistent man-pages. Adjusting the search path too would be quite messy, and it is not at all obvious that this is worth the effort, but at any rate it would have to be done before we could ship this. * this means that distributed man-pages does not make sense as they depend on config options, and for better or worse we are still distributing man pages, so that is something that definitely needs sorting out before we could ship with this patch. * we have long held that split-usr is only minimally supported in order to boot, and something we hope will eventually go away. So before we start adding even more magic/effort in order to make this work nicely, we should probably question if it makes sense at all.
240 lines
10 KiB
XML
240 lines
10 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="sd_journal_open">
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<refentryinfo>
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<title>sd_journal_open</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>sd_journal_open</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_journal_open</refname>
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<refname>sd_journal_open_directory</refname>
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<refname>sd_journal_open_files</refname>
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<refname>sd_journal_open_container</refname>
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<refname>sd_journal_close</refname>
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<refname>sd_journal</refname>
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<refname>SD_JOURNAL_LOCAL_ONLY</refname>
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<refname>SD_JOURNAL_RUNTIME_ONLY</refname>
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<refname>SD_JOURNAL_SYSTEM</refname>
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<refname>SD_JOURNAL_CURRENT_USER</refname>
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<refpurpose>Open the system journal for reading</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_journal_open</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>int <parameter>flags</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_open_directory</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>const char *<parameter>path</parameter></paramdef>
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<paramdef>int <parameter>flags</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_open_files</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>const char **<parameter>paths</parameter></paramdef>
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<paramdef>int <parameter>flags</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_open_container</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>const char *<parameter>machine</parameter></paramdef>
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<paramdef>int <parameter>flags</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>sd_journal_close</function></funcdef>
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<paramdef>sd_journal *<parameter>j</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_journal_open()</function> opens the log journal
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for reading. It will find all journal files automatically and
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interleave them automatically when reading. As first argument it
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takes a pointer to a <varname>sd_journal</varname> pointer, which
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on success will contain a journal context object. The second
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argument is a flags field, which may consist of the following
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flags ORed together: <constant>SD_JOURNAL_LOCAL_ONLY</constant>
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makes sure only journal files generated on the local machine will
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be opened. <constant>SD_JOURNAL_RUNTIME_ONLY</constant> makes sure
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only volatile journal files will be opened, excluding those which
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are stored on persistent storage.
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<constant>SD_JOURNAL_SYSTEM</constant> will cause journal files of
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system services and the kernel (in opposition to user session
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processes) to be opened.
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<constant>SD_JOURNAL_CURRENT_USER</constant> will cause journal
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files of the current user to be opened. If neither
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<constant>SD_JOURNAL_SYSTEM</constant> nor
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<constant>SD_JOURNAL_CURRENT_USER</constant> are specified, all
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journal file types will be opened.</para>
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<para><function>sd_journal_open_directory()</function> is similar
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to <function>sd_journal_open()</function> but takes an absolute
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directory path as argument. All journal files in this directory
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will be opened and interleaved automatically. This call also takes
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a flags argument, but it must be passed as 0 as no flags are
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currently understood for this call.</para>
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<para><function>sd_journal_open_files()</function> is similar to
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<function>sd_journal_open()</function> but takes a
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<constant>NULL</constant>-terminated list of file paths to open.
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All files will be opened and interleaved automatically. This call
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also takes a flags argument, but it must be passed as 0 as no
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flags are currently understood for this call. Please note that in
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the case of a live journal, this function is only useful for
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debugging, because individual journal files can be rotated at any
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moment, and the opening of specific files is inherently
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racy.</para>
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<para><function>sd_journal_open_container()</function> is similar
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to <function>sd_journal_open()</function> but opens the journal
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files of a running OS container. The specified machine name refers
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to a container that is registered with
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<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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<para><varname>sd_journal</varname> objects cannot be used in the
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child after a fork. Functions which take a journal object as an
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argument (<function>sd_journal_next()</function> and others) will
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return <constant>-ECHILD</constant> after a fork.
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</para>
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<para><function>sd_journal_close()</function> will close the
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journal context allocated with
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<function>sd_journal_open()</function> or
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<function>sd_journal_open_directory()</function> and free its
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resources.</para>
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<para>When opening the journal only journal files accessible to
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the calling user will be opened. If journal files are not
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accessible to the caller, this will be silently ignored.</para>
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<para>See
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for an example of how to iterate through the journal after opening
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it with <function>sd_journal_open()</function>.</para>
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<para>A journal context object returned by
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<function>sd_journal_open()</function> references a specific
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journal entry as <emphasis>current</emphasis> entry, similar to a
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file seek index in a classic file system file, but without
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absolute positions. It may be altered with
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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and related calls. The current entry position may be exported in
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<emphasis>cursor</emphasis> strings, as accessible via
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<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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Cursor strings may be used to globally identify a specific journal
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entry in a stable way and then later to seek to it (or if the
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specific entry is not available locally, to its closest entry in
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time)
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<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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<para>Notification of journal changes is available via
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<function>sd_journal_get_fd()</function> and related calls.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>The <function>sd_journal_open()</function>,
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<function>sd_journal_open_directory()</function>, and
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<function>sd_journal_open_files()</function> calls return 0 on
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success or a negative errno-style error code.
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<function>sd_journal_close()</function> returns nothing.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_journal_open()</function>,
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<function>sd_journal_open_directory()</function> and
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<function>sd_journal_close()</function> interfaces are available
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as a shared library, which can be compiled and linked to with the
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<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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</refsect1>
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<refsect1>
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<title>History</title>
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<para><function>sd_journal_open()</function>,
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<function>sd_journal_close()</function>,
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<constant>SD_JOURNAL_LOCAL_ONLY</constant>,
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<constant>SD_JOURNAL_RUNTIME_ONLY</constant>,
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<constant>SD_JOURNAL_SYSTEM_ONLY</constant> were added in
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systemd-38.</para>
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<para><function>sd_journal_open_directory()</function> was added
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in systemd-187.</para>
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<para><constant>SD_JOURNAL_SYSTEM</constant>,
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<constant>SD_JOURNAL_CURRENT_USER</constant>, and
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<function>sd_journal_open_files()</function> were added in
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systemd-205. <constant>SD_JOURNAL_SYSTEM_ONLY</constant> was
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deprecated.</para>
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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>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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