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11a1589223
Files which are installed as-is (any .service and other unit files, .conf files, .policy files, etc), are left as is. My assumption is that SPDX identifiers are not yet that well known, so it's better to retain the extended header to avoid any doubt. I also kept any copyright lines. We can probably remove them, but it'd nice to obtain explicit acks from all involved authors before doing that.
224 lines
10 KiB
XML
224 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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SPDX-License-Identifier: LGPL-2.1+
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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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_directory_fd</refname>
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<refname>sd_journal_open_files</refname>
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<refname>sd_journal_open_files_fd</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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<refname>SD_JOURNAL_OS_ROOT</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_directory_fd</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>int <parameter>fd</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_files_fd</function></funcdef>
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<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
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<paramdef>int <parameter>fds[]</parameter></paramdef>
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<paramdef>unsigned <parameter>n_fds</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 to <function>sd_journal_open()</function> but
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takes an absolute directory path as argument. All journal files in this directory will be opened and interleaved
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automatically. This call also takes a flags argument. The flags parameters accepted by this call are
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<constant>SD_JOURNAL_OS_ROOT</constant>, <constant>SD_JOURNAL_SYSTEM</constant>, and
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<constant>SD_JOURNAL_CURRENT_USER</constant>. If <constant>SD_JOURNAL_OS_ROOT</constant> is specified, journal
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files are searched for below the usual <filename>/var/log/journal</filename> and
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<filename>/run/log/journal</filename> relative to the specified path, instead of directly beneath it.
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The other two flags limit which files are opened, the same as for <function>sd_journal_open()</function>.
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</para>
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<para><function>sd_journal_open_directory_fd()</function> is similar to
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<function>sd_journal_open_directory()</function>, but takes a file descriptor referencing a directory in the file
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system instead of an absolute file system path.</para>
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<para><function>sd_journal_open_files()</function> is similar to <function>sd_journal_open()</function> but takes a
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<constant>NULL</constant>-terminated list of file paths to open. All files will be opened and interleaved
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automatically. This call also takes a flags argument, but it must be passed as 0 as no flags are currently
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understood for this call. Please note that in 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 moment, and the opening of specific files is
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inherently racy.</para>
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<para><function>sd_journal_open_files_fd()</function> is similar to <function>sd_journal_open_files()</function>
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but takes an array of open file descriptors that must reference journal files, instead of an array of file system
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paths. Pass the array of file descriptors as second argument, and the number of array entries in the third. The
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flags parameter must be passed as 0.</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>All functions listed here are thread-agnostic and only a single thread may operate
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on a given <structname>sd_journal</structname> object.</para>
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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>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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